string interview questions problem solving

51 string interview questions (coding problems with solutions)

String questions come up frequently in coding interviews and you'll need to understand them thoroughly if you want to land a software engineering job.

Here's a quick list of string interview questions to get started with:

Given a string, create a new string without vowels and print that string.
Given a string, create a new string with the same characters in a random order.
Given a string containing some words in (possibly nested) parentheses, calculate if all parentheses match.
Find the longest common prefix of two given strings.
Given two strings, find the shortest edit distance to transform the first into the second.

Below, we have a much more extensive list of questions, including links to high quality solutions for each question.

And if you need a refresher on string basics, we also have a tutorial and cheat sheet towards the end of this guide.

Now let's get to the questions!

Easy string interview questions
Medium string interview questions
Hard string interview questions
String basics
String cheat sheet
Mock interviews for software engineers

Click here to practice coding interviews with ex-FAANG interviewers

1. easy string interview questions.

You might be tempted to try to read all of the possible questions and memorize the solutions, but this is not feasible. Interviewers will always try to find new questions, or ones that are not available online. Instead, you should use these questions to practice the fundamental concepts of strings.

As you consider each question, try to replicate the conditions you’ll encounter in your interview. Begin by writing your own solution without external resources in a fixed amount of time.

If you get stuck, go ahead and look at the solutions, but then try the next one alone again. Don’t get stuck in a loop of reading as many solutions as possible! We’ve analyzed dozens of questions and selected ones that are commonly asked and have clear and high quality answers.

Here are some of the easiest questions you might get asked in a coding interview. These questions are often asked during the ‘phone screen’ stage, so you should be comfortable answering them without being able to write code or use a whiteboard.

1.1 Remove Vowels from a String

Text guide (GeeksforGeeks)
Video guide (Kevin Naughton Jr.)

1.2 Defanging an IP Address

Code example (LeetCode)

1.3 Jewels and Stones

Text guide (Memogrocery)

1.4 Shuffle String

Text guide (Medium/RKP)
Video guide (Knowledge Mavens)

1.5 Split a String in Balanced Strings

Text guide (GeeksForGeeks)

1.6 To Lower Case

Text guide (Dev.to/Seanpgallivan)
Video guide (Nick White)

1.7 Unique Morse Code Words

1.8 count substrings with only one distinct letter.

Text guide (HelloACM)
Video guide (GeeksForGeeks)

1.9 Robot Return to Origin

Text guide (LeetCode)

1.10 Fizz Buzz

Text guide (ITNext/Kevin)
Video guide (Tom Scott)

1.11 First Unique Character in a String

Text guide (AfterAcademy)

1.12 Reverse String

1.13 valid anagram.

Video guide (Terrible Whiteboard)

1.14 Valid Palindrome

Text guide (Medium/Urfan)

1.15 Implement Strstr()

Text guide (RedQuark)
Video guide (Amell Peralta)

1.16 Valid Parentheses

Video guide (Back to Back SWE)

1.17 Roman to Integer

Video guide (Thecodingworld)

1.18 Longest Common Prefix

1.19 excel sheet column number.

Video guide (Knowledge Center)

1.20 Palindrome Permutation

2. medium string interview questions.

Here are some moderate-level questions that are often asked in a video call or onsite interview. You should be prepared to write code or sketch out the solutions on a whiteboard if asked.

2.1 Longest Substring Without Repeating Characters

Text guide (Medium/Nerd For Tech)
Video guide (Michael Muinos)

2.2 Longest Palindromic Substring

Video guide (NeetCode)
Video guide (Errichto)

2.3 String to Integer (atoi)

Text guide (Medium/Hary)
Video guide (TECH DOSE)

2.4 Letter Combinations of a Phone Number

Text guide (Dev.to/Seanpgallivan)

2.5 Generate Parentheses

Text guide (RedQuark)

2.6 Count and Say

Text guide (GeeksforGeeks)

2.7 Group Anagrams

Text guide (Techie Delight)

2.8 Decode Ways

Text guide (Toronto CS)
Video guide (CS Dojo)

2.9 Palindrome Partitioning

2.10 word break.

Text guide (ProgrammerSought)
Video guide (Happygirlzt)

2.11 Fraction to Recurring Decimal

2.12 largest number.

Text guide (Easy Explanations)
Video guide (Jayati Tiwari)

2.13 Implement Trie (Prefix Tree)

Text guide (Medium/Saurav)

2.14 Basic Calculator II

Text guide (Medium/Calvin)

2.15 Longest Substring with At Least K Repeating Characters

2.16 palindrome partitioning.

Text guide (LeetCode)
Video guide (BacktoBackSWE)

2.17 Reorganize String

2.18 zigzag conversion.

Video guide (Google Engineer Explains)

2.19 Decode String

Text guide (Medium/Signal Cat)

2.20 Multiply Strings

Text guide (Medium/Nikhil Anand)

3. Hard string interview questions

Similar to the medium section, these more difficult questions may be asked in an onsite or video call interview. You will likely be given more time if you are expected to create a full solution.

3.1 Regular Expression Matching

Video guide (NeetCode)

3.2 Wildcard Matching

Text guide (Techie Delight)
Video guide (Tushar Roy)

3.3 Minimum Window Substring

Text guide (Medium/Algo Shaft)
Video guide (Back to Back SWE)

3.4 Word Ladder

Video guide (Nick White)

3.5 Word Break II

Text guide (Educative)
Video guide (Babybear4812)

3.6 Word Search II

Text guide (Medium/Hary)
Video guide (Timothy H Chang)

3.7 Serialize and Deserialize Binary Tree

Text guide (Dev.to/Akhilpolke)
Video guide (BacktoBack SWE)

3.8 Longest Valid Parentheses

Video guide (Algorithms Made Easy)

3.9 Edit Distance

3.10 alien dictionary (string/graph).

Text guide (Medium/Timothy)
Video guide (Happygirlzt)

3.11 Design Search Autocomplete System

Code example (Cheonhyangzhang)

4. String basics

In order to crack the questions above and others like them, you’ll need to have a strong understanding of strings and how they work. Let’s get into it.

4.1 What is a string?

A string is an ordered sequence, or string, of characters. It is usually considered a data type and is often included as part of language primitives. In most languages, strings are implemented using an array of bytes. The bytes are encoded using some character encoding. Earlier systems used ASCII encoding, with Unicode encoding used in later systems.

4.1.1 Types of strings (Java, Python, C++)

C++ provides a mutable string, meaning the string contents can be changed after creation.

Python and Java provide an immutable string type. Immutable strings require a new string to be created if any changes are made. This has performance implications for string concatenation when joining a number of strings, running in quadratic time.

Java provides a mutable StringBuilder class, which should be used for concatenating multiple strings. In Python, generally the `.join` method on strings should be used, which accepts an iterable of multiple strings. Using Java's StringBuilder or Python’s `.join` provides a linear time solution for multiple string concatenations.

Another class of strings are C-style strings, so named as they are used in the C language. These strings are simple arrays. A special terminating character is stored directly after the last character of the string. This terminating character marks the end of the string within the array, or buffer. C++ has support for C-style strings, but it is preferable to use C++ style strings in pure C++ code.

Java, Python and C++ strings are more complex data structures, with class or struct methods for manipulating and querying them.

4.1.2 How strings store data

There are generally two types of string implementations: null-terminated strings (C strings), and non-null-terminated strings. The principal difference between these types of strings is how the termination and tracking the length of the string is handled.

Null-terminated strings (C strings) are character arrays terminated with a null (NUL) character, typically a byte with all bits set to 0. The length of the string is calculated by counting the characters in the string up to the terminating character. Care must be taken in working with C-style strings, as writing and reading past the end of the string terminator can result in buffer overflow errors, causing unexpected behaviour and security issues by overwriting or reading unrelated memory contents.

Non-null-terminated strings, as used in C++, Java and Python implementations, have the underlying array and the length stored separately. In Java this is a class with private fields for the character array and length, which are not directly accessible from outside the class.

C++, Java and Python strings have useful class and instance methods to work with strings. Commonly used are:

Substring queries to return a new string from a subset of the original string
Replace methods to return a new string with a specific sequence of character substituted for another
String formatters to create strings from a template and data variables
Trimming methods to create new strings without leading or trailing whitespace
Upper and lower case conversion methods
Methods to check if a string contains a given substring

For more advanced pattern matching in strings, Regular Expressions, or regexes, are commonly used. Most modern string implementations have support for regex queries.

4.1.3 Deep dive into tries

A trie, or prefix tree, is a type of search tree, often used with strings. The strangely spelt name is from "reTrieval," but is mostly pronounced as "try." Tries are useful for answering questions like, "Given an input sequence 'cod,' what possible words could be formed?" This makes tries useful for auto-completing words in text input in a range of use cases, including search and texting .

A trie data structure is made of nodes indexed with a single character key. Each node has references to its child nodes. The number of child nodes is bounded by the number of unique characters in the alphabet space making up the stored words. Often this is described as 26 for the English language, but it can be larger when taking into consideration accented characters, or if there are numeric and special characters in the alphabet space. Each node also has a flag signaling the end of a word, represented by a blue node below:

Since each node only contains one character, the complete key to that node is distributed from its parents down to that node. Retrieval of a key is a depth-first search of the trie. A search for a key ends when the end of the word node is reached. Inserting a new key is done by following the trie through each character of the new key, and adding each character as a trie node where needed, and marking the node of the last character as the end of the word.

Inserting and searching is O(keySize) time. Space requirements are much larger than a simple string though, at O(AlphabetSpace*keySize*n), n being the total number of keys in the trie.

5. Strings cheat sheet

String definition: A string is a sequence of characters, often implemented as an array.

You can download this cheat sheet here.

5.1 Related algorithms and techniques

State Machines
String Builder
Two pointers
Backtracking
Levenshtein Distance
Boyer-Moore string search algorithm
Knuth-Morris-Pratt Algorithm
Rubin-Karp Algorithm
Bitap algorithm
BW Data transform

5.2 Cheat sheet explained

The cheat sheet above is a summary of information you might need to know for an interview, but it’s usually not enough to simply memorize it. Instead, aim to understand each result so that you can give the answer in context.

The cheat sheet is broken into time complexity (the processing time for the various string operations) and space complexity (the amount of memory required). While you might be asked about these directly in relation to string data structures, it’s more likely that you will need to know these in relation to specific string-related algorithms, such as substring searching, which is what the second section of the cheat sheet details.

For more information about time and space requirements of different algorithms, read our complete guide to big-O notation and complexity analysis .

5.2.1 Time complexity

Accessing a character at a particular index in a string is an O(1) operation, as strings are stored as arrays. Deleting characters from immutable strings means creating a new string and copying the remaining characters over, so this is an O(n) operation. For mutable strings, it means removing characters and shifting remaining characters, which is also O(n). Inserting into a string is a similar level of work as deleting, again O(n) time for both mutable and immutable strings.

Searching for a substring using built-in methods in most languages is generally O(n*m), depending on the algorithm used. We explain this more in the algorithm section.

Slicing, or splitting, a string refers to creating multiple substrings by splitting a string on a character or character sequence. This is often used in parsing CSV type files. It runs in O(n) time, as each character needs to be copied out into the new strings.

Joining, or concatenating, strings is a more complex operation. For immutable strings, concatenating multiple strings can result in O(n 2 ) time complexity for large numbers of strings. In such cases, StringBuilder, or Python's '.join()' method is recommended. For concating two mutable strings, it is O(n+m), where n and m represent the number of characters in either string. Mutable strings can concatenate faster, depending on the underlying implementation. For implementations where the array is doubled in size each time a resizing is needed, string concatenation is closer to regular array time complexity.

Comparing strings is also O(n) time, as generally each character needs to be checked.

For tries, there are two significant operations: Inserting a new key, and retrieving (searching for) a key. Both run in O(m) time, where m is the size of the key. This makes tries very scalable, as the time complexity is not dependent on the size of the trie itself.

5.2.2 String algorithm complexity

Radix sort is usually shown in the context of sorting numbers, but it can be used to sort strings, if the buckets are indexed by characters rather than numbers. Essentially the alphabet space of the strings becomes the base as used by the radix sort algorithm.

Many string algorithms center around searching for all occurrences of a substring within a string. This is a fundamental operation in text-centered applications, from HTTP processing to word processing. The naive implementation slides the search pattern by one character over the length of the string to check for the pattern starting at each index. This makes it an O(m*(n-m+1)) operation, as the pattern needs to be checked at each character in the string. The more sophisticated algorithms in the list attempt to reduce this complexity. These algorithms reduce the time by using strategies such as precomputing tables, creating rolling hashes, and using caching state from previous matching. They also use the fact that useful information for shortcutting the naive search approach is available in the search pattern itself, for example, whether or not the search pattern has repeating characters can allow some sliding indexes to be skipped. In all, these algorithms provide ways to reduce searching to O(n) time complexity.

6. Mock interviews for software engineers

Before you start practicing interviews, you’ll want to make sure you have a strong understanding of not only linked lists but also the rest of the relevant data structures. Check out our guides for questions, explanations and helpful cheat sheets.

Linked lists
Stacks and Queues
Coding interview examples (with solutions)

Once you’re confident on all of the data structure topics, you’ll want to start practicing answering coding questions in an interview situation. One way of doing this is by practicing out loud, which is a very underrated way of preparing. However, sooner or later you’re probably going to want some expert interventions and feedback to really improve your interview skills.

That’s why we recommend practicing with ex-interviewers from top tech companies. If you know a software engineer who has experience running interviews at a big tech company, then that's fantastic. But for most of us, it's tough to find the right connections to make this happen. And it might also be difficult to practice multiple hours with that person unless you know them really well.

Here's the good news. We've already made the connections for you. We’ve created a coaching service where you can practice system design interviews 1-on-1 with ex-interviewers from leading tech companies. Learn more and start scheduling sessions today.

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10 comments:

Hi guys, here the first question is "How to find the maximum occurring character in given String?" but the solution link is for "How to Count Occurrences of a Character in String" Both are different, Please confirm...

Yes, you are right but once you know how to count character then the other one becomes simple because you just need to return the character with maximum count

boolean b=true;

yes both are different example 1)How to find the maximum occurring character in given String?" Malyalaum - a-3 (a is the maximum occurring character in given string) 2) How to Count Occurrences of a Character in String Malyalaum m-2 a-3 y-1 u-1 thank you,

That's correct but once you know how to count character then the other one becomes simple because you just need to return the character with maximum count

public class OccObj { public static void main(String[] args){ Scanner input=new Scanner(System.in); String s= input.next(); NoOfOcuu(s); } public static void NoOfOcuu(String s){ int c=0,c2=0; ArrayListn=new ArrayList<>(); char c1='0'; for(int i=0;i=i)&&(c2==0)) { if (s.charAt(i) == s.charAt(j)) { c++; } } } if(c>1){ n.add(s.charAt(i)); } if(c>0) { System.out.println("the vale:" + s.charAt(i) + " - " + c); } } } }

public static void NoOfOcuu(String s){ int c=0,c2=0; ArrayListn=new ArrayList<>(); char c1='0'; for(int i=0;i=i)&&(c2==0)) { if (s.charAt(i) == s.charAt(j)) { c++; } } } if(c>1){ n.add(s.charAt(i)); } if(c>0) { System.out.println("the vale:" + s.charAt(i) + " - " + c); } } }

19)function isPalindrome(str) { let emptyArr = []; for (let i = 0; i < str.length; i++) { let x = str[i]; if (x == "(" || x == "[" || x == "{") { emptyArr.push(x); continue; } if (emptyArr.length == 0) return false; let y; switch (x) { case ")": y = emptyArr.pop(); if (y == "{" || y == "[") return false; break; case "}": y = emptyArr.pop(); if (y == "(" || y == "[") return false; break; case "]": y = emptyArr.pop(); if (y == "(" || y == "{") return false; break; } } return emptyArr.length == 0; } if (isPalindrome("{}")) console.log(true); else console.log(false);

val str = "aabbbbaa" var l = str.length var s = "" while (l>0){ s = s + str.get(l-1) l-- } if(s.equals(str)) { println("palindrome string : " + s) }else{ println("No palindrome string : " + s) }

Hi guys, here is the solution for question number 4 "How to remove characters from the first String which are present in the second String?" public static void main(String[] args) { String st1 = "india is great"; String st2 = "in"; List secondStringList = st2.chars().mapToObj(c -> (char) c).collect(Collectors.toList()); String outputString = st1.chars().mapToObj(c -> (char) c).filter(c -> !secondStringList.contains(c)).map(ch -> new String(String.valueOf(ch))) .collect(Collectors.joining("")); System.out.println("outputString : " + outputString); }

Feel free to comment, ask questions if you have any doubt.

1. Can you explain what String Manipulation is and why it’s important in software development?

String manipulation refers to the process of handling and modifying strings, a sequence of characters, in programming. It’s crucial in software development for several reasons.

Firstly, it aids in data cleaning by removing unnecessary spaces or converting case types, enhancing data consistency. Secondly, it enables parsing where strings are broken into smaller parts for easier analysis. This is vital when dealing with large volumes of text data. Thirdly, string manipulation allows for effective communication between different systems through formatting strings to meet specific system requirements.

Moreover, it facilitates user-friendly outputs. By manipulating strings, developers can format information in a way that’s easy for users to understand. Lastly, it supports pattern matching and searching within strings, which is essential in many applications like search engines.

2. Can you describe how to reverse a string using an iterative approach in Python?

In Python, reversing a string using an iterative approach involves creating a new empty string and then appending each character from the original string to it in reverse order. This can be achieved by initializing an empty string, then iterating over the length of the original string starting from the last index (which is -1 in Python) and moving towards the first index (0). For each iteration, we append the current character to our new string. Here’s a simple code example:

This function takes an input string, iterates over it in reverse order, and appends each character to reversed_str . The result is a reversed version of the original string.

3. How would you remove all white spaces from a string without using the replace() method?

To remove all white spaces from a string without using the replace() method, we can use the split() and join() methods. The split() method splits a string into an array of substrings based on a specified delimiter, in this case, a space character. This effectively removes all spaces from the string. However, it leaves us with an array of substrings rather than a single string. To convert this back into a single string, we use the join() method which concatenates all elements of an array into a single string.

Here is a JavaScript example:

In this code snippet, ‘str’ initially contains a string with spaces. We then call the split() method on ‘str’, passing in a space character as the argument. This splits ‘str’ into an array of words. We immediately call join() on this array, passing in an empty string as the argument. This joins all the words together into a single string with no spaces.

4. What algorithms would you use to check if a string is a palindrome?

To check if a string is a palindrome, two algorithms can be used: the Two-Pointer Technique and the Stack Method.

The Two-Pointer Technique involves initializing two pointers at both ends of the string. The characters at these pointer positions are compared. If they match, the pointers move towards each other until they meet in the middle or cross paths. If all character comparisons match, the string is a palindrome.

The Stack Method uses a stack data structure to store half the string’s characters. It then pops off each character from the stack and compares it with the remaining half of the string. A matching sequence indicates a palindrome.

5. How would you go about finding the duplicate characters in a string?

To find duplicate characters in a string, I would use a hash map data structure. The key-value pair of the hash map would be character-frequency pairs. First, iterate through each character in the string and add it to the hash map with its frequency count. If a character is already present in the hash map, increment its frequency by one. After iterating through all characters, traverse the hash map. Any character with a frequency greater than one is a duplicate.

6. Can you explain the concept of string immutability? What are its implications in programming?

String immutability refers to the property of strings that prevents their modification once created. In programming languages like Python and Java, strings are immutable objects. This means when you try to update the value of an immutable string, a new object is created instead of modifying the original one.

The implications of string immutability in programming are significant. It enhances performance by allowing strings to be reused without creating additional copies. This saves memory space and improves efficiency. However, it can also lead to increased processing time if large numbers of strings need to be concatenated or manipulated, as each operation results in a new string object.

Immutable strings also contribute to safer code. Since they cannot be changed after creation, they can be used as keys in dictionaries or elements in sets without fear of unexpected changes. Moreover, they help maintain thread safety in multi-threaded environments because they eliminate the risk of data corruption due to simultaneous modifications from different threads.

7. How would you implement a case-insensitive string comparison function?

To implement a case-insensitive string comparison function, we can use the built-in functions provided by most programming languages. For instance, in Python, we would convert both strings to lower or upper case using the .lower() or .upper() methods respectively before comparing them.

Here’s an example:

In this code snippet, str1 and str2 are the two input strings. The .lower() method is called on each string to convert all characters to lowercase. Then, the equality operator ( == ) compares these modified strings. If they match, the function returns True; otherwise, it returns False.

8. In JavaScript, how would you convert a string to a number and vice versa?

In JavaScript, to convert a string to a number, you can use the Number() function or the parseInt() and parseFloat() functions. The Number() function converts the entire string while parseInt() and parseFloat() stop at the first non-numeric character.

Example: let str = “123”; let num = Number(str); // 123

For converting a number to a string, we use the toString() method. This method returns a string representing the specified number object.

Example: let num = 123; let str = num.toString(); // “123”

9. How would you check if two strings are anagrams of each other in a highly efficient way?

An efficient way to check if two strings are anagrams is by using a frequency count method. This involves creating a character array of size 26 for each string, representing the English alphabet. Each index in the array corresponds to a letter and its value represents the frequency of that letter in the string.

Firstly, initialize both arrays with zeros. Then iterate through each character in the first string, incrementing the corresponding index in the first array. Repeat this process for the second string but decrement the corresponding index in the second array.

Finally, compare the two arrays. If they’re identical, the strings are anagrams. Otherwise, they’re not. The time complexity of this approach is O(n), where n is the length of the strings.

10. Can you describe how you would find all permutations of a string?

To find all permutations of a string, we can use recursion. We start by fixing the first character and recursively generating permutations for the remaining characters. Once this is done, we swap the first character with the next one and repeat the process until we’ve swapped with every character in the string. This will generate all possible permutations as each position in the string is occupied by every character exactly once.

For example, consider the string “ABC”. Initially, ‘A’ is fixed and permutations are generated for ‘BC’. Then ‘B’ is swapped with ‘A’, so now ‘B’ is fixed and permutations are generated for ‘AC’. Finally, ‘C’ is swapped with ‘A’, so ‘C’ is fixed and permutations are generated for ‘AB’.

This method ensures that all permutations are found without repetition. However, it’s important to note that this approach has a time complexity of O(n*n!) due to the n! permutations and n recursive calls for each permutation.

11. How would you reverse words in a given sentence without using any library method?

To reverse words in a sentence without using any library method, we can follow these steps:

1. Convert the sentence into an array of words by splitting it at spaces. 2. Initialize an empty string to hold the reversed sentence. 3. Iterate over the word array from end to start. 4. For each iteration, append the current word and a space to the reversed sentence. 5. After the loop ends, remove the trailing space from the reversed sentence.

Here is a Python code example:

12. What methods would you use to find the length of a string without using the len() function?

To find the length of a string without using len(), we can use two methods. The first method is to use a for loop. Initialize a counter variable at zero, then iterate over each character in the string, incrementing the counter by one each time. At the end of the loop, the counter will hold the length of the string.

The second method involves using the reduce function from the functools module. This function applies a binary function (a function that takes two arguments) to all items in an iterable in a cumulative way. We can pass a lambda function that increments a counter for each character in the string and the string itself as the iterable.

Here’s how it looks in code:

13. Can you demonstrate how to count the occurrence of a given character in a string?

Yes, I can demonstrate this using Python. The built-in count() function is used to count the occurrence of a character in a string.

In this code, we define a function called char_count that takes two parameters: a string and a character. Inside the function, we use the count() method on the string to count the number of times the character appears. We then call this function with a test string and character, and print the result.

14. How would you convert a string to a character array in Java?

In Java, a string can be converted to a character array using the built-in method “toCharArray()”. This method is part of the String class and returns an array containing each character in the original string. Here’s how it works:

In this code snippet, we first declare a string ‘str’ with the value “Example”. Then, we call the “toCharArray()” method on ‘str’, which converts it into a character array ‘charArray’. Now, ‘charArray’ contains the individual characters of “Example”.

15. Can you explain the differences between a string and a string buffer?

A string is an immutable object in Java, meaning once it’s created, its state cannot be changed. Any modification to a String results in a new instance, leading to memory inefficiency if many modifications are made.

On the other hand, StringBuffer is mutable. Modifications like append or insert can be made without creating a new instance. This makes StringBuffer more efficient when performing repeated operations on strings.

Another difference lies in synchronization. StringBuffer methods are synchronized, making them thread-safe and suitable for multi-threading environments. In contrast, String is not thread-safe.

16. How would you implement multi-line strings in Python and Java?

In Python, multi-line strings are implemented using triple quotes. You can use either three single quotes (”’) or three double quotes (“””). For example:

Java doesn’t directly support multi-line strings. However, you can achieve this by concatenating strings with the ‘+’ operator and including newline characters (‘\n’). Alternatively, since Java 13, you can use text blocks which are enclosed in triple double quotes (“””…”””). Here’s an example:

18. Can you explain how string concatenation works in JavaScript?

In JavaScript, string concatenation is the process of joining two or more strings together. This can be achieved using the ‘+’ operator or the ‘concat()’ method.

The ‘+’ operator merges two strings into one. For example, let’s consider two strings: var str1 = “Hello”; var str2 = “World”. The concatenated string would be: var result = str1 + ” ” + str2; //result is “Hello World”.

Alternatively, the ‘concat()’ method can also be used for string concatenation. It combines the text from two (or more) strings and returns a new string. Using our previous variables, we could write: var result = str1.concat(” “, str2); //result is “Hello World”.

It’s important to note that neither the ‘+’ operator nor the ‘concat()’ method modify the original strings. They both return a new string which is the result of the concatenation.

19. How would you find the longest palindrome in a given string?

To find the longest palindrome in a string, we can use dynamic programming. We initialize a 2D array of size n*n (where n is the length of the string) to false. Each cell [i][j] represents whether the substring from index i to j is a palindrome.

We then iterate over the string in reverse order. For each character, we check all substrings that end with this character. If the substring is a palindrome, we update our answer.

The pseudocode for this algorithm would be:

20. Can you write a function to check if a string is a substring of another string without using any built-in functions?

Yes, a function can be written to check if a string is a substring of another without using built-in functions. Here’s an example in Python:

This function iterates over the main string and checks each character against the corresponding character in the potential substring. If all characters match, it returns True; otherwise, it continues checking until it has exhausted all possibilities or found a match.

21. How would you count the number of vowels and consonants in a string?

To count the number of vowels and consonants in a string, we can use an iterative approach. First, initialize two counters to zero: one for vowels and another for consonants. Then, iterate over each character in the string. If the character is a vowel (a, e, i, o, u), increment the vowel counter. If it’s a letter but not a vowel, increment the consonant counter. Here’s a Python example:

This function converts the input string to lowercase, then iterates through each character. It checks whether the character is a letter and if so, whether it’s a vowel or a consonant, updating the respective counters accordingly.

22. Can you explain the role of escape sequences in string manipulation?

Escape sequences play a crucial role in string manipulation by allowing the inclusion of special characters within strings that cannot be typed directly. They are denoted by a backslash (\) followed by a letter or combination of digits. For instance, “\n” is used for a new line, “\t” for a tab, and “\\” to include a literal backslash. Escape sequences also enable the use of non-printable ASCII control characters like “\0″ (null character). In coding languages such as Python, escape sequences can be used with both single (‘ ‘) and double (” “) quotes to prevent them from being interpreted as the end of a string.

23. How would you find the first non-repeating character in a string?

To find the first non-repeating character in a string, we can use a hash map. The keys of this map are characters from the input string and values are their counts. We iterate through the string, for each character, if it’s not already in the map, add it with count 1; if it is, increment its count. After that, iterate again over the string, checking each character’s count in the map. The first character with a count of 1 is our answer.

Here’s an example in Python:

24. How do you split a string into a list of words in Python?

In Python, the split() method is used to divide a string into a list of words. This function splits the string at each instance of white space by default. Here’s an example:

This code will output: [‘Hello’, ‘World’]

If you want to split on something other than whitespace, you can pass that as an argument to the split() function. For example:

This code will output: [‘apple’, ‘banana’, ‘cherry’]

25. Can you describe the difference in memory allocation between a string and a string builder in .NET?

In .NET, strings are immutable objects. This means once a string is created, it cannot be changed. Any operation that appears to modify the string actually creates a new one in memory. This can lead to inefficient use of resources when performing multiple modifications on a string.

On the other hand, StringBuilder is mutable. It allows for efficient manipulation of large or complex strings as it doesn’t create a new object in memory with each modification. Instead, it modifies the existing object, reducing memory usage and improving performance.

Top 25 knitr (R package) Interview Questions and Answers

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String cheatsheet for coding interviews

Introduction .

A string is a sequence of characters. Many tips that apply to arrays also apply to strings. You're recommended to read the page on Arrays before reading this page.

Common data structures for looking up strings:

Trie/Prefix Tree
Suffix Tree

Common string algorithms:

Rabin Karp for efficient searching of substring using a rolling hash
KMP for efficient searching of substring

Time complexity

A strings is an array of characters, so the time complexities of basic string operations will closely resemble that of array operations.

Operations involving another string

Here we assume the other string is of length m.

Things to look out for during interviews

Ask about input character set and case sensitivity. Usually the characters are limited to lowercase Latin characters, for example a to z.

Corner cases

Empty string
String with 1 or 2 characters
String with repeated characters
Strings with only distinct characters

Techniques

Many string questions fall into one of these buckets.

Counting characters

Often you will need to count the frequency of characters in a string. The most common way of doing that is by using a hash table/map in your language of choice. If your language has a built-in Counter class like Python, ask if you can use that instead.

If you need to keep a counter of characters, a common mistake is to say that the space complexity required for the counter is O(n). The space required for a counter of a string of latin characters is O(1) not O(n). This is because the upper bound is the range of characters, which is usually a fixed constant of 26. The input set is just lowercase Latin characters.

String of unique characters

A neat trick to count the characters in a string of unique characters is to use a 26-bit bitmask to indicate which lower case latin characters are inside the string.

To determine if two strings have common characters, perform & on the two bitmasks. If the result is non-zero, ie. mask_a & mask_b > 0 , then the two strings have common characters.

An anagram is word switch or word play. It is the result of rearranging the letters of a word or phrase to produce a new word or phrase, while using all the original letters only once. In interviews, usually we are only bothered with words without spaces in them.

To determine if two strings are anagrams, there are a few approaches:

Sorting both strings should produce the same resulting string. This takes O(n.log(n)) time and O(log(n)) space.
If we map each character to a prime number and we multiply each mapped number together, anagrams should have the same multiple (prime factor decomposition). This takes O(n) time and O(1) space. Examples: Group Anagram
Frequency counting of characters will help to determine if two strings are anagrams. This also takes O(n) time and O(1) space.

Palindrome

A palindrome is a word, phrase, number, or other sequence of characters which reads the same backward as forward, such as madam or racecar .

Here are ways to determine if a string is a palindrome:

Reverse the string and it should be equal to itself.
Have two pointers at the start and end of the string. Move the pointers inward till they meet. At every point in time, the characters at both pointers should match.

The order of characters within the string matters, so hash tables are usually not helpful.

When a question is about counting the number of palindromes, a common trick is to have two pointers that move outward, away from the middle. Note that palindromes can be even or odd length. For each middle pivot position, you need to check it twice - once that includes the character and once without the character. This technique is used in Longest Palindromic Substring .

For substrings, you can terminate early once there is no match
For subsequences, use dynamic programming as there are overlapping subproblems. Check out this question

Essential questions

These are essential questions to practice if you're studying for this topic.

Valid Anagram
Valid Palindrome
Longest Substring Without Repeating Characters

Recommended courses

Algomonster .

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Grokking the Coding Interview: Patterns for Coding Questions

This course on by Design Gurus expands upon the questions on the recommended practice questions but approaches the practicing from a questions pattern perspective, which is an approach I also agree with for learning and have personally used to get better at coding interviews. The course allows you to practice selected questions in Java, Python, C++, JavaScript and also provides sample solutions in those languages along with step-by-step visualizations. Learn and understand patterns, not memorize answers! Get lifetime access now →

Master the Coding Interview: Data Structures + Algorithms

This Udemy bestseller is one of the highest-rated interview preparation course (4.6 stars, 21.5k ratings, 135k students) and packs 19 hours worth of contents into it. Like Tech Interview Handbook, it goes beyond coding interviews and covers resume, non-technical interviews, negotiations. It's an all-in-one package! Note that JavaScript is being used for the coding demos. Check it out →

Introduction
Time complexity
Things to look out for during interviews
Corner cases
Essential questions
Recommended practice questions
Recommended courses

DEV Community

Posted on Jun 1, 2019 • Updated on Jan 10, 2021

How to solve String based Coding Problems?

A good thing about the string data structure is that if you know the array data structure, you can easily solve string-based problems because strings are nothing but a character array .

So all the techniques you know by solving array-based coding questions can be used to solve string programming questions as well.

Here is my list of some of the frequently asked string coding questions from programming job interviews:

How do you reverse a given string in place? ( solution )
How do you print duplicate characters from a string? ( solution )
How do you check if two strings are anagrams of each other? ( solution )
How do you find all the permutations of a string? ( solution )
How can a given string be reversed using recursion? ( solution )
How do you check if a string contains only digits? ( solution )
How do you find duplicate characters in a given string? ( solution )
How do you count the number of vowels and consonants in a given string? ( solution )
How do you count the occurrence of a given character in a string? ( solution )
How do you print the first non-repeated character from a string? ( solution )
How do you convert a given String into int like the atoi() ? ( solution )
How do you reverse words in a given sentence without using any library method? ( solution )
How do you check if two strings are a rotation of each other? ( solution )
How do you check if a given string is a palindrome? ( solution )
How do you find the length of the longest substring without repeating characters? (solution)
Given string str, How do you find the longest palindromic substring in str? (solution)
How to convert a byte array to String? ( solution )
how to remove the duplicate character from String? ( solution )
How to find the maximum occurring character in a given String? ( solution )
How do you remove a given character from String? ( solution )

These questions help improve your knowledge of string as a data structure.

If you can solve all these String questions without any help then you are in good shape.

For more advanced questions, I suggest you solve problems given in the Algorithm Design Manual by Steven Skiena , a book with the toughest algorithm questions.

If you need to revise your Data Structure and Algorithms concepts then you can also see these resources:

1. Data Structures and Algorithms: Deep Dive Using Java for Java developers

2. Algorithms and Data Structures in Python for those who love Python

3. JavaScript Algorithms and Data Structures Masterclass by Colt Steele for JavaScript programmers

4. Mastering Data Structures & Algorithms using C and C++ for those who are good at C/C++

These are some of the best courses on data structures and algorithms and you can choose the one which is most suitable for you. Btw, I will receive payments if you buy these courses

Now You're Ready for the Coding Interview

These are some of the most common questions outside of data structure and algorithms that help you to do really well in your interview.

I have also shared a lot of these questions on my javarevisited and java67 , so if you are really interested, you can always go there and search for them.

These common String based questions are the ones you need to know to successfully interview with any company, big or small, for any level of programming job.

If you are looking for a programming or software development job in 2018, you can start your preparation with this list of coding questions but you need to prepare other topics as well.

This list of 50+ data structure and algorithms problems provides good topics to prepare and also helps assess your preparation to find out your areas of strength and weakness.

Good knowledge of data structure and algorithms is important for success in coding interviews and that's where you should focus most of your attention.

Further Learning 10 Algorithm Books Every Programmer Should Read Top 5 Data Structure and Algorithm Books for Java Developers From 0 to 1: Data Structures & Algorithms in Java Data Structure and Algorithms Analysis --- Job Interview 50+ Data Structure and Coding Problems for Programmers 10 Data Structure, Algorithms and SQL Courses to Crack Coding Interviews 20+ Array Coding Problems for Programmers 20+ Linked List Coding Problems for Programmers 25+ System Design Coding Problems for interviews

Closing Notes

Thanks, You made it to the end of the article ... Good luck with your programming interview! It's certainly not going to be easy, but you are one step closer after practicing these questions.

If you like this article, then please share it with your friends and colleagues, and don't forget to follow javinpaul on Twitter!

P.S. --- If you need some FREE resources for Programming Job Interviews, you can check out this list of free data structure and algorithm courses to start your preparation.

Top comments (18)

Templates let you quickly answer FAQs or store snippets for re-use.

Location Portland, OR
Work Senior Fullstack Developer at Oregon Public Broadcasting
Joined Jun 2, 2019

"Thank you for selecting me as a candidate to interview, if you honestly think I've worked my way up to being a senior developer without knowing how to actually perform the job, then this isn't an organization I want to work for. I'm sure we both have more important things to do with our time, so why don't we go ahead and end this now."

Joined Sep 16, 2018

Well @Bradley, I do understand that after a certain level of experience you may find it offending solving these questions but that's not the goal. If you are hands-on with coding, you can easily solve these problems but if you struggle with solving these, it means you are a bit rusty and not really doing coding everyday.

It doesn't matter to me how easy the questions are to answer. To me:

The question is trying to verify that I know how to do trivial and/or esoteric operations off the top of my head, which lets be honest, who has ever had to reverse the words of a sentence? Likewise, who hasn't had to strip bad characters out of a string?

The interviewers care about my rote memorization, which has nothing to do with being a good developer.

The company put someone in charge of interviewing that isn't a developer and they pulled questions off the internet thinking this is what makes a great developer.

The person in charge of hiring is too busy or too lazy to put the time into determining if a long list of candidates are a good fit for their organization, so they use this as a quick way to weed out candidates in round one. Mission successful; if they're not going to put the time into selecting quality candidates then right off the bat I'm not too excited about my prospective coworkers, nor the support I can expect from the organization.

What I'm saying is that a company asking this type of question tells me all I need to know about that company.

About the most I'll do is some sort of take home project and discuss at the interview: at least then I can either use a language or library I haven't used in a long time or learn a new one while I'm doing the project so that I'm not wasting my time.

Joined Jun 1, 2019

Exactly! Job interviews are a two-way thing. Or at least they should be.

Joined Aug 15, 2018

Horrible idea for a job interview. Perhaps for a junior position, or even for an internship, but not for a senior, or at least for minimally independent position. All of those problems are easily solvable with Google. On the other hand, as a senior, you have to work with multiple different languages, technologies, paradigms and be able to to figure out best way to solve the problem, having multiple proposed solutions. Problems you referred are trivial, well known and deeply exploited.

From my experience, I had people who excelled at this kind of questions but failed at "as a java developer i won't touch js/html" kind of test. As a scrum master and main developer on the team I cannot accept situation where one of the members can't (don't want to) handle tasks other people do.

As interviewer I like this question: which features of java8+ are most important to you? It gives the interviewee chance to gather thoughts, check if he is up to date and on which parts of the language he focuses. And there is no "bad" answer. All answers reflect how they think, what they focus on, and, honestly, if you rate people's creativity by number of algorithms they memorized, you'll assemble a team of losers who can't solve any problem unless it's already solved by a business analyst.

I don't want to work for you. Sorry.

Possibly the worst way to hire someone. They give zero indication of a devs ability.

I don't know why you think so because this is not the only interview anyone will give to get the job. It's not that easy. this is just a part of a big hiring process.

The java example of reversing a string in-place is wrong. Strings are immutable in Java. The example given will involve two array copies.

Well, while you are correct, it's about logic. In reality, it's better to use StringBuilder.reverse() but yes, mentioning that fact can impress some interviewers too.

I think that trying to let things clear during the interview helps the candidate to understand the importance behind these kind of questions. In one of the process I participated the interviewer explained that solving the string problems I was facing was not the point. He explained the time constraints the projects used to demand in the company and for that reason code performance and complexity concerns would be also evaluated. String problems themselves probably do not represent the scenario a candidate will be working on, but perhaps telling about the skills required to not hit the iceberg helps to care about its top.

For comparison, look here: businessinsider.com/how-tech-compa...

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String – Interview Questions and Practice Problems

A string is traditionally a sequence of characters, either as a literal constant or as some kind of variable. The latter may allow its elements to be mutated and the length changed, or it may be fixed (after creation).

A string is generally understood as a data type and is often implemented as an array of bytes (or words) that stores a sequence of elements, typically characters. String datatypes have historically allocated one byte per character. In C, the length of a string can be stored implicitly by using a special terminating character; often this is the null character (NUL), which has all bits zero.

Following is the list of commonly asked string interview questions:

Check if a string is a rotated palindrome or not Medium
Longest Palindromic Substring Problem Medium
Check if a repeated subsequence is present in a string or not Hard
Check if strings can be derived from each other by circularly rotating them Easy
Check if a set of moves is circular or not Medium
Convert a number into a corresponding excel column name Medium
Determine whether two strings are anagram or not Easy
Find all interleaving of given strings Easy
Isomorphic Strings Medium
Find all possible palindromic substrings of a string Hard
Find all possible combinations of words formed from the mobile keypad Hard
Find all possible combinations by replacing given digits with characters of the corresponding list Hard
>Find all words that follow the same order of characters as given pattern Medium
Group anagrams together from a list of words Medium
Find minimum operations required to transform a string into another string Hard
Determine whether a string can be transformed into another string in a single edit Medium
In-place remove all occurrences of AB and C from a string Easy
Find the longest even-length palindromic sum substring of a string Medium
Print string in the zigzag form in k rows Medium
Run Length Encoding (RLE) Data Compression Algorithm Easy
Find the longest substring of a string containing k distinct characters Hard
Find all palindromic permutations of a string Medium
Find all substrings of a string that are a permutation of another string Medium
Find the longest substring of a string containing distinct characters Medium
Find all permutations of a string – C++ , Java , Python Hard
Iterative approach to finding permutations of a string Hard
Find all lexicographically next permutations of a string sorted in ascending order Hard
Lexicographically Minimal String Rotation Medium
Find all strings of a given length containing balanced parentheses Medium
Find all combinations of non-overlapping substrings of a string Medium
Determine whether a string is a palindrome or not Easy
Find the minimum number of inversions needed to make an expression balanced Medium
Construct the longest palindrome by shuffling or deleting characters from a string Medium
Print all combinations of phrases formed by picking words from each of the given lists Medium
Break a string into all possible combinations of non-overlapping substrings Medium
Remove all extra spaces from a string Medium
Remove adjacent duplicate characters from a string Easy
Find the first non-repeating character in a string by doing only one traversal of it Medium
Find all n-digit strictly increasing numbers (Bottom-up and Top-down approach) Medium
Find all n-digit binary numbers having more 1’s than 0’s for any prefix Medium
Find all n-digit numbers with a given sum of digits Hard
Find all n-digit binary numbers with k-bits set where k ranges from 1 to n Hard
Find all n-digit binary numbers with an equal sum of bits in their two halves Hard
Find all n-digit numbers with equal sum of digits at even and odd indices Hard
Find all lexicographic permutations of a string Hard
Lexicographic rank of a string Hard
Find all lexicographically previous permutations of a string sorted in descending order Hard
Replace all non-overlapping occurrences of a pattern Medium
Find all substrings containing exactly k distinct characters Medium
Introduction to Pattern Matching Beginner
Implementation of KMP Algorithm Hard
Reverse a string using recursion Easy
Determine whether the characters of a string follow a specified order or not Medium
In-place remove all adjacent duplicates from a string Medium
Check if a sentence is syntactically correct or not Medium
Number to word conversion Hard
Implement strstr function in Java Easy
Shortest Superstring Problem Hard
Find the shortest route in a device to construct a given string Medium
Find the minimum number possible by doing at-most k swaps Medium
Determine whether a string matches with a given pattern Hard
Find all occurrences of the given string in a character matrix Hard
Difference between Subarray, Subsequence, and Subset Beginner
Check if an expression is balanced or not Easy
Find duplicate parenthesis in an expression Medium
Evaluate a postfix expression Easy
Decode a given sequence to construct a minimum number without repeated digits Hard
Convert an infix expression into a postfix expression Medium
Reverse a string using a stack data structure Easy
Find all binary strings that can be formed from a wildcard pattern Medium
Find the length of the longest balanced parenthesis in a string Hard
Reverse text without reversing individual words Medium
Reverse a string without using recursion Easy
Combinations of words formed by replacing given numbers with corresponding alphabets Hard
Longest Common Prefix (LCP) Problem Easy
Longest Common Subsequence Problem Medium
Longest Common Subsequence (LCS) | Space optimized version Medium
Longest Common Subsequence of k–sequences Medium
Longest Common Subsequence | Finding all LCS Hard
Longest Common Substring Problem Medium
Longest Palindromic Subsequence using Dynamic Programming Medium
Longest Repeated Subsequence Problem Medium
Implement Diff Utility Medium
Shortest Common Supersequence Problem Medium
Shortest Common Supersequence | Finding all SCS Hard
Shortest Common Supersequence Problem using LCS Hard
The Levenshtein distance (Edit distance) Problem Medium
Count the number of times a pattern appears in a given string as a subsequence Hard
Word Break Problem – Dynamic Programming Hard
Check if a string is k–palindrome or not Hard
Wildcard Pattern Matching Hard
Find the minimum number of deletions required to convert a string into a palindrome Medium
Find minimum cuts needed for the palindromic partition of a string Hard
Check if a string matches with the given wildcard pattern Hard
Check if a string is interleaving of two other given strings Medium
Find correct order of alphabets in a given dictionary of ancient origin Hard
Find first k non-repeating characters in a string in a single traversal Medium
Check if a linked list of strings is palindromic Easy
Generate binary numbers between 1 to n using a queue Easy
Longest Common Prefix in a given set of strings (using Trie) Medium
Lexicographic sorting of a given set of keys Medium
Find the maximum occurring word in a given set of strings Easy
Find first k maximum occurring words in a given set of strings Medium
Word Break Problem – Using Trie Data Structure Medium
Find all words matching a pattern in the given dictionary Medium
Find the shortest unique prefix for every word in an array Medium

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15 Common Problem-Solving Interview Questions

In an interview for a big tech company, I was asked if I’d ever resolved a fight — and the exact way I went about handling it. I felt blindsided, and I stammered my way through an excuse of an answer.

It’s a familiar scenario to fellow technical job seekers — and one that risks leaving a sour taste in our mouths. As candidate experience becomes an increasingly critical component of the hiring process, recruiters need to ensure the problem-solving interview questions they prepare don’t dissuade talent in the first place.

Interview questions designed to gauge a candidate’s problem-solving skills are more often than not challenging and vague. Assessing a multifaceted skill like problem solving is tricky — a good problem solver owns the full solution and result, researches well, solves creatively and takes action proactively.

It’s hard to establish an effective way to measure such a skill. But it’s not impossible.

We recommend taking an informed and prepared approach to testing candidates’ problem-solving skills . With that in mind, here’s a list of a few common problem-solving interview questions, the science behind them — and how you can go about administering your own problem-solving questions with the unique challenges of your organization in mind.

Key Takeaways for Effective Problem-Solving Interview Questions

Problem solving lies at the heart of programming.
Testing a candidate’s problem-solving skills goes beyond the IDE. Problem-solving interview questions should test both technical skills and soft skills.
STAR, SOAR and PREP are methods a candidate can use to answer some non-technical problem-solving interview questions.
Generic problem-solving interview questions go a long way in gauging a candidate’s fit. But you can go one step further by customizing them according to your company’s service, product, vision, and culture.

Technical Problem-Solving Interview Question Examples

Evaluating a candidates’ problem-solving skills while using coding challenges might seem intimidating. The secret is that coding challenges test many things at the same time — like the candidate’s knowledge of data structures and algorithms, clean code practices, and proficiency in specific programming languages, to name a few examples.

Problem solving itself might at first seem like it’s taking a back seat. But technical problem solving lies at the heart of programming, and most coding questions are designed to test a candidate’s problem-solving abilities.

Here are a few examples of technical problem-solving questions:

1. Mini-Max Sum

This well-known challenge, which asks the interviewee to find the maximum and minimum sum among an array of given numbers, is based on a basic but important programming concept called sorting, as well as integer overflow. It tests the candidate’s observational skills, and the answer should elicit a logical, ad-hoc solution.

2. Organizing Containers of Balls

This problem tests the candidate’s knowledge of a variety of programming concepts, like 2D arrays, sorting and iteration. Organizing colored balls in containers based on various conditions is a common question asked in competitive examinations and job interviews, because it’s an effective way to test multiple facets of a candidate’s problem-solving skills.

3. Build a Palindrome

This is a tough problem to crack, and the candidate’s knowledge of concepts like strings and dynamic programming plays a significant role in solving this challenge. This problem-solving example tests the candidate’s ability to think on their feet as well as their ability to write clean, optimized code.

4. Subarray Division

Based on a technique used for searching pairs in a sorted array ( called the “two pointers” technique ), this problem can be solved in just a few lines and judges the candidate’s ability to optimize (as well as basic mathematical skills).

5. The Grid Search

This is a problem of moderate difficulty and tests the candidate’s knowledge of strings and searching algorithms, the latter of which is regularly tested in developer interviews across all levels.

Common Non-Technical Problem-Solving Interview Questions

Testing a candidate’s problem-solving skills goes beyond the IDE . Everyday situations can help illustrate competency, so here are a few questions that focus on past experiences and hypothetical situations to help interviewers gauge problem-solving skills.

1. Given the problem of selecting a new tool to invest in, where and how would you begin this task?

Key Insight : This question offers insight into the candidate’s research skills. Ideally, they would begin by identifying the problem, interviewing stakeholders, gathering insights from the team, and researching what tools exist to best solve for the team’s challenges and goals.

2. Have you ever recognized a potential problem and addressed it before it occurred?

Key Insight: Prevention is often better than cure. The ability to recognize a problem before it occurs takes intuition and an understanding of business needs.

3. A teammate on a time-sensitive project confesses that he’s made a mistake, and it’s putting your team at risk of missing key deadlines. How would you respond?

Key Insight: Sometimes, all the preparation in the world still won’t stop a mishap. Thinking on your feet and managing stress are skills that this question attempts to unearth. Like any other skill, they can be cultivated through practice.

4. Tell me about a time you used a unique problem-solving approach.

Key Insight: Creativity can manifest in many ways, including original or novel ways to tackle a problem. Methods like the 10X approach and reverse brainstorming are a couple of unique approaches to problem solving.

5. Have you ever broken rules for the “greater good?” If yes, can you walk me through the situation?

Key Insight: “Ask for forgiveness, not for permission.” It’s unconventional, but in some situations, it may be the mindset needed to drive a solution to a problem.

6. Tell me about a weakness you overcame at work, and the approach you took.

Key Insight: According to Compass Partnership , “self-awareness allows us to understand how and why we respond in certain situations, giving us the opportunity to take charge of these responses.” It’s easy to get overwhelmed when faced with a problem. Candidates showing high levels of self-awareness are positioned to handle it well.

7. Have you ever owned up to a mistake at work? Can you tell me about it?

Key Insight: Everybody makes mistakes. But owning up to them can be tough, especially at a workplace. Not only does it take courage, but it also requires honesty and a willingness to improve, all signs of 1) a reliable employee and 2) an effective problem solver.

8. How would you approach working with an upset customer?

Key Insight: With the rise of empathy-driven development and more companies choosing to bridge the gap between users and engineers, today’s tech teams speak directly with customers more frequently than ever before. This question brings to light the candidate’s interpersonal skills in a client-facing environment.

9. Have you ever had to solve a problem on your own, but needed to ask for additional help? How did you go about it?

Key Insight: Knowing when you need assistance to complete a task or address a situation is an important quality to have while problem solving. This questions helps the interviewer get a sense of the candidate’s ability to navigate those waters.

10. Let’s say you disagree with your colleague on how to move forward with a project. How would you go about resolving the disagreement?

Key Insight: Conflict resolution is an extremely handy skill for any employee to have; an ideal answer to this question might contain a brief explanation of the conflict or situation, the role played by the candidate and the steps taken by them to arrive at a positive resolution or outcome.

Strategies for Answering Problem-Solving Questions

If you’re a job seeker, chances are you’ll encounter this style of question in your various interview experiences. While problem-solving interview questions may appear simple, they can be easy to fumble — leaving the interviewer without a clear solution or outcome.

It’s important to approach such questions in a structured manner. Here are a few tried-and-true methods to employ in your next problem-solving interview.

1. Shine in Interviews With the STAR Method

S ituation, T ask, A ction, and R esult is a great method that can be employed to answer a problem-solving or behavioral interview question. Here’s a breakdown of these steps:

Situation : A good way to address almost any interview question is to lay out and define the situation and circumstances.
Task : Define the problem or goal that needs to be addressed. Coding questions are often multifaceted, so this step is particularly important when answering technical problem-solving questions.
Action : How did you go about solving the problem? Try to be as specific as possible, and state your plan in steps if you can.
Result : Wrap it up by stating the outcome achieved.

2. Rise above difficult questions using the SOAR method

A very similar approach to the STAR method, SOAR stands for S ituation, O bstacle, A ction, and R esults .

Situation: Explain the state of affairs. It’s important to steer clear of stating any personal opinions in this step; focus on the facts.
Obstacle: State the challenge or problem you faced.
Action: Detail carefully how you went about overcoming this obstacle.
Result: What was the end result? Apart from overcoming the obstacle, did you achieve anything else? What did you learn in the process?

3. Do It the PREP Way

Traditionally used as a method to make effective presentations, the P oint, R eason, E xample, P oint method can also be used to answer problem-solving interview questions.

Point : State the solution in plain terms.
Reasons: Follow up the solution by detailing your case — and include any data or insights that support your solution.
Example: In addition to objective data and insights, drive your answer home by contextualizing the solution in a real-world example.
Point : Reiterate the solution to make it come full circle.

How to Customize Problem-Solving Interview Questions

Generic problem-solving interview questions go a long way in gauging a candidate’s skill level, but recruiters can go one step further by customizing these problem-solving questions according to their company’s service, product, vision, or culture.

Here are some tips to do so:

Break down the job’s responsibilities into smaller tasks. Job descriptions may contain ambiguous responsibilities like “manage team projects effectively.” To formulate an effective problem-solving question, envision what this task might look like in a real-world context and develop a question around it.
Tailor questions to the role at hand. Apart from making for an effective problem-solving question, it gives the candidate the impression you’re an informed technical recruiter. For example, an engineer will likely have attended many scrums. So, a good question to ask is: “Suppose you notice your scrums are turning unproductive. How would you go about addressing this?”
Consider the tools and technologies the candidate will use on the job. For example, if Jira is the primary project management tool, a good problem-solving interview question might be: “Can you tell me about a time you simplified a complex workflow — and the tools you used to do so?”
If you don’t know where to start, your company’s core values can often provide direction. If one of the core values is “ownership,” for example, consider asking a question like: “Can you walk us through a project you owned from start to finish?”
Sometimes, developing custom content can be difficult even with all these tips considered. Our platform has a vast selection of problem-solving examples that are designed to help recruiters ask the right questions to help nail their next technical interview.

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6 REST API Interview Questions Every Developer Should Know

By Mike Simpson

When candidates prepare for interviews, they usually focus on highlighting their leadership, communication, teamwork, and similar crucial soft skills . However, not everyone gets ready for problem-solving interview questions. And that can be a big mistake.

Problem-solving is relevant to nearly any job on the planet. Yes, it’s more prevalent in certain industries, but it’s helpful almost everywhere.

Regardless of the role you want to land, you may be asked to provide problem-solving examples or describe how you would deal with specific situations. That’s why being ready to showcase your problem-solving skills is so vital.

If you aren’t sure who to tackle problem-solving questions, don’t worry, we have your back. Come with us as we explore this exciting part of the interview process, as well as some problem-solving interview questions and example answers.

What Is Problem-Solving?

When you’re trying to land a position, there’s a good chance you’ll face some problem-solving interview questions. But what exactly is problem-solving? And why is it so important to hiring managers?

Well, the good folks at Merriam-Webster define problem-solving as “the process or act of finding a solution to a problem.” While that may seem like common sense, there’s a critical part to that definition that should catch your eye.

What part is that? The word “process.”

In the end, problem-solving is an activity. It’s your ability to take appropriate steps to find answers, determine how to proceed, or otherwise overcome the challenge.

Being great at it usually means having a range of helpful problem-solving skills and traits. Research, diligence, patience, attention-to-detail , collaboration… they can all play a role. So can analytical thinking , creativity, and open-mindedness.

But why do hiring managers worry about your problem-solving skills? Well, mainly, because every job comes with its fair share of problems.

While problem-solving is relevant to scientific, technical, legal, medical, and a whole slew of other careers. It helps you overcome challenges and deal with the unexpected. It plays a role in troubleshooting and innovation. That’s why it matters to hiring managers.

How to Answer Problem-Solving Interview Questions

Okay, before we get to our examples, let’s take a quick second to talk about strategy. Knowing how to answer problem-solving interview questions is crucial. Why? Because the hiring manager might ask you something that you don’t anticipate.

Problem-solving interview questions are all about seeing how you think. As a result, they can be a bit… unconventional.

These aren’t your run-of-the-mill job interview questions . Instead, they are tricky behavioral interview questions . After all, the goal is to find out how you approach problem-solving, so most are going to feature scenarios, brainteasers, or something similar.

So, having a great strategy means knowing how to deal with behavioral questions. Luckily, there are a couple of tools that can help.

First, when it comes to the classic approach to behavioral interview questions, look no further than the STAR Method . With the STAR method, you learn how to turn your answers into captivating stories. This makes your responses tons more engaging, ensuring you keep the hiring manager’s attention from beginning to end.

Now, should you stop with the STAR Method? Of course not. If you want to take your answers to the next level, spend some time with the Tailoring Method , too.

With the Tailoring Method, it’s all about relevance. So, if you get a chance to choose an example that demonstrates your problem-solving skills, this is really the way to go.

We also wanted to let you know that we created an amazing free cheat sheet that will give you word-for-word answers for some of the toughest interview questions you are going to face in your upcoming interview. After all, hiring managers will often ask you more generalized interview questions!

Click below to get your free PDF now:

Get Our Job Interview Questions & Answers Cheat Sheet!

FREE BONUS PDF CHEAT SHEET: Get our " Job Interview Questions & Answers PDF Cheat Sheet " that gives you " word-word sample answers to the most common job interview questions you'll face at your next interview .

CLICK HERE TO GET THE JOB INTERVIEW QUESTIONS CHEAT SHEET

1. Can you tell me about a time when you had to solve a challenging problem?

In the land of problem-solving questions, this one might be your best-case scenario. It lets you choose your own problem-solving examples to highlight, putting you in complete control.

When you choose an example, go with one that is relevant to what you’ll face in the role. The closer the match, the better the answer is in the eyes of the hiring manager.

EXAMPLE ANSWER:

“While working as a mobile telecom support specialist for a large organization, we had to transition our MDM service from one vendor to another within 45 days. This personally physically handling 500 devices within the agency. Devices had to be gathered from the headquarters and satellite offices, which were located all across the state, something that was challenging even without the tight deadline. I approached the situation by identifying the location assignment of all personnel within the organization, enabling me to estimate transit times for receiving the devices. Next, I timed out how many devices I could personally update in a day. Together, this allowed me to create a general timeline. After that, I coordinated with each location, both expressing the urgency of adhering to deadlines and scheduling bulk shipping options. While there were occasional bouts of resistance, I worked with location leaders to calm concerns and facilitate action. While performing all of the updates was daunting, my approach to organizing the event made it a success. Ultimately, the entire transition was finished five days before the deadline, exceeding the expectations of many.”

2. Describe a time where you made a mistake. What did you do to fix it?

While this might not look like it’s based on problem-solving on the surface, it actually is. When you make a mistake, it creates a challenge, one you have to work your way through. At a minimum, it’s an opportunity to highlight problem-solving skills, even if you don’t address the topic directly.

When you choose an example, you want to go with a situation where the end was positive. However, the issue still has to be significant, causing something negative to happen in the moment that you, ideally, overcame.

“When I first began in a supervisory role, I had trouble setting down my individual contributor hat. I tried to keep up with my past duties while also taking on the responsibilities of my new role. As a result, I began rushing and introduced an error into the code of the software my team was updating. The error led to a memory leak. We became aware of the issue when the performance was hindered, though we didn’t immediately know the cause. I dove back into the code, reviewing recent changes, and, ultimately, determined the issue was a mistake on my end. When I made that discovery, I took several steps. First, I let my team know that the error was mine and let them know its nature. Second, I worked with my team to correct the issue, resolving the memory leak. Finally, I took this as a lesson about delegation. I began assigning work to my team more effectively, a move that allowed me to excel as a manager and help them thrive as contributors. It was a crucial learning moment, one that I have valued every day since.”

3. If you identify a potential risk in a project, what steps do you take to prevent it?

Yes, this is also a problem-solving question. The difference is, with this one, it’s not about fixing an issue; it’s about stopping it from happening. Still, you use problem-solving skills along the way, so it falls in this question category.

If you can, use an example of a moment when you mitigated risk in the past. If you haven’t had that opportunity, approach it theoretically, discussing the steps you would take to prevent an issue from developing.

“If I identify a potential risk in a project, my first step is to assess the various factors that could lead to a poor outcome. Prevention requires analysis. Ensuring I fully understand what can trigger the undesired event creates the right foundation, allowing me to figure out how to reduce the likelihood of those events occurring. Once I have the right level of understanding, I come up with a mitigation plan. Exactly what this includes varies depending on the nature of the issue, though it usually involves various steps and checks designed to monitor the project as it progresses to spot paths that may make the problem more likely to happen. I find this approach effective as it combines knowledge and ongoing vigilance. That way, if the project begins to head into risky territory, I can correct its trajectory.”

17 More Problem-Solving-Based Interview Questions

In the world of problem-solving questions, some apply to a wide range of jobs, while others are more niche. For example, customer service reps and IT helpdesk professionals both encounter challenges, but not usually the same kind.

As a result, some of the questions in this list may be more relevant to certain careers than others. However, they all give you insights into what this kind of question looks like, making them worth reviewing.

Here are 17 more problem-solving interview questions you might face off against during your job search:

How would you describe your problem-solving skills?
Can you tell me about a time when you had to use creativity to deal with an obstacle?
Describe a time when you discovered an unmet customer need while assisting a customer and found a way to meet it.
If you were faced with an upset customer, how would you diffuse the situation?
Tell me about a time when you had to troubleshoot a complex issue.
Imagine you were overseeing a project and needed a particular item. You have two choices of vendors: one that can deliver on time but would be over budget, and one that’s under budget but would deliver one week later than you need it. How do you figure out which approach to use?
Your manager wants to upgrade a tool you regularly use for your job and wants your recommendation. How do you formulate one?
A supplier has said that an item you need for a project isn’t going to be delivered as scheduled, something that would cause your project to fall behind schedule. What do you do to try and keep the timeline on target?
Can you share an example of a moment where you encountered a unique problem you and your colleagues had never seen before? How did you figure out what to do?
Imagine you were scheduled to give a presentation with a colleague, and your colleague called in sick right before it was set to begin. What would you do?
If you are given two urgent tasks from different members of the leadership team, both with the same tight deadline, how do you choose which to tackle first?
Tell me about a time you and a colleague didn’t see eye-to-eye. How did you decide what to do?
Describe your troubleshooting process.
Tell me about a time where there was a problem that you weren’t able to solve. What happened?
In your opening, what skills or traits make a person an exceptional problem-solver?
When you face a problem that requires action, do you usually jump in or take a moment to carefully assess the situation?
When you encounter a new problem you’ve never seen before, what is the first step that you take?

Putting It All Together

At this point, you should have a solid idea of how to approach problem-solving interview questions. Use the tips above to your advantage. That way, you can thrive during your next interview.

FREE : Job Interview Questions & Answers PDF Cheat Sheet!

Download our " Job Interview Questions & Answers PDF Cheat Sheet " that gives you word-for-word sample answers to some of the most common interview questions including:

What Is Your Greatest Weakness?
What Is Your Greatest Strength?
Tell Me About Yourself
Why Should We Hire You?

Click Here To Get The Job Interview Questions & Answers Cheat Sheet

Co-Founder and CEO of TheInterviewGuys.com. Mike is a job interview and career expert and the head writer at TheInterviewGuys.com.

His advice and insights have been shared and featured by publications such as Forbes , Entrepreneur , CNBC and more as well as educational institutions such as the University of Michigan , Penn State , Northeastern and others.

Learn more about The Interview Guys on our About Us page .

About The Author

Mike simpson.

Co-Founder and CEO of TheInterviewGuys.com. Mike is a job interview and career expert and the head writer at TheInterviewGuys.com. His advice and insights have been shared and featured by publications such as Forbes , Entrepreneur , CNBC and more as well as educational institutions such as the University of Michigan , Penn State , Northeastern and others. Learn more about The Interview Guys on our About Us page .

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25+ JavaScript Coding Interview Questions (SOLVED with CODE)

Having a JavaScript Coding Interview Session on this week? Fear not, we got your covered! Check that ultimate list of 25 advanced and tricky JavaScript Coding Interview Questions and Challenges to crack on your next senior web developer interview and got your next six-figure job offer in no time!

Q1 : Explain what a callback function is and provide a simple example

A callback function is a function that is passed to another function as an argument and is executed after some operation has been completed. Below is an example of a simple callback function that logs to the console after some operations have been completed.

Q2 : Given a string, reverse each word in the sentence

For example Welcome to this Javascript Guide! should be become emocleW ot siht tpircsavaJ !ediuG

Q3 : How to check if an object is an array or not? Provide some code.

The best way to find whether an object is instance of a particular class or not using toString method from Object.prototype

One of the best use cases of type checking of an object is when we do method overloading in JavaScript. For understanding this let say we have a method called greet which take one single string and also a list of string, so making our greet method workable in both situation we need to know what kind of parameter is being passed, is it single value or list of value?

However, in above implementation it might not necessary to check type for array, we can check for single value string and put array logic code in else block, let see below code for the same.

Now it's fine we can go with above two implementations, but when we have a situation like a parameter can be single value , array , and object type then we will be in trouble.

Coming back to checking type of object, As we mentioned that we can use Object.prototype.toString

If you are using jQuery then you can also used jQuery isArray method:

FYI jQuery uses Object.prototype.toString.call internally to check whether an object is an array or not.

In modern browser, you can also use:

Array.isArray is supported by Chrome 5, Firefox 4.0, IE 9, Opera 10.5 and Safari 5

Q4 : How to empty an array in JavaScript?

How could we empty the array above?

Above code will set the variable arrayList to a new empty array. This is recommended if you don't have references to the original array arrayList anywhere else because It will actually create a new empty array. You should be careful with this way of empty the array, because if you have referenced this array from another variable, then the original reference array will remain unchanged, Only use this way if you have only referenced the array by its original variable arrayList .

For Instance:

Above code will clear the existing array by setting its length to 0. This way of empty the array also update all the reference variable which pointing to the original array. This way of empty the array is useful when you want to update all the another reference variable which pointing to arrayList .

Above implementation will also work perfectly. This way of empty the array will also update all the references of the original array.

Above implementation can also empty the array. But not recommended to use often.

Q5 : How would you check if a number is an integer?

A very simply way to check if a number is a decimal or integer is to see if there is a remainder left when you divide by 1.

Q6 : Implement enqueue and dequeue using only two stacks

Enqueue means to add an element, dequeue to remove an element.

Q7 : Make this work

Q8 : write a "mul" function which will properly when invoked as below syntax.

Here mul function accept the first argument and return anonymous function which take the second parameter and return anonymous function which take the third parameter and return multiplication of arguments which is being passed in successive

In JavaScript function defined inside has access to outer function variable and function is the first class object so it can be returned by function as well and passed as argument in another function.

A function is an instance of the Object type
A function can have properties and has a link back to its constructor method
Function can be stored as variable
Function can be pass as a parameter to another function
Function can be returned from function

Q9 : Write a function that would allow you to do this?

You can create a closure to keep the value passed to the function createBase even after the inner function is returned. The inner function that is being returned is created within an outer function, making it a closure, and it has access to the variables within the outer function, in this case the variable baseNumber .

Q10 : FizzBuzz Challenge

Create a for loop that iterates up to 100 while outputting "fizz" at multiples of 3 , "buzz" at multiples of 5 and "fizzbuzz" at multiples of 3 and 5 .

Check out this version of FizzBuzz:

Q11 : Given two strings, return true if they are anagrams of one another

For example: Mary is an anagram of Army

Q12 : How would you use a closure to create a private counter?

You can create a function within an outer function (a closure) that allows you to update a private variable but the variable wouldn't be accessible from outside the function without the use of a helper function.

Q13 : Provide some examples of non-bulean value coercion to a boolean one

The question is when a non-boolean value is coerced to a boolean, does it become true or false , respectively?

The specific list of "falsy" values in JavaScript is as follows:

"" (empty string)
0 , -0 , NaN (invalid number)
null , undefined

Any value that's not on this "falsy" list is "truthy." Here are some examples of those:

[ ] , [ 1, "2", 3 ] (arrays)
{ } , { a: 42 } (objects)
function foo() { .. } (functions)

Q14 : What will be the output of the following code?

Above code would give output 1undefined . If condition statement evaluate using eval so eval(function f() {}) which return function f() {} which is true so inside if statement code execute. typeof f return undefined because if statement code execute at run time, so statement inside if condition evaluated at run time.

Above code will also output 1undefined .

Q15 : What will the following code output?

The code above will output 5 even though it seems as if the variable was declared within a function and can't be accessed outside of it. This is because

is interpreted the following way:

But b is not declared anywhere in the function with var so it is set equal to 5 in the global scope .

Q16 : Write a function that would allow you to do this

You can create a closure to keep the value of a even after the inner function is returned. The inner function that is being returned is created within an outer function, making it a closure, and it has access to the variables within the outer function, in this case the variable a .

Q17 : How does the this keyword work? Provide some code examples

In JavaScript this always refers to the “owner” of the function we're executing, or rather, to the object that a function is a method of.

Q18 : How would you create a private variable in JavaScript?

To create a private variable in JavaScript that cannot be changed you need to create it as a local variable within a function. Even if the function is executed the variable cannot be accessed outside of the function. For example:

To access the variable, a helper function would need to be created that returns the private variable.

Q19 : What is Closure in JavaScript? Provide an example

A closure is a function defined inside another function (called parent function) and has access to the variable which is declared and defined in parent function scope.

The closure has access to variable in three scopes:

Variable declared in his own scope
Variable declared in parent function scope
Variable declared in global namespace

innerFunction is closure which is defined inside outerFunction and has access to all variable which is declared and defined in outerFunction scope. In addition to this function defined inside function as closure has access to variable which is declared in global namespace .

Output of above code would be:

Q20 : What will be the output of the following code?

Above code will output 0 as output. delete operator is used to delete a property from an object. Here x is not an object it's local variable . delete operator doesn't affect local variable.

Q21 : What will be the output of the following code?

Above code will output xyz as output. Here emp1 object got company as prototype property. delete operator doesn't delete prototype property.

emp1 object doesn't have company as its own property. You can test it like:

However, we can delete company property directly from Employee object using delete Employee.company or we can also delete from emp1 object using __proto__ property delete emp1.__proto__.company .

Q22 : What will the following code output?

This will surprisingly output false because of floating point errors in internally representing certain numbers. 0.1 + 0.2 does not nicely come out to 0.3 but instead the result is actually 0.30000000000000004 because the computer cannot internally represent the correct number. One solution to get around this problem is to round the results when doing arithmetic with decimal numbers.

Q23 : When would you use the bind function?

The bind() method creates a new function that, when called, has its this keyword set to the provided value, with a given sequence of arguments preceding any provided when the new function is called.

A good use of the bind function is when you have a particular function that you want to call with a specific this value. You can then use bind to pass a specific object to a function that uses a this reference.

Q24 : Write a recursive function that performs a binary search

Q25 : describe the revealing module pattern design pattern.

A variation of the module pattern is called the Revealing Module Pattern . The purpose is to maintain encapsulation and reveal certain variables and methods returned in an object literal. The direct implementation looks like this:

An obvious disadvantage of it is unable to reference the private methods

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Clean Architecture provides a clear and modular structure for building software systems, separating business rules from implementation details. It promotes maintainability by allowing for easier updates and changes to specific components without affe...

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FullStack.Cafe is a biggest hand-picked collection of top Full-Stack, Coding, Data Structures & System Design Interview Questions to land 6-figure job offer in no time.

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Top 25+ JavaScript Interview Questions and Answers

Research shows that JavaScript is used in 12% of all technical interviews. However, only 42% of candidates pass these interviews. That’s why it is important to prepare in advance. And this is where our guide can help you. We’ve put together a comprehensive list of the top 25+ JavaScript interview questions with clear and straightforward answers.

Whether you’re an experienced developer or a fresher ready for your first interview, these questions cover basic and advanced JavaScript topics.

So, let’s get started!

Table of Contents

About JavaScript

JavaScript is a programming language used in web development to make websites interactive.

It adds behaviour to websites, letting them respond to user actions like form validation, animation, and data fetching without reloading the page.

JavaScript works on both front-end and back-end development , making it versatile for creating responsive and engaging web applications.

According to Statista, JavaScript is the top choice for web development, with about 63.61% of developers worldwide preferring it.

JavaScript is also in high demand in India’s tech industry due to its crucial role in web development and the rise of digital initiatives.

To find the perfect JavaScript job , use Hirist, India’s top IT job portal. Here, you can search for JavaScript jobs, choose your preferred location and experience level, and easily apply for jobs that fit your skills.

JavaScript Interview Questions for Freshers

Here are some commonly asked basic interview questions on JavaScript , along with their answers.

What is JavaScript?

JavaScript is a programming language used to create interactive elements on websites. It runs in web browsers and can manipulate webpage content, respond to user actions, and interact with servers.

What are variables in JavaScript?

Variables are used to store data values in JavaScript. They can hold different types of data like numbers, strings (text), and boolean (true/false) values.

What are the different data types in JavaScript?

JavaScript has several data types, including,

Number: Represents both integer and decimal (floating-point) numbers.
String: Represents sequences of characters or alphanumeric values.
Boolean: Represents true or false values.
Object: Represents collections of properties and complex values.
Null: Represents values that are intentionally empty or unknown.
Undefined: Indicates variables that have been declared but not assigned a value.
Symbols: Provides unique identifiers for objects and supports special use cases.
How do you declare a variable in JavaScript?

You can declare a variable using the var, let, or const keywords followed by the variable name.

For example:

var myNumber = 10;

let myName = “Rahul”;

const PI = 3.14;

What is an event in JavaScript?

An event is an action that occurs on a webpage, such as clicking a button or submitting a form. JavaScript can respond to these events by executing specific functions.

How do you create a function in JavaScript?

You can create a function using the function keyword followed by the function name and parameters.

function greet(name) {

return “Hello, ” + name + “!”;

How do you add an event listener in JavaScript?

You can add an event listener to an HTML element using the addEventListener method.

document.getElementById(“myButton”).addEventListener(“click”, function() {

alert(“Button clicked!”);

JavaScript Interview Questions Experienced

We have categorized the commonly asked JS programming interview questions and answers based on candidates’ experience levels.

JavaScript Interview Questions for 2 Year Experience

Here are some common JS interview questions and answers for candidates with 2 years of experience.

What are closures in JavaScript?

A closure is a feature in JavaScript that allows a function to remember and access its lexical scope even when it’s executed outside that scope. It helps in maintaining private variables and creating modular code.

Explain the difference between let, const, and var.

var is used to declare variables with function scope, while let and const have block scope (limited to the nearest curly braces). Variables declared with const cannot be changed after assignment, but variables declared with let can.

What is the difference between synchronous and asynchronous code in JavaScript?

Synchronous code runs line by line and blocks further execution until each line finishes. Asynchronous code allows tasks to run in the background and doesn’t wait for them to complete before moving on.

How does prototypal inheritance work in JavaScript?

JavaScript uses prototypal inheritance, where objects can inherit properties and methods from other objects. Each object has a prototype object from which it inherits properties.

Explain the concept of event bubbling and event delegation.

Event bubbling refers to the propagation of an event from the innermost element to the outermost element in the DOM hierarchy. Event delegation is a technique where a parent element handles events triggered by its child elements.

JavaScript Interview Questions for 3 Year Experience

Here are some important JS interview questions for candidates with 3 years of experience.

What are Promises in JavaScript?

Promises are used for asynchronous programming in JavaScript. They represent the eventual completion or failure of an asynchronous operation, allowing you to handle the result or error once it’s available.

Explain the concept of higher-order functions.

Higher-order functions are functions that can take other functions as arguments or return functions as their results. They enable functional programming paradigms like map, filter, and reduce.

Explain the concept of the “this” keyword in JavaScript.

It is one of the most commonly asked JavaScript this interview questions .

In JavaScript, the “this” keyword refers to the current execution context or the “owner” of the function being executed. The value of “this” is determined by how a function is called. It is not fixed and can change based on the invocation context.

What is the event loop in JavaScript, and how does it work?

The event loop is a mechanism that handles asynchronous operations in JavaScript. It continuously checks the call stack and task queue, moving tasks from the queue to the stack for execution when the stack is empty.

What is the difference between == and === in JavaScript?

== is used for loose equality comparison and performs type coercion if needed, while === is used for strict equality comparison (checking both value and type) without type coercion.

JavaScript Interview Questions for 5 Years Experience

Here are some important JS interview questions for candidates with 5 years of experience.

What are generators in JavaScript, and how are they used?

Generators are functions that can be paused and resumed at certain points using the yield keyword. They allow for asynchronous-like behaviour in synchronous code and are often used for iterative algorithms and handling streams of data.

Explain the concept of ES6 modules in JavaScript.

ES6 modules provide a way to organize and structure code into reusable components. They use import and export statements to define dependencies between modules, allowing for better code organization and maintainability.

How does JavaScript handle memory management and garbage collection?

JavaScript uses automatic memory management through garbage collection. It allocates memory when objects are created and automatically frees up memory when objects are no longer in use or unreachable by the program.

Common garbage collection algorithms include reference counting and mark-and-sweep.

What is the difference between function declaration and function expression?

Function declarations are hoisted and can be called before they are defined in the code, while function expressions are not hoisted and must be defined before they are called. Function expressions can also be anonymous (no function name).

What are some best practices for optimizing JavaScript performance?

Some best practices include,

Minimizing DOM manipulation
Using efficient data structures like arrays and objects
Reducing unnecessary function calls
Caching variables for reuse
Using browser developer tools to profile and optimize code

JavaScript Interview Questions for 10 Years Experience

Here are some important JavaScript interview questions for candidates with 10 years of experience.

What are the differences between classical inheritance and prototypal inheritance in JavaScript?

Classical inheritance involves defining classes and creating instances of those classes using constructors and inheritance hierarchies.

Prototypal inheritance, on the other hand, uses prototypes to share behaviour between objects, allowing for more flexible and dynamic object creation.

What are the advantages and disadvantages of using closures in JavaScript?

Closures in JavaScript allow functions to retain access to variables from their parent scopes, enabling encapsulation and private data.

However, excessive use of closures can lead to memory leaks if not managed properly, as they maintain references to outer scope variables.

What are some common design patterns used in JavaScript development?

Common design patterns in JavaScript include the Singleton pattern, Factory pattern, Module pattern, Observer pattern, and Promises pattern.

These patterns help in structuring and organizing code to promote reusability, maintainability, and scalability.

How does JavaScript handle error handling, and what are the best practices for managing errors in production code?

JavaScript uses try-catch blocks to handle synchronous errors and .catch() methods for handling Promise rejections in asynchronous code.

Best practices for managing errors include,

Logging errors with relevant information
Implementing graceful error recovery strategies
Using tools like error monitoring services to track and analyze production errors.

Advanced JavaScript Interview Questions

Take a look at these advanced JavaScript programming questions and answers .

Explain the concept of lexical scoping in JavaScript.

Lexical scoping in JavaScript means that the scope of a variable is determined by its position within the source code’s lexical structure. Inner functions have access to variables declared in their outer function’s scope.

What is the NaN property in JavaScript?

The NaN property in JavaScript represents a value that is “Not-a-Number.” It indicates that a value is not a valid number. If a calculation or operation results in a value that is not a number, it will return NaN.

To check if a value is NaN, you can use the isNaN() function. It’s important to know that isNaN() converts the given value to a number and then checks if it equals NaN.

What are the various types of errors in JavaScript?

JavaScript errors can be categorized into three types:

Load time errors : These errors occur while a web page is loading. They include syntax errors that are identified dynamically during the loading process.
Runtime errors : These errors happen when a command is used incorrectly in HTML.
Logical errors : These errors result from flawed logic within a function, leading to unexpected outcomes or incorrect behaviour during execution.
How is DOM used in JavaScript?

The DOM (Document Object Model) in JavaScript controls how different elements in a web page interact with each other.

It allows developers to manipulate objects like links and paragraphs on a web page, enabling actions such as adding or removing them dynamically. Using the DOM API simplifies web development compared to other models.

JavaScript Problem Solving Questions

These are some important problem-solving JavaScript interview questions and answers .

Find the maximum element in an array.

function findMaxElement(arr) {

if (arr.length === 0) {

return null; // Return null for empty array

}

let max = arr[0]; // Initialize max with the first element

for (let i = 1; i < arr.length; i++) {

if (arr[i] > max) {

max = arr[i]; // Update max if current element is greater

}

return max; // Return the maximum element

// Example usage:

let numbers = [10, 5, 8, 15, 3];

console.log(findMaxElement(numbers)); // Output: 15

Count the number of vowels in a given string.

function countVowels(str) {

const vowels = ‘aeiouAEIOU’;

let count = 0;

for (let char of str) {

if (vowels.includes(char)) {

count++;

return count;

let text = “Hello World”;

console.log(countVowels(text)); // Output: 3 (e, o, o)

Calculate the Fibonacci sequence up to n numbers using recursion.

function fibonacci(n) {

if (n <= 0) {

return [];

if (n === 1) {

return [0];

const sequence = [0, 1];

for (let i = 2; i < n; i++) {

sequence.push(sequence[i – 1] + sequence[i – 2]);

return sequence;

let count = 8;

console.log(fibonacci(count)); // Output: [0, 1, 1, 2, 3, 5, 8, 13]

JavaScript Object Oriented Programming Interview Questions

Here are some important JavaScript OOP interview questions and answers.

What is Object-Oriented Programming (OOP)?

Object-Oriented Programming (OOP) is a way of writing programs that use objects to structure and handle data. This approach emphasizes reusing code and breaking down complex tasks into simpler parts.

What are some benefits of using OOP in JavaScript?

Using Object-Oriented Programming (OOP) in JavaScript offers several advantages. It enhances code organization, promotes code reuse, and facilitates easier maintenance.

Additionally, OOP allows developers to model real-world objects and concepts more naturally within their codebase.

What is encapsulation in JavaScript?

Encapsulation is the bundling of data (attributes) and methods (functions) that operate on the data into a single unit called an object. It allows objects to control access to their internal state and hide implementation details from the outside world.

What is polymorphism in JavaScript?

Polymorphism allows objects of different classes to be treated as objects of a common superclass.

This means that different classes can implement the same method name but behave differently based on the specific class instance. Polymorphism enhances code reusability and flexibility in OOP.

JavaScript Coding Interview Questions

Here are commonly asked coding-related JavaScript practical questions and answers.

Write a function to check if a given string is a palindrome (reads the same backward as forward).

function isPalindrome(str) {

return str === str.split(”).reverse().join(”);

let text1 = “racecar”;

let text2 = “hello”;

console.log(isPalindrome(text1)); // Output: true

console.log(isPalindrome(text2)); // Output: false

Write a function to find the factorial of a number.

function factorial(n) {

if (n === 0 || n === 1) {

return 1;

let result = 1;

for (let i = 2; i <= n; i++) {

result *= i;

return result;

let num = 5;

console.log(factorial(num)); // Output: 120 (5! = 5 * 4 * 3 * 2 * 1)

Write a function to remove duplicate elements from an array.

function removeDuplicates(arr) {

return arr.filter((value, index, self) => self.indexOf(value) === index);

let nums = [1, 2, 2, 3, 4, 4, 5];

console.log(removeDuplicates(nums)); // Output: [1, 2, 3, 4, 5]

JavaScript MCQ Question and Answer

Here are some important JavaScript logical questions and answers.

What will the following code output?

console.log(typeof NaN);

A) “number”

B) “NaN”

C) “undefined”

D) “string”

Answer: A) “number”

Which keyword is used to declare a constant variable in JavaScript?

B) let

C) const

D) final

Answer: C) const

What does the setTimeout() function do in JavaScript?

A) Pauses the execution of the script

B) Sets a timer to execute a function after a specified delay

C) Executes a function immediately

D) Stops the execution of a function

Answer: B) Sets a timer to execute a function after a specified delay

Which of the following is NOT a valid JavaScript data type?

B) boolean

C) undefined

D) decimal

Answer: D) decimal

Question: What will the following code output?

console.log(2 + “2”);

B) “22”

C) “4”

D) NaN

Answer: B) “22”

Wrapping Up

So, these are the top 25+ JavaScript interview questions and answers that cover essential concepts and topics for JavaScript developers. Learning these questions will boost your confidence and help you impress the interviewers . And if you are looking for the latest JavaScript job opportunities, visit Hirist , the leading IT job portal in India.

Top 25+ Frontend Interview Questions and Answers

Top 35+ nodejs interview questions and answers, you may also like, top 20+ hashmap interview questions with answers, top 20+ java collections interview questions with answers, top 15+ typescript interview questions and answers, top 25 sap interview questions and answers.

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Download Interview guide PDF

Low level design interview questions, download pdf, introduction.

Generally, we develop software to solve a particular business problem. Developing any software follows a procedure as identifying the business problem, collecting the functional requirements for the identified problem, designing the overall architecture of the software/system by defining the building blocks called components, designing the individual components, actually writing the code, testing the software, deploy/release the software and maintain the software.

Before writing the actual code, we do 2 crucial steps. One is defining the high-level components typically called High-Level Design (HLD) and another is designing each component in detail typically called Low-Level Design (LLD).

What is High-Level Design (HLD)?

In HLD, the focus is more on designing the high-level architecture of the system, defining the high-level components with their interactions, and also the database design. HLD converts the business requirements to a high-level solution.

What is Low-Level Design (LLD)?

In LLD , the focus is more on designing each component in detail such as what classes are needed, what abstractions to use, how object creation should happen, how data flows between different objects, etc. LLD converts the high-level design into detailed design (ready to code) components.

It is common nowadays to have a Low-Level Design round (or) Pair Programming round (or) Machine Coding round in tech interviews.

In this article, we discuss why LLD is important, how to prepare for low-level design interview questions for freshers and experienced candidates with some examples, and finally conclude with some tips.

Low Level Design Interview Questions: Freshers & Experienced

1. why lld is important.

As a software developer in any company, the objective is to build software for the business of the company. Building software is a complex task. Change is the only constant thing in the world. As the software progresses over the years, it needs to incorporate a lot of changes as the requirements keep on changing. We can choose to build software in many ways but we need to build it in such a way that the software is maintainable and extensible over the years easily.

Most of the software developer interviews have Data Structures & Algorithms round(s). But it is not often for software developers to use these data structures and algorithms in the real world while building software. (If you are an experienced candidate, can you recall when was the last time you used the Dijkstra algorithm? If you are fresher, ask any of your senior colleagues the same question. )

On the other hand, Low-Level Design is a must for building a piece of software. As LLD focuses on how to build software from a set of requirements, how different components interact with each other, what responsibilities each component has etc, it is a vital exercise to be done before actually writing the code. Writing code is the easiest part of building software if we have the designs already in place. Maintaining and Extending software will be easy if designs are well thought of.

As we can see from the above picture, Maintenance takes almost 70% of the effort in the software development life cycle. So the software should be easily maintainable and extensible. LLD plays an important role in the design of software and hence directly contributes to the maintainability and extensibility of software.

2. How to prepare for Low-Level Design Interviews?

Software Developers need to learn Low-Level Design not only to crack the Interviews but also to build modular, extensible, reusable, and maintainable software. It is the thought process that developers need to develop to effectively build the software from a set of requirements.

Here is the list of things that a software developer needs to learn for LLD Interviews:

Object-Oriented Language : The general expectation in the machine coding round (or) LLD round is that candidate writes Object Oriented Code. As the name suggests, Object-Oriented Languages revolve around everything about Objects. The candidate should identify the different entities that need to be created from the problem statement and model the classes as per the required entities along with choosing the right set of data structures depending on the use case. Learning any Object-Oriented Language is a must as the candidate needs to write code using that language. Some of the popular Object-Oriented Languages are Java, C#, C++, and Python.
YAGNI : Y ou A in't G onna N eed I t is a practice in software development that states that features should only be added when required and thus help trim away excess and inefficiency development to facilitate the desired increased frequency of releases)
DRY : D on't R epeat Y ourself is a principle that states that don't repeat the code again and again. If there is a code that is duplicated then whenever a change needs to be made, the change has to be done in both places. So the developer has to remember all the places where the code is duplicated which are difficult and error-prone. Thus this principle states that the code should never be duplicated and has to refactor into its method or class and all other places need to use this method/class instead of duplicating the code.
SOLID : These are a set of 5 principles. S ingle Responsibility, O pen-Closed, L iskov Substitution, I nterface Segregation, and D ependency Inversion.

Apart from these, there are well-known principles such as favouring composition over inheritance, Encapsulating what varies, Striving for loosely coupled classes, etc.

Structural Diagrams: They represent the static view of the system. Class Diagram, Composite Structure Diagram, Object Diagram, Component Diagram, Deployment Diagram, Profile Diagram, and Package Diagram are part of Structural Diagrams.
Behavioural Diagrams: They represent the dynamic view of the system. Activity Diagram, State Machine Diagram, Use Case Diagram, Interaction Overview Diagram, Timing Diagram, Sequence Diagram, and Communication Diagram are part of Behavioral Diagrams.

Class Diagram & Use Case Diagram are generally used in LLD rounds.

Design Patterns : Design Patterns are typical solutions to common problems in software design. "Don't reinvent the wheel" is a well-known phrase in software engineering. If a problem is already solved, don't solve the same problem to get the same solution. Instead, use the solution to the problem. Similarly, there are a lot of common problems in software design that are solved and are given as a toolkit called Design Patterns. Design Patterns are not specific to a particular language. They are the general solutions that specify how a design problem can be solved and hence can be implemented in any language. These design patterns are proven and tested and hence make the development process smooth and easy.
Practice LLD Questions: Try to practice as many low-level design interview questions as possible. Solving different problems gives different perspectives and thereby improves design skills. There is no right solution for design problems as opposed to data structures and algorithmic problems. So solving different problems gives different ideas and thus develops the overall thought process for solving any design problem.

3. How to Solve Low-Level Design problems in Interviews?

Solving an LLD problem in an interview can be done easily if we divide the solution into multiple stages and focus on solving these stages one by one. LLD problems can be broadly categorized into 2 types: Standalone applications, and web applications.

Solving an LLD problem can be divided into mainly 3 stages:

1. Clarify & Gather Requirements: The low-level design interview questions are intentionally open-ended/ unstructured similar to real-life conditions. Ask the relevant questions regarding the problem (good questions are the ones that help to understand more about the system behaviour, features, and what features are expected to be added to the system in the future) and gather the complete requirements of the system. Don't assume anything beforehand and always clarify with the interview the assumptions you want to take. Write down the requirements & assumptions and discuss them with the interviewer.

2. Class Diagram & Use Case Diagram & Schema Diagram (If required): Once the requirements are gathered, define the core classes and objects, how the different classes interact with each other, and actors who interact with the system, the use cases for each actor, etc. Draw the class diagram and use a case diagram (can be optional, ask the interviewer) for the system. Define the relations between classes by observing the interactions between them. If Class Diagram & Use Case Diagram helps in representing the requirements of systems and the relationship between different classes, a Schema Diagram (also called an ER Diagram) helps in how the data models look and how to store the data in the database. Interviewers may not ask to write the code to store the data in the actual database but they may be interested in how the model looks like and the relationship between them. It is easy to create the Schema Diagram from the Class Diagram. Each class in the class diagram becomes a table in Schema Diagram and the relationship between classes becomes the multiplicity between tables.

3. Code: Finally once the thoughts are structured using Class Diagram, Use Case Diagram, and Schema Diagram (if required), the Candidate can start writing the code. Apply the Design Patterns, Object-Oriented Principles & SOLID Principles wherever is possible to make the system reusable, extensible, and maintainable. Make sure the code is well structured and follow the clean coding practices to make the classes and method clean. Don't try to fit design patterns to code but check if a given problem can be solved using any available design pattern. Take care of the readability of code while taking care of all of the above. Yes, software engineering is hard.

4. How to design Snake and Ladder?

Here is how the " Snake and Ladder problem " can be solved by using the above approach.

1. Gathering Requirements: Create a multiplayer Snake and Ladder game in such a way that the game should take input N from the user at the start of the game to create a board of size N x N. The board should have some snakes and ladders placed randomly in such a way the snake will have its head position at a higher number than the tail and ladder will have start position at smaller number than end position. Also, No ladder and snake create a cycle and no snake tail position has a ladder start position & vice versa.

The players take their turn one after another and during their turn, they roll the dice to get a random number and the player has to move forward that many positions. If the player ends up at a cell with the head of the snake, the player has to be punished and should go down to the cell that contains the tail of the same snake & If the player ends up at a cell with the start position of a ladder, the player has to be rewarded and should climb the ladder to reach the cell which has a top position of the ladder. Initially, each player is outside of the board (at position 0). If at any point of time, the player has to move outside of the board (say player at position 99 on a 100 cell board and dice rolls give 4) the player stays at the same position.

Possible future extension:

The game can be played by more than one dice. (i.e. if there are two dices then the numbers from 2 to 12 will be generated).
On getting a 6, you get another turn and on getting 3 consecutive 6s, all three of those get cancelled.

2. Class Diagram & Use Case Diagram:

3. Code Implementation:

Driver.java

GameStatus.java

SpecialEntity.java

Ladder.java

Player.java

GameAlreadyStartedException.java

It is important to structure the code into different classes with each class having a single responsibility (Remember S in SOLID Principles) and also having relations between the classes so that they can be easily extensible.

Some frequently asked low-level design examples to practice are:

Design Parking Lot
Design Splitwise
Design Tik Tok Toe Game
Design Car Rental System
Design Bookmyshow
Design Pub Sub System
Design Coffee Vending Machine

Tips on Cracking the Low Level Design (LLD) Interview

1. interview preparation tips.

Don't be in hurry: Once the requirements are listed, there may be too many requirements to consider and the 40 or 45 minutes may not be enough to design, and code. Don't be in a hurry to complete the design, and code for all of the requirements. Discuss with the interviewer and mention only the core requirements that you want to consider for the design. It is better to stand and drink water than drink milk by running.
Practice: Take out a low-level design problem and try to solve them all by yourself. Gather requirements (be your judge here), create class & schema diagrams and write code that is extensible, reusable, and maintainable. Once you complete solving the problem, look at different solutions for the same problem out there on the internet and improve the weakness. Practice as many problems as you can before the interview. If you are lucky, you may even get the problem you already solved in the interview. If not, you already have a thought process developed to solve any new problem. Win-Win situation
Plan for each stage: Unfortunately, it is not enough to solve the given problem, we also need to complete it within the time limit. As, we have different stages in solving the low-level design interview question like gathering requirements, class diagram, schema diagram, code, test, etc. Plan on how much percentage of interview time you want to spend on each stage. The more you practice, you may even analyze the time you are taking at each stage and check where you need to improve.
Write Testcases & Handle Exceptions: Not every interviewer expects you to write the test cases for the code. But if you can go a step further and write down the test cases, it gives you a huge advantage over other candidates. Gracefully handle exceptions and other corner cases.
Get comfortable with tools: As we may need to draw class diagrams, schema diagrams, use case diagrams, etc, design different components and their interaction between them, it is common that companies schedule their design interviews with whiteboard links & code editor. It may be difficult to use the whiteboard apps/ code editors without getting accustomed to them. So get comfortable with these tools before the interview so that you don't have to waste time figuring out how to do things with these tools.

In this article, we discussed what Low-Level Design is and how it is different from High-Level Design interviews. Low-Level Design focuses on the class-level design of an application & clean, readable, maintainable, and extensible code. No software is built for fixed requirements and as the software evolves there will be new requirements and hence the software needs to be changed. Change is the only constant in software development. Hence the software needs to have a good design. The key to cracking Low-Level Design interviews is to understand the importance & use of Object Oriented Principles and Design Patterns in the development of real-world applications and how these concepts make the application readable, maintainable, and extensible.

Clearly understand the low-level design problem, jot down the requirements of the problem, fine-tune the requirements and pick the core requirements that can be implemented in the given time, make note of different entities with their behaviours & actors from the core requirements, create the use case diagram and class diagram, make the schema diagram if the problem statement requires a type of web application to be built (no need to create a web application in an interview but the code can be structured in that way by creating controllers, services, and repositories) and then finally implementing the core features by using Object Oriented Principles and Design Patterns to make the application extensible and readable.

Practice as many low-level design interview questions as possible as each problem gives a different perspective and learn how to apply Object Oriented Principles and Design Patterns to solve the problems.

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Low level design mcq questions.

What does DRY stand for?

What does D in SOLID principles mean?

Which principle says that "a class should have a single reason to change"?

Which of the following is not a category of Design Pattern?

Which design pattern ensures that only one object of a particular class gets created?

What does the MVC pattern stands for?

Which of the below is not an Object Oriented Principle?

Which of the below is not a UML diagram?

Which of the following describes the Strategy pattern correctly?

In a Low-Level Design interview, which of the following options would be the correct sequence to follow?

Statements:

Statement I: Specifying the core requirements to be included.
Statement II: Create a class diagram & use a case diagram.
Statement III: Clarifying any doubts with regards to the question asked.
Statement IV: Implement the code using Object Oriented Principles & Design Patterns.
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Since coding and problem solving are an important part of any programming job interview, it's imperative that you know how to solve them in time and in a pressure situation, which comes only after doing practice with the right set of questions. ... That's all about some frequently asked String Programming interview questions for preparing ...
Top 21 String Programming Interview Questions for Beginners and
Other Interview Questions articles you may like:. Here are a few more collection of topic-based interview questions you may like to see: 20+ linked list problems from interviews 20+ basic ...
Top 25 String Manipulation Interview Questions and Answers
The first method is to use a for loop. Initialize a counter variable at zero, then iterate over each character in the string, incrementing the counter by one each time. At the end of the loop, the counter will hold the length of the string. The second method involves using the reduce function from the functools module.
Top Java String Interview Questions & Answers (2024)
Java offers both the equals () method and the "==" operator for comparing objects. However, here are some differences between the two: Essentially, equals () is a method, while == is an operator. The == operator can be used for comparing references (addresses) and the .equals () method can be used to compare content.
String cheatsheet for coding interviews
Sorting both strings should produce the same resulting string. This takes O (n.log (n)) time and O (log (n)) space. If we map each character to a prime number and we multiply each mapped number together, anagrams should have the same multiple (prime factor decomposition). This takes O (n) time and O (1) space.
Top 20 String Coding Problems from Programming Job Interviews
3. JavaScript Algorithms and Data Structures Masterclass by Colt Steele for JavaScript programmers. 4. Mastering Data Structures & Algorithms using C and C++ for those who are good at C/C++. These are some of the best courses on data structures and algorithms and you can choose the one which is most suitable for you.
String Manipulation Interview Questions
How many characters should one delete to make two given strings anagrams of each other? Solve Challenge. Alternating Characters ... Interview Preparation Kit. String Manipulation. String Manipulation ... Easy Problem Solving (Basic) Max Score: 20 Success Rate: 97.45%. Solve Challenge. Sherlock and the Valid String. Medium Problem Solving (Basic ...
Java String Interview Questions
To improve memory consumption and performance, Java 9 introduced compact Strings.This means that if a String contains only 1-byte characters, it will be represented using Latin-1 encoding. If a String contains at least 1 multi-byte character, it will be represented as 2 bytes per character using UTF-16 encoding.. In C and C++, String is also an array of characters, but in Java, it's a ...
String Cheatsheet for Coding Interview Prep
Most string problems use the same problem-solving patterns that we talked about for arrays. Here are the question types you may encounter: In a lot of questions, you need to count the number of ...
How I Master String Coding Problems for Interviews
Level 1 — Easy (Must Prepare) I have listed the 15 most asked coding interview string questions. Palindromic Substring. Decode String. Reverse Words in a string. Valid Parentheses. Find all ...
Strings
Strings. This lesson discusses String interview questions in Java. Level up your interview prep. Join Educative to access 70+ hands-on prep courses. Start Learning. This lesson discusses String interview questions in Java.
String
Following is the list of commonly asked string interview questions: Check if a string is a rotated palindrome or not Medium. Longest Palindromic Substring Problem Medium. Check if a repeated subsequence is present in a string or not Hard. Check if strings can be derived from each other by circularly rotating them Easy.
Strings : Popular Interview Problems
In this playlist, we will solve and understand popular problems on Strings asked by Top Companies like - Amazon, - Meta, - Google, - Microsoft, - Adobe, - Ne...
Java String FAQs and Interview Questions
Java String FAQs or Interview Questions. A list of top Java String FAQs (Frequently Asked Questions) or interview questions are given below. These questions can be asked by the interviewer. 1) How many objects will be created in the following code? String s1="javatpoint"; String s2="javatpoint";
15 Common Problem-Solving Interview Questions
Here are a few examples of technical problem-solving questions: 1. Mini-Max Sum. This well-known challenge, which asks the interviewee to find the maximum and minimum sum among an array of given numbers, is based on a basic but important programming concept called sorting, as well as integer overflow.
Better String
In this comprehensive tutorial, we dissect the Better String problem, exploring its intricacies and providing step-by-step guidance on how to solve it efficiently. Whether you're a coding enthusiast, a student brushing up on DSA concepts, or a professional developer seeking to enhance your problem-solving skills, this video is for you.
Top 20 Problem Solving Interview Questions (Example Answers Included)
MIKE'S TIP: When you're answering this question, quantify the details. This gives your answer critical context and scale, showcasing the degree of challenge and strength of the accomplishment. That way, your answer is powerful, compelling, and, above all, thorough. 2. Describe a time where you made a mistake.
50 Interview Questions About Problem Solving (With Answers)
Demonstrating your ability to tackle challenges effectively can set you apart from other applicants. Here are five tips to help you showcase your problem-solving skills during an interview: 1. Use the STAR Method. Structure your responses using the Situation, Task, Action, and Result (STAR) method.
25+ JavaScript Coding Interview Questions (SOLVED with CODE)
FullStack.Cafe is a biggest hand-picked collection of top Full-Stack, Coding, Data Structures & System Design Interview Questions to land 6-figure job offer in no time. Check 25+ JavaScript Coding Interview Questions (SOLVED with CODE) and Land Your Next Six-Figure Job Offer! 100% Tech Interview Success!
Check if strings are rotations of each other or not
Embark on a journey through string manipulation and algorithmic analysis with this insightful guide from GeeksforGeeks. In this illuminating article, you'll explore the task of determining if two strings are rotations of each other—an essential problem in string processing with applications in text comparison, pattern recognition, and algorithmic design.
50 String Coding Questions Using Python
First, the code assigns the string '50 String Coding Questions Using Python' to the variable string1. Next, the startswith() method is used to determine if string1 starts with the substring ...
8 Common Problem-Solving Interview Questions and Answers
Problem-solving interview questions are questions that employers ask related to the candidate's ability to gather data, analyze a problem, weigh the pros and cons and reach a logical decision. Also known as analytical skills interview questions, these questions will often focus on specific instances when the candidate analyzed a situation or ...
Top 25+ JavaScript Interview Questions and Answers
JavaScript Problem Solving Questions. These are some important problem-solving JavaScript interview questions and answers. Find the maximum element in an array. function findMaxElement(arr) ... Write a function to check if a given string is a palindrome (reads the same backward as forward). function isPalindrome(str) ...
Wildcard string matching
Prepare to elevate your problem-solving skills and algorithmic proficiency as you explore detailed explanations and practical examples for wildcard character matching. Unlock the full potential of string processing and pattern matching in your projects by delving into the accompanying article on GeeksforGeeks: https://www.geeksforgeeks.org ...
Low Level Design Interview Questions
Solving an LLD problem in an interview can be done easily if we divide the solution into multiple stages and focus on solving these stages one by one. LLD problems can be broadly categorized into 2 types: Standalone applications, and web applications. Solving an LLD problem can be divided into mainly 3 stages: 1.
Fundamental Coding Interview Preparation with Python
Immerse yourself in the comprehensive world of Python programming to navigate the challenges of technical assessments at renowned tech companies. This course focuses on Python, aiming to prepare you with a solid knowledge of Python syntax, algorithms, data structures, and problem-solving strategies meticulously compiled to improve your coding aptitude. Tailored to strengthen your coding ...
Find the String
Embark on a journey through string manipulation and algorithmic optimization with this insightful guide from GeeksforGeeks. In this illuminating article, you'll explore the task of constructing the minimum length string containing all substrings of size n—an essential problem in string processing with applications in text compression, data encoding, and algorithmic design.
Reverse words in a given string
Embark on a journey through string manipulation with this insightful guide from GeeksforGeeks on reversing words in a given string. In this illuminating article, you'll explore essential concepts and algorithms for efficiently reversing the order of words within a string, a critical skill for various applications such as text processing, natural language processing, and data analysis.