programming problem solving questions and answers

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Top 75 Programming Interview Questions Answers to Crack Any Coding Job Interview

Top 50 coding interview questions for programmers (2023), 1. array-based programming interview questions.

I say "hey guys..." in much the same way a southerner says "ya'll", it's just a plural for a group. Stop turning everything into a problem.

Yeah, about time, I change my style and start saying "Hello all", thanks a lot.

Sorry, I didn't mean that. It's just my casual way to start the article. I very much appreciate woman in tech and female software engineer. About time, I change my style to say "Hello All" instead of of "Hello Guys". Thanks

Hey feminist, it is just a word. Really you are going to get offended and discount everything that the page says because of one word? A real strong woman would move past it and realize the interview questions included within are actually quite good and detailed and probably will prepare you quite well for a job interview. Instead you are so concerned about the word "guys" at the top. Did you ever notice how actual guys don't spend time worrying about trivial things and just focus on getting the job done. Try that instead.

All the lady engineers who get help from male engineers should remember to give back. Time and again, my experience with female engineers at conferences has been very poor. There is no sharing of knowledge. It cannot be one way street in the name of equality. Two, please respect the author who works for the whole community, rather than nit-picking over political correctness. Three, have courage to post a comment like this with your own signature, not anonymously. :-)

Oh please, if you respected women in the industry, you wouldn't be so critical of them. I agree with the poster. The terminology should be more inclusive. It's a matter of respect.

omg, you fight each other just for "hello guys" words ?

Very useful..Thanks..!!

Good work..

This is a great list of problems, but I believe readers should look elsewhere for correct solutions. I haven't opened all of them, but some of them (e.g. "remove duplicate chars from string", "find square root of a number") have some pretty bizarre solutions.

for square root I can understand but remove duplicate character from string seems straightforward, no?

Maybe you should "hello world" instead!

Wow... I'm about 10 years into the developer job and not able to solve many of these question. Think I should quit my job :(

You are not alone it happened to everybody. You just need a bit of practice and you will be fine.

Thanks - but what to practice is the key question :)

I just came here to read the comments. You guys have become popular, cheers !

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

100+ Coding Interview Questions for Programmers and Software Engineers in 2024

Solve these frequently asked coding problems to do well on your next programming job interviews..

Coding Interviews are such an important thing in a programmer’s life that he just can’t get away with that. It’s the first hurdle they need to cross to get the software developer job they wish throughout their school and college days.

To make the matter worse, you will find that so many people on the internet telling that coding interview is flawed, the hiring process for programmers sucks, and so on but you don’t need to pay attention to them, not at least at the start of your career.

They may be right but they are inside the train which you are trying to get into. No matter, how much they criticize the coding interviews and programmers hiring process, many of them have gone through the same route to where they are.

We all know that Coding Interview System is not perfect and many are trying to change it but until it's changed, you got to follow its rules to get into the System. This is something for experience developers to deal with, as a junior developer your priority should be to clear the coding interview and get the job you want.

As an author of a Java blog and a Medium publication , I receive a lot of queries related to coding problems and how to deal with them and that’s why I keep writing articles like this which have helped a lot of programmers directly and in-directly in their career.

In this article, I am going to share with you the top 100 coding interview problems from programming job interviews which every programmer should know.

What to prepare for Coding Interviews?

Now that, I have cleared the confusion that Coding interviews is important and you should not distract, let’s get into real work. The big question is what to prepare for Coding interviews?

Well, the most important thing to prepare is Data Structure-based coding problems like array-based coding problems, string problems, linked list problems, binary tree problems, etc.

Apart from data structure-based questions, most of the programming job interviews also ask algorithm, design, bit manipulation, and general logic-based questions, which I’ll describe in this section.

It’s important that you practice these concepts because sometimes they become tricky to solve in the actual interview. Having practiced them before not only makes you familiar with them but also gives you more confidence in explaining the solution to the interviewer.

One of the main problems with coding problems is that there are hundreds and thousands of coding problems on interviews, there are even sites like LeetCode , HackerRank , Codewars , Topcoder , freeCodeCamp , HackerEarth which train programmers for coding interviews with lots of tough questions, which sometimes just overwhelms a beginner looking for a job.

I believe in simplicity and the 10% of effort which produce 90% of results and that’s why I have collected top 100 coding problems which are not too tough and also frequently asked on real interviews.

Solving these problems not only gives you confidence but also helps you to recognize some of the most common algorithmic patterns which will also help you to solve some unseen problems in real interviews.

Best Resources for Coding Interviews

The selection of good resources is very important for success in your coding interviews. If you chose the wrong resource then more than money, you will lose the valuable time you need for preparation, hence spending some time researching for a good resource.

If you need recommendations, the following are some of my the tried and tested resources to learn Data Structure and Algorithms in-depth for coding interviews:

• Data Structures and Algorithms: Deep Dive Using Java for Java developers. Learn about Arrays, Linked Lists, Trees, Hashtables, Stacks, Queues, Heaps, Sort algorithms, and Search algorithms

Data Structures and Algorithms: Deep Dive Using Java

So you've worked with the basics of data structures and algorithms in java (or another oo programming language) but….

• Algorithms and Data Structures in Python for those who love Python A guide to implementing the most up to date algorithms from scratch: arrays, linked lists, graph algorithms, and sorting

Algorithms and Data Structures in Python

This course is about data structures and algorithms. we are going to implement the problems in python. i highly….

• JavaScript Algorithms and Data Structures Masterclass by Colt_Steele for JavaScript programmers. The Missing Computer Science and Coding Interview Bootcamp. Learn everything you need to ace difficult coding interviews.

JavaScript Algorithms and Data Structures Masterclass

This course crams months of computer science and interview prep material into 20 hours of video. the content is based….

• Mastering Data Structures & Algorithms using C and C++ for those who are good at C/C++
• Data Structures in Java: An Interview Refresher by The Educative Team to refresh important Data Structure and algorithms concepts in Java. This course contains a detailed review of all the common data structures and provides implementation-level details in Java to allow readers to become well equipped.
• Grokking the Coding Interview: Patterns for Coding Questions by Fahim ul Haq and The Educative Team This is like the meta course for coding interviews, which will not teach you how to solve a coding problem but, instead, teach you how to solve a particular type of coding problem using patterns. Master these 15 underlying patterns to interview questions, and you’ll be able to tackle anything you face on the interview

Grokking the Coding Interview: Patterns for Coding Questions

Coding interviews are getting harder every day. a few years back, brushing up on key data structures and going through….

www.educative.io

System Design is another topic which is quite important for coding interviews and when it comes to System design , there are not many places where you can learn System design concepts and architecture in depth, but ByteByteGo is exceptional.

ByteByteGo | Ace Your Next System Design Interview

Everything you need to take your system design skill to the next level.

bytebytego.com

It’s one of those sites where I have learned a lot. They explain many key System design concept like Microservices , load balancing, caching, Algorithms like CAP theorem and how to design a particular system with easily digestible diagram. It’s created by Alex Xu, author of System Design Interview — An insider’s guide , one of the best System Design book , and I highly recommend this to everyone preparing for coding interviews.

System Design Interview - An insider's guide

Buy system design interview - an insider's guide on amazon.com ✓ free shipping on qualified orders.

www.amazon.com

And, if you prefer books, there is no better than the Cracking The Coding Interview , by Gayle Laakmann McDowell which presents 189+ Programming questions and solutions. A good book to prepare for programming job interviews in a short time. Btw, I will also earn some money if you buy any of these resources mentioned here.

5 Best Tips to Crack Coding Interviews in 2023

Here are a few of my practical tips to crack your next coding interview. These are hard-earned and I learned from my own mistakes and experience.

• There is no better way to do well in Coding interviews than practicing as many coding problems as possible. This will not only train your mind to recognize algorithmic patterns in problems but also give you the much-needed confidence to solve problems you have never seen before.
• My second tips are to learn about as many data structure and algorithms as possible. This is an extension of the previous tip but it also involves reading and not just practicing. For example, If you know about the hash table you can also many array and counter-based problems easily. The same is true for trees and graphs.
• Choosing the right data structure is a very important part of software development and coding interview and unless and until you know them, you won’t be able to choose.
• Time yourself — candidates who solve interview problems within the time limit and quickly are more likely to do well in the interview so you should also time yourself.
• Think of edge cases and run your code through them. Some good edge cases might be the empty input, some weird input, or some really large input to test the boundary conditions and limits.
• After solving the problem, try explaining it to a friend or colleague how is also interested in coding problems. This will tell you whether you have really understood the problem or not. If you can explain easily means you understood . Also, the discussion makes your mind work and you could come up with an alternative solution and be able to find some flaws in your existing algorithms.
• Another useful tip to excel in Coding interviews is to appear in the coding interview and lots of them. You will find yourself getting better after every interview and this also helps you to get multiple offers which further allows you to better negotiate and get those extra 30K to 50K which you generally leave on a table if you just have one offer in hand.
• Btw, If you are ready for Coding Interview then you can also take TripleByte’s quiz and go directly to the final round of interviews with top tech companies like Coursera , Adobe Acrobat , Dropbox , Grammarly , Uber , Quora , Evernote , Twitch , and many more. I didn’t know about Triplebyte before, but they are providing a great service to job seekers. A big thanks to them.

Triplebyte: Software Engineer Job Search

Take a quiz. get offers from multiple top tech companies at once..

triplebyte.com

Top 100 Coding Problems from Programming Job interviews

Without wasting any more of your time, here is my list of 100 frequently asked coding problems from programming job interviews. In order to get most of this list, I suggest actually solving the problem.

Do it yourself, no matter whether you are stuck because that’s the only way to learn. After solving a couple of problems you will gain confidence.

I also suggest you look at the solution when you are stuck or after you have solved the problem, this way you learn to compare different solutions and how to approach a problem from a different angle.

• How is a bubble sort algorithm implemented? ( solution )
• How is a merge sort algorithm implemented? ( 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 implement a bucket sort algorithm? ( solution )
• How do you implement a counting sort algorithm? ( solution )
• How do you remove duplicates from an array in place? ( solution )
• How do you reverse an array in place in Java? ( solution )
• How are duplicates removed from an array without using any library? ( solution )
• How is a radix sort algorithm implemented? ( solution )
• How do you swap two numbers without using the third variable? ( solution )
• How do you check if two rectangles overlap with each other? ( solution )
• How do you design a vending machine? ( solution )
• How do you find the missing number in a given integer array of 1 to 100? ( solution )
• How do you find the duplicate number on a given integer array? ( solution )
• How do you find duplicate numbers in an array if it contains multiple duplicates? ( solution )
• Difference between a stable and unstable sorting algorithm? ( answer )
• How is an iterative quicksort algorithm implemented? ( solution )
• How do you find the largest and smallest number in an unsorted integer array? ( solution )
• How do you reverse a linked list in place? (solution)
• How to add an element at the middle of the linked list? (solution)
• How do you sort a linked list in Java? ( solution )
• How do you find all pairs of an integer array whose sum is equal to a given number? ( solution )
• How do you implement an insertion sort algorithm? ( solution )
• How are duplicates removed from a given array in Java? ( solution )
• how to remove the duplicate character from String? ( solution )
• How to find the maximum occurring character in a given String? ( solution )
• How is an integer array sorted in place using the quicksort algorithm? ( solution )
• 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 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 do you check if a string contains only digits? ( solution )
• How to remove Nth Node from the end of a linked list? ( solution )
• How to merge two sorted linked lists? (solution)
• How to convert a sorted list to a binary search tree? ( 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 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 to convert a byte array to String? ( solution )
• How do you remove a given character from String? ( solution )
• How do you find the middle element of a singly linked list in one pass? ( solution )
• How do you check if a given linked list contains a cycle? How do you find the starting node of the cycle? ( solution )
• How do you reverse a linked list? ( solution )
• How do you reverse a singly linked list without recursion? ( solution )
• How are duplicate nodes removed in an unsorted linked list? ( solution )
• How do you find the length of a singly linked list? ( solution )
• How do you find the third node from the end in a singly linked list? ( solution )
• How do you find the sum of two linked lists using Stack? ( solution )
• What is the difference between array and linked list? ( answer )
• How to remove duplicates from a sorted linked list? ( solution )
• How to find the node at which the intersection of two singly linked lists begins. ( solution )
• Given a linked list and a value x , partition it such that all nodes less than x come before nodes greater than or equal to x . ( solution )
• How to check if a given linked list is a palindrome? (solution)
• How to remove all elements from a linked list of integers which matches with given value? (solution)
• How is a binary search tree implemented? ( solution )
• How do you perform preorder traversal in a given binary tree? ( solution )
• How do you traverse a given binary tree in preorder without recursion? ( solution )
• How do you perform an inorder traversal in a given binary tree? ( solution )
• How do you print all nodes of a given binary tree using inorder traversal without recursion? ( solution )
• How do you implement a postorder traversal algorithm? ( solution )
• How do you traverse a binary tree in postorder traversal without recursion? ( solution )
• How are all leaves of a binary search tree printed? ( solution )
• How do you count a number of leaf nodes in a given binary tree? ( solution )
• How do you perform a binary search in a given array? ( solution )
• How to Swap two numbers without using the third variable? ( solution )
• How to check if two rectangles overlap with each other? ( solution )
• How to design a Vending Machine? ( solution )
• How to implement an LRU Cache in your favorite programming language? ( solution )
• How to check if a given number is a Palindrome? ( solution )
• How to check if a given number is an Armstrong number? ( solution )
• How to find all prime factors of a given number? ( solution )
• How to check if a given number is positive or negative in Java? ( solution )
• How to find the largest prime factor of a given integral number? ( solution )
• How to print all prime numbers up to a given number? ( solution )
• How to print Floyd’s triangle? ( solution )
• How to print Pascal’s triangle? ( solution )
• How to calculate the square root of a given number? ( solution )
• How to check if the given number is a prime number? ( solution )
• How to add two numbers without using the plus operator in Java? ( solution )
• How to check if a given number is even/odd without using the Arithmetic operator? ( solution )
• How to print a given Pyramid structure? ( solution )
• How to find the highest repeating world from a given file in Java? ( solution )
• How to reverse a given Integer in Java? ( solution )
• How to convert a decimal number to binary in Java? ( solution )
• How to check if a given year is a leap year in Java? ( solution )
• Can you implement a Binary search Algorithm without recursion? ( solution )
• What is Depth First Search Algorithm for a binary tree? (solution)
• What is the difference between Comparison and Non-Comparison Sorting Algorithms? ( answer )
• How do implement Sieve of Eratosthenes Algorithms for Prime Number? ( solution )

These many questions should be enough but If you need more such coding questions you can take help from books like Cracking The Code Interview , by Gayle Laakmann McDowell which presents 189+ Programming questions and solutions. A good book to prepare for programming job interviews in a short time.

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 blog , so if you are really interested, you can always go there and search for them.

These common coding, data structure, and algorithm questions are the ones you need to know to successfully interview any company, big or small, for any level of programming job.

If you are looking for a programming or software development job in 2024, you can start your preparation with this list of coding questions and if you are ready for an Interview then you can also take TripleByte’s quiz and go directly to the final round of interviews with top tech companies like Coursera, Adobe, Dropbox, Grammarly, and many more.

This list 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 Data Structures and Algorithms: Deep Dive Using Java 10 Books to Prepare Technical Programming/Coding Job Interviews 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 20+ String based coding problems from interviews 20+ linked list problems from interviews 20+ basic algorithms based problems from interviews ByteByteGo for System Design and Architecture

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 by following these searching and sorting algorithm questions, you are one step closer than others. By the way, the more questions you solve in practice, the better your preparation will be.

So, if you think 100 coding problems are not enough and you need more, then check out these additional 50 programming questions for telephone interviews and these books and courses for more thorough preparation.

All the best for your coding interview.

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• Basics of Input/Output
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10 Common Coding Interview Problems [Solved]

Are you preparing for coding interviews? Or competitive programming? It can take a lot of study and practice to get good at solving coding problems often used in interviews. We just published a course on the freeCodeCamp.org YouTube channel that will teach you how to solve 10 common coding problems and improve your problem-solving skills.

This course was developed Inside code. He is an experienced developer and has a good understanding of the types of coding challenges often used in programmer interviews.

The course uses graphics and animation to help you understand the theory behind the solutions. You will be able to apply what you learn to all sorts of coding challenges.

You will learn how to solve the following problems.

• Valid anagram
• First and last index in sorted array
• Kth largest element
• Symmetric tree
• Generate parentheses
• Gas station
• Course schedule
• Kth permutation
• Minimum window substring
• Largest rectangle in histogram

Watch the full course below or on the freeCodeCamp.org YouTube channel (2-hour watch).

I'm a teacher and developer with freeCodeCamp.org. I run the freeCodeCamp.org YouTube channel.

If you read this far, thank the author to show them you care. Say Thanks

Learn to code for free. freeCodeCamp's open source curriculum has helped more than 40,000 people get jobs as developers. Get started

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• Career Development

50+ Best Programming Interview Questions and Answers in 2024

Big firms like Amazon, Google, and Microsoft are always on the hunt to add programming and software development talent to join their rolls. So, in order to bag a lucrative opportunity at big names like the aforementioned, one needs to accumulate as much knowledge as possible.

In order to ease your endeavour, we have compiled a list of top programming interview questions that anyone aiming for programming interview questions must know.

• Top Programming Interview Questions and Answers

So, without any further ado, here we go:

Question: Please explain what you understand by computer programming.

Answer: Also known as coding or programming, computer programming is the process of encoding an algorithm into a notation, typically a computer program, by means of some programming language so that it can be executed by a computer.

Each programming language contains a set of instructions for the computer to execute a set of tasks. Programming is a complex process that includes designing an algorithm, coding the same in a programming language, debugging a program, maintaining, and updating the code.

Question: Can you enumerate and explain the various types of errors that can occur during the execution of a computer program?

Answer: Three types of errors can occur during the execution of a computer program. These are:

• Logical errors – This occurs in the scenario of a computer program implementing the wrong logic. As there is no report generated for these types of programming errors, they are the most difficult ones to deal with.
• Runtime errors – Occurs when the program contains an illegal operation. For example, dividing a number by 0. These are the only errors that are displayed instantly during the program execution. Upon the occurrence of a runtime error, the program execution is stopped and a diagnostic message is displayed.
• Syntax errors – Occurs when one or more grammatical rules of the programming language being used is violated. Such errors are detected during compile time.

Question: Please explain an algorithm. What are some of its important features?

Answer: An algorithm can be defined as a set of finite steps that when followed helps in accomplishing a particular task. Important features of an algorithm are clarity, efficiency, and finiteness.

Question: What do you understand by maintaining and updating a computer program?

Answer: The maintenance and updating process of a computer program starts post its successful installation. While program maintenance is the continuous process of monitoring the computer program for bugs and errors, updating the computer program means making it better with minor and major changes over time.

Question: Please provide a brief explanation on variables.

Answer: Variables are used for storing the input of a program as well as the computational results during program execution. These are actually named memory locations. The value stored in a variable can change during the program execution.

Question: Every programming language has reserved words. What are they? Give some examples.

Answer: Reserved words, also known as keywords, are the words that have predefined meanings in a particular programming language. These reserved words can’t be used or redefined for serving other purposes. Following are some examples of reserved words:

• C – break, case, char, default, else, float, if, and int
• Java – abstract, boolean, catch, class, const, double, enum, finally, implements, instanceof, throws, transient, and volatile
• Python – and, assert, continue, def, del, global, not, lambda, raise, and yield

Question: What do you understand by loops? Briefly explain the various types of loops.

Answer: A loop is a structure in programming that can repeat a defined set of statements for a set number of times or until a particular condition is satisfied. There are three important types of loops:

• FOR…NEXT Loop – This is the most effective loop when you know beforehand the total number of times the loop is to be repeated
• WHILE…WEND Loop – It keeps on repeating a particular action until the concerned condition becomes false. This loop is particularly useful when the total number of repetitions is unknown.
• Nested Loop – When a loop is used inside a loop then it is termed as a nested loop

Question: Please explain program documentation. Why is it important?

Answer: Program documentation is the written description of the algorithm(s), coding method, design, testing, and proper use of a particular computer program. It is valuable for those who use the program on a day-to-day basis and also for the programmer(s) who are meant to correct, modify, and update the computer program.

Reliable documentation is a must for an earnest programmer. The availability of thorough documentation helps not only in keeping track of the various aspects of a computer application but also helps in improving the overall quality of the same. The main focus of program documentation is development, maintenance, and knowledge transfer to other developers.

Question: What are constants? Explain their types.

Answer: A constant is a programming entity whose value can’t be changed or modified during program execution. Constants are of two main types:

• Numeric constants – Includes integers, single-precision, and double-precision numbers. For example, 22, 24, -898, 4.5, and 73.45
• String constants – Includes a sequence of alphanumeric characters enclosed in double quotation marks. The maximum length of a string constant is 255 characters. For example, “Shimla,” “I Love You,” and “Orange Is the New Black”

Question: Please explain the operators.

Answer: Operators are used for performing certain operations on data in a computer program. These are represented by symbols. For example, / represent mathematical division while * represents multiplication. There are 4 main types of operators:

• Arithmetic – Used for carrying out mathematical operations
• Assignment – Used for storing computational results, strings, and values in variables
• Logical – Used for allowing a computer program to make a decision based on multiple conditions. In other words, logical operators allow combining simple conditions to form more complex conditions
• Relational – Used for defining or testing some kind of relation between two entities. These operators evaluate to either true or false and produce a non-zero value

Question: Could you explain arrays?

Answer: An array is a programming structure that is a collection of several data values of the same type. In terms of memory, an array is a group of contiguous memory locations storing data of the same type.

Question: What do you understand by a subroutine?

Answer: A self-contained set of statements usable from anywhere in a computer program is known as a subroutine. Once the subroutine successfully performs its intended task it returns the control to the section of the program called the subroutine.

Question: Explain low-level and high-level programming languages. Also, give some examples.

Answer: Any programming language that offers no generalization from the computer’s instruction set architecture is a low-level programming language. Assembly language and machine language are two typical examples of low-level programming languages.

A programming language that offers high generalization from the computer’s instruction set architecture is termed a high-level programming language. Typically, a high-level programming language has elements resembling natural language to make program development easier.

Another definition of a high-level programming language is one that is independent of the underlying processor of the system in which it is running. C++, Java, and Python are some of the most popular high-level programming languages.

Question: What do you understand by machine code?

Answer: Machine code is a low-level programming language. Unlike high-level programming languages that come with a compiler to transform high-level code into machine code for execution, a microprocessor directly processes machine code without doing such a transformation.

Question: Do you know about modeling languages? Give some examples.

Answer: Any artificial language usable for expressing information or knowledge or systems in an arrangement determined by a reliable set of rules is called a modeling language.

The same set of rules is also used for interpreting the meaning of the components of a modeling language structure. Following are some examples of modeling languages:

• Business Process Modeling Notation
• Extended Enterprise Modeling Language
• Jackson Structured Programming
• Systems Modeling Language
• Unified Modeling Language

Question: Please explain software testing. Why do we need it?

Answer: Like programming, software testing is an important aspect of any software development life cycle model, whether it be the traditional waterfall model or the modern Rapid Application Development (RAD) model .

Under the process of software testing, the software is tested in certain conditions to check for the quality of the same. Another important motive for testing a computer program is to assess whether it succeeds in delivering a good user experience or not. Some other reasons include:

• Checking for improvements
• Ensure proper/intended working
• Meeting user requirements

Question: What do you mean by “beta version” of a computer program?

Answer: The beat version of a computer program or software is a release of the same that isn’t yet ready for public release and is meant to be modified after user feedback received from beta testing.

Question: Can you explain the top-down design approach?

Answer: The top-down design approach is a methodology adopted for analyzing software. Instead of tackling a problem as a whole, it is first divided into a number of sub-problems. Each of them is then solved individually. The solutions are then combined to get the best solution.

Question: What do you understand by program implementation?

Answer: Post the successful completion of software testing of a computer program, it needs to be installed and put into operation on the targeted computer(s). This process of installing and setting up the computer program to be used by end-users is termed as program implementation.

Question: Please explain program execution.

Answer: Program execution is the process of carrying out instructions innate to the program by the computer. Before execution, the computer program is required to be loaded into the memory (RAM) of the computer.

Question: What is a compiler?

Answer: A compiler is a computer program that translates written code in one programming language into another language. Typically, compiler refers to a program that translates source code pertaining to a high-level programming language to a lower-level programming language for creating an executable program.

Question: What is debugging? How is it related to testing?

Answer: During the testing of a computer program, a number of issues are discovered. These are called errors and bugs. Debugging is the process of correcting them. In other words, debugging is the process of correcting the failures discovered in the implemented code.

Question: Why do adding comments to code is highly recommended?

Answer: Any typical computer program contains hundreds to thousands of LOC. Adding comments is a way to simplify the experience of examining or finding something within the code easier for others.

Question: Can you enumerate some coding best practices?

Answer: Following are some coding best practices to make programming efficient:

• Abide by the DRY principle
• Follow some easy-to-remember naming convention
• Keep the code as straightforward as possible
• Limit the length of a line of code
• Use comments frequently
• Use consistent indentation
• Whenever and wherever possible, avoid deep nesting

Question: Can you please explain the DRY principle?

Answer: DRY stands for Don’t Repeat Yourself. It is a software development principle that aims at reducing the repetition of software patterns. For achieving this, either the repetitive software patterns need to be replaced with abstractions or data normalization must be used.

Question: What are the violations of the DRY principle called? Where are they found typically?

Answer: They are termed WET solutions. Although WET typically stands for Write Everything Twice, in some cases it might also mean We Enjoy Typing or Waste Everyone’s Time. WET solutions are usually adopted in multi-tiered architectures.

Question: Please explain bubble sorting?

Answer: Bubble sorting is a simple sorting algorithm in which adjacent elements in a data structure, such as an array, are continuously compared until we get the right order. The compared elements are swapped only if they are in the wrong order.

Bubble sort allows the smaller values to “bubble” to the top of the list, and hence the name. It is also called a sinking sort because of the bigger values “sink” to the bottom. See how does Bubble sort in C works.

Question: Please explain data structures.

Answer: A data structure is a particular way of organizing and manipulating data. It allows efficient access as well as modification of data.

A data structure can also be defined as a collection of data, the functions applicable to them, and the relationships among them. Arrays, linked lists, heaps, graphs, and stacks are some examples of data structures.

Question: What are some of the areas that leverage data structures?

Answer: Data structures are required about everywhere where data is involved. However, some notable examples are:

• Artificial intelligence
• Compiler design
• Database management
• Numerical analysis
• Operating systems
• Statistical analysis

Question: What do you understand by sorting? Name some popular sorting techniques.

Answer: Sorting is the process of arranging the elements of an array in either ascending or descending order. Some of the popular sorting techniques are:

• Bubble sort
• Insertion sort
• Selection sort

Question: Please explain the binary search. What is the best scenario for using a binary search?

Answer: The binary search is best applied to a list in which all the elements are already sorted. The binary search starts with searching in the middle of the list.

If the middle element is not the targeted element then it proceeds to search either the lower half or the upper half of the list. The process keeps on repeating until the desired element is found.

Question: How will you reference all elements in a one-dimensional array?

Answer: We need to use an indexed loop for referencing all elements in a one-dimension array. The counter starts from 0 to the number equal to 1 less than the array size. Hence, all elements are referenced in sequence by employing the loop counter as the array subscript.

Question: What do you understand by LIFO and FIFO?

Answer: LIFO and FIFO are two of the most popular forms of accessing, retrieving, and storing data. LIFO stands for Last In First Out. This means that in this approach the latest stored data is retrieved the first. This approach is followed in a stack.

FIFO stands for First In First Out and is the opposite approach of LIFO. Here, the data that is stored the oldest is the one to be retrieved first. FIFO approach is followed in a queue.

Question: Can you explain multi-dimensional array?

Answer: A conventional array has only one index. A multi-dimensional array is one that has multiple indexes. It is used where single-dimensional indexing is insufficient.

Question: Please explain a graph.

Answer: A type of data structure that has a set of ordered pairs is called a graph. These ordered pairs are also called arcs or edges. They are used for connecting nodes, which is where data is stored to and retrieved from.

Question: What is the difference between a linear and a non-linear data structure?

Answer: In a linear data structure, data elements are placed adjacent to each other. Arrays, linked lists, queues, and stacks are some examples of linear data structure.

In a non-linear data structure, it is possible for data elements to be connected to more than two data elements. Examples of the non-linear data structure are graphs and trees.

Question: Please explain an AVL tree.

Answer: A binary search tree that is always partially balanced is called an AVL tree. It is the first-ever data structure to be designed in such a way. The balance is the difference between the heights of the subtrees from the root.

Question: Why do we use Huffman’s algorithm?

Answer: For extending binary trees that have minimum weighted path length from given weights, we use Huffman’s algorithm. It uses a table containing the total number of times for each data element.

Question: Please explain Fibonacci search.

Answer: Fibonacci search is a type of search algorithm that applies to a sorted array. It uses the divide-and-conquer approach for greatly reducing the time required for reaching the target element.

Question: How does the recursive algorithm works?

Answer: The recursive algorithm divides a problem into smaller, easy-to-manage sub-problems. The output gained from one recursion after processing one sub-problem becomes input for the subsequent recursive process.

Question: What is a recursive function?

Answer: A function that calls itself is called a recursive function. It is based on a terminating condition and uses a stack. The phenomenon is called recursion.

Question: Please explain how does dynamic memory allocation help in managing data?

Answer: Dynamic memory allocation helps in storing simple structured data types. Moreover, it helps in combining separately allocated structure blocks for forming composite structures that can be expanded or contracted as required.

Question: What is the difference between NULL and VOID?

Answer: While NULL represents a value, VOID represents data type identifier. A variable with a NULL value represents an empty value. Pointers that have no initial size are identified using VOID.

Question: Please explain how variable declaration affects memory allocation.

Answer: A particular data type is defined with a variable declaration. The total amount of memory to be allocated depends on the data type a declared variable belongs to.

Question: Please explain data abstraction.

Answer: Data abstraction helps in breaking down a complex data problem into easily-manageable sub-problems. Following data abstraction, first data objects and operations to be performed on the same are specified. How the data objects will be stored in the memory becomes a secondary task.

Question: What the code to check a String is palindrome or not? 

Question: write a method that will remove any given character from a string.

Answer: 

Question: Print all permutation of String Recursive way?

Recursive way:

Question: Write a function to find out the longest palindrome in a given string?

Question: how to convert numeric string to int in java.

Result Output:

Question: Why String is final in Java?

Answer: There are two main reasons why string is final in Java to ensure the performance and security.  If strings are mutable then it can be easily attacked as strings are used in database URL and network connections. If strings are immutable then there are no synchronization issues as it will make the string thread-safe.

Question: How to remove duplicate elements from the array in Java?

Question: how to check if a tree is balanced or not in java , question: write a program to find all prime numbers up to a given number, question: write a program to find out if two rectangles r1 and r2 are overlapping, question: write a program for word-wrap which should work on any screen size, question: write a program to implement a blocking queue in java, question: how to check if two string are anagram, question: given two arrays, 1,2,3,4,5 and 2,3,1,0,5 find which number is not present in the second array, question: how to find the largest and smallest number in an array, question: how to find the top two maximum number in an array.

Wanna prepare more? This highly rated udemy course has helped thousands of interview candidates so must be useful to you as well: Break Away: Programming And Coding Interviews .

That completes our list of the programming interview questions that every aspiring programmer must know, and these questions will help you to crack the technical interviews. If you find some other problems at the time of the interview which are not listed here, please comment, and we will add those in the given list. All the best!

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With 5+ years of experience across various tech stacks such as C, C++, PHP, Python, SQL, Angular, and AWS, Vijay has a bachelor's degree in computer science and a specialty in SEO and helps a lot of ed-tech giants with their organic marketing. Also, he persists in gaining knowledge of content marketing and SEO tools. He has worked with various analytics tools for over eight years.

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• GitHub Copilot vs Amazon CodeWhisperer | Who's Best in 2024? Artificial Intelligence (AI) Code Editors IDEs AI Tools
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Top 16 Coding Interview Questions and Answers

Programming is an excellent profession with a strong job outlook, competitive compensation and a dynamic work environment where you’ll solve exciting problems. These factors can make programming positions highly competitive, so knowing what to expect from a programming interview is vital for any job seeker, and can make the difference between landing the role and being overlooked. This guide will discuss some of the most common coding interview questions asked in programming interviews so you’ll be more likely to ace your interview and start your career as a programmer.

Acing the interview is just one step on the path to becoming a coder. If you haven’t yet reached this stp in the process, or you’re not ready to apply for positions quite yet, our guide on how to become a coder can help you determine where to start.

How to prepare for a coding interview

Programming interviews can be tricky — they typically involve a mix of questions about your professional background and experience, as well as technical questions designed to gauge your programming knowledge and coding ability.

Practicing your responses to common coding interview questions can help you prepare for the interview, giving you the best possible chance of getting the job.

Knowing about the most in-demand programming languages is important for anyone wanting to enter the software development field. Having hands-on experience with a few of them — such as Java, Python, C# or JavaScript — is essential, however, the best options for you will depend on the types of applications you’ll be developing on the job. Review the requirements of the position as noted in the job description and make sure you can discuss the technical differences between each coding language listed.

Plan on providing an overview of your professional and educational background in the interview. Need a refresher? We have a guide to computer programmer education requirements to help you prepare to discuss how you learned to code and whether you’re self-taught, earned a degree in computer science or learned through a coding boot camp.

Programming interview questions

Programming interviews can feel intimidating, but preparing can give you a better understanding of the overall process and help you feel more confident during the interview. This section will discuss some general questions you can expect and provide strategies for answering them.

1. “Can you tell me a bit about your experience?”

This is one of the most fundamental questions you should expect to answer in any coding interview — and any interview at all, for that matter. The hiring manager will want to know about your experience and how well you can work in the company’s environment.

This question is relatively open-ended, and having a good answer can feel overwhelming. One common tactic is to answer in a “present, past, future” format. Start by talking about what you’re currently doing, how your past experience prepared you for the position and what you hope to be doing in the future. Mention any relevant projects, coding languages or other factors specific to the job you’re interviewing for.

One way to answer this question using the “present, past, future” format could be:

“At the moment I’m working as a programmer for a medium-sized software development company. This is my first programming position, and I got started by working on open-source projects and completing a coding boot camp. My eventual goal is to learn more about software development and become a software engineer.”

Did you know that if you don’t have as much experience in programming as you’d like, or don’t know the necessary coding languages, there are options available to help you gain the expertise you need in just six months or less? Completing a coding boot camp provides hands-on experience in some of the industry’s most valuable technologies, including HTML/CSS, JavaScript and React.js.

2. “Can you talk about some projects you’ve worked on?”

This question allows you to discuss previous experience regarding the projects you’ve worked on in the past. If you have professional coding knowledge, you can talk through the development life cycle of some of your best projects — the planning phase, how you contributed to the project’s execution and any post-completion maintenance you were involved in.

If you don’t have professional coding experience, but you’ve worked on impressive projects on your own, consider discussing your contributions in that context. Many programmers get started by contributing to open source projects, working for clients on a freelance basis or developing their own applications. Discussing these projects in detail can help you showcase your experience without previous job experience.

An example of how to answer this question could be: “I got started by doing simple bug fixes on open source projects. This helped me learn how to work on a project with a larger group of people. One project that I’m proud of is a personal to-do list that I coded using Java. It syncs tasks across multiple applications and is customized for my coding workflows.”

If you’re just getting started and need to build up your experience, our guide to the top ten coding projects for beginners can help you come up with some ideas.

3. “Can you talk about what programming languages you use? Talk about your experience with each language and which languages you prefer.”

Questions like this one are very likely to come up in most programming interviews. As this is an experience-related question that also focuses on your personal preferences, there is no “right” answer.

One way to answer this question is to focus on your favorite programming language and mention others that you are proficient in: “I enjoy using JavaScript because it is such a flexible language that powers so much of the modern web. While JavaScript is one of the first languages I learned in order to give my portfolio website more interactivity, I’m also familiar with Java, Python and HTML/CSS.”

4. “How do you stay current with your technical knowledge?”

Programming is a constantly evolving field that requires ongoing study. This question provides an opportunity to not only discuss your commitment to lifelong learning in the field, but also how you keep up with best practices, emerging technology and new programming languages. Talk about any websites, blogs, podcasts, video creators or social media influencers you follow in the space. This is also an opportunity to discuss any side projects or online courses you’ve worked on in order to improve your skills.

Possible answers to this question might look like: “For me, one of the best ways to stay current is to use newer technologies for projects. For example, I’ve been using Julia to understand a newer language that’s getting some interest from the development community. I also read trade press and blogs about software development to stay on top of how the field is changing over time.”

5. “How do you handle working with non-technical people from different backgrounds?”

While coding roles typically focus mostly on hard programming skills (i.e. technical knowledge of programming languages and how to create applications), soft skills are also essential for computer programmers. Often, programmers have to work with non-technical people from other departments to gain buy-in and understand the needs of the organization more clearly.

When answering this question, discuss the value of interdisciplinary cooperation within an organization. You might want to discuss how gaining a non-programmer’s perspective can help improve and innovate an application. Talk about how you communicate technical concepts to non-technical people and the importance of these soft skills in the workplace. For example: “I think it’s very important for technical and non-technical roles to work together. It can be easy for developers to get lost in the development process without looking to non-technical roles for feedback. Therefore, when meeting with those from non-technical backgrounds, I try to prepare a comprehensive guide or ‘cheat sheet’ offering key terminology, helpful acronyms and other important foundational information to help them review documentation more easily, which in turn can make the entire interaction easier to navigate.”

6. “How do you get started on a new coding project?”

Software development is more than just your code knowledge — knowing how to plan, structure and execute a project is also extremely important. This question gives you a great opportunity to use the STAR method. The STAR method is a technique used for behavioral and situational interview questions. Using the technique creates a straightforward story that the interviewer can follow with all relevant information included. This will involve the following:

Resolution:

Begin by discussing the context around the situation or challenge. Make sure this section is specific, short and to the point and provides enough background for the interviewer to understand. For the question above, that could look like this: “During my coding studies, I was given a complex design-related group project and a relatively short window of time to complete said project. I was faced with an opportunity to exercise high-level time management, team communication and coding efficiency to ensure the project was completed properly and on time.”

Next, discuss your responsibilities in the situation. Talk about the goal you needed to achieve or the task you were given. Again, this section does not need to be long, but should communicate the task at hand. For example, “I was tasked with quickly translating data set output into intuitive data visualizations.”

After discussing the task at hand, talk about how you handled the situation or the challenge. This section can be a bit longer and more in-depth, as the actions you took will tell the interviewer more about your thought process. “Given the quick turnaround time and the need for a flexible solution, I chose to employ Python — specifically, Pandas Visualization and Plotly — to complete the task.”

To wrap up the story, talk about how things ended. Did the project go well? Were there issues that needed to be solved? Take the opportunity to discuss any positive impacts or wins generated through the project. “As a result, the data visualization piece was well-received by the stakeholders and helped them quickly make data-driven decisions. In fact, they asked me to help implement my data visualization solution on another project that was in process at the same time.”

The STAR method can be used for a wide variety of situational questions and provides a framework for discussing the specifics of previous projects you’ve completed. Consider practicing how you’ll answer questions using the STAR method so you’re ready for whatever the interview brings.

If you’re looking for more experience and a way to brush up on your coding skills, completing a coding boot camp can help you answer interview questions like these or prepare you for other types of questions.

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Java interview questions

Programming interviews frequently involve specific coding questions and challenges designed to showcase your programming skills in a real-world setting. Answering these questions requires understanding the specific technical concepts that the hiring manager is looking for, such as strings, object-oriented programming (OOP) or code design principles. Preparing for these questions can feel daunting, but below are some common examples to help you prepare.

1. “Tell me about a project where you used Java. Why was Java your language of choice?”

This question tests your knowledge of Java in relation to other programming languages. Knowing the benefits of Java over other languages showcases your ability to work in a flexible way and use different technologies depending on the task at hand.

To answer this question, discuss a project you’ve worked on in the past and the reasons why Java was a good fit. For instance, you could say: “Java is a popular language for mobile development. For example, while working on a new application with a previous employer, our team decided to use Java to ensure mobile compatibility and cross-device functionality.”

2. “How do you reverse a string in Java?”

This is a common interview question asked when organizations use Java extensively. There is no specific utility for reversing in Java, so this problem will showcase your problem-solving skills and your domain knowledge of Java. These kinds of “puzzle” questions are very common in coding interviews, and the specifics of each question will change depending on how much experience is required for the position and the coding languages used at the organization.

Attempting these kinds of questions will help you prepare for coding interviews. If you have difficulties finding an answer, searching for threads on StackOverflow can help. StackOverflow is a website focused on helping developers find answers to their technical questions — finding different iterations of how to reverse a string can help you understand the process.

3. “What are Loops in Java? When would you use each type of loop?”

Loops are a key function in Java that allow a program to repeat a statement, or set of statements. A question like this is common for more junior-level developer positions and gives you the opportunity to demonstrate your knowledge of the three main types of loops in Java.

While Loops:

Do-while loops:.

For loops are used to repeatedly execute statements in a set way. These loops are used when the programmer knows how many times a set of instructions should be executed.

While loops are used to execute statements repeatedly until a condition is fulfilled. Before each execution, a condition is checked to see if the loop should continue running.

Do-while loops are similar to while loops, but the condition is checked after a statement or set of statements. As such, a do-while loop will run at least once, but a while loop might never loop if a condition is met before it can run.

4. “Which Java frameworks do you use and why?”

Java frameworks are an essential part of developing applications using the language. Frameworks are sets of pre-written code that can be used as a template for creating applications, allowing developers to program without writing the application entirely from scratch.

Your answer for this question depends entirely on your previous software development experience. If you are a more junior developer, you might not have used frameworks extensively in a professional capacity and that’s ok. One example of a popular Java framework that’s typically used to develop web applications is Spring .

Answering this question could look something like this: “Spring is my Java framework of choice. I enjoy using it because it’s lightweight, flexible and well-documented by the developer community. It took me some time to become familiar with the framework, but I’m confident the effort was worth it.”

5. “Code an application that does ‘x’.”

Many programming interviews involve actually writing code during the interview, either on a whiteboard or on a computer. There are many varieties of this question where the interviewer presents a problem or a set of functionalities that you’ll have to create on the fly. These can be a source of stress for many programmers, but it’s possible to prepare for these types of questions.

These coding task questions are varied, but some examples are seen more frequently than others. One such example is “FizzBuzz.” The FizzBuzz problem is typically a variation of the following: Write a Java program that prints out the numbers 1 to 50 but, for multiples of three, print the word “Fizz” and for multiples of five, print the word “Buzz.” For numbers that are multiples of both three and five, print the word “FizzBuzz.”

FizzBuzz is a classic programming question that’s focused on weeding out programmers who can’t actually code. The question is relatively basic, but interviewees without programming knowledge might not be able to write a program that can complete the task.

There are many possible programming problems that might be asked during the course of a programming interview. Whatever type of question you face, be sure to take the time to discuss your methodology as you work through a solution. Being able to come up with a solution and work through your thought process are both valuable skills for programmers.

Python interview questions

Python is a popular programming language used across a wide range of fields and applications. Many programming positions will require some knowledge of Python, so having a basic understanding of the language is vital for anyone looking to do well in an interview. This section will cover some possible questions to help you prepare.

If you don’t have prior experience and want to know more, check out our guide on learning Python . This guide covers why you should learn Python, the basics of the language and how to learn more.

1. “What is Python and what are the benefits of using it?”

Questions like this one can be used to showcase your level of knowledge and skill with a programming language and your understanding of situations where this language’s use is optimal.

Being prepared for this question can help you ace your programming interview. Python is one of the most easily accessible languages due to its use of “natural language” syntax, making it great for beginners and relatively easy for more experienced programmers to pick up. In addition, it can be used for a wide range of applications across many industries.

Some of Python’s benefits that you can incorporate into your answer include

Ease of use and debugging due to natural language syntax

Open source language status

Extensive library support

Robust developer and online community support

2. “What do you dislike about Python?”

This is an interesting question that can come up during the interview process. Knowing how to answer it requires a deep understanding of Python, its strengths and its weaknesses. It’s easier to research Python’s benefits and positive attributes without actually having a lot of experience in the language — knowing what you dislike about the language takes more experience.

A few drawbacks of Python include the following

Limited mobile application support

Interpreted nature can impact speed

Less memory-efficient than other languages

Answering this question could sound something like this: “Python is great for many applications, but there are always drawbacks to consider with any language. For example, Python is interpreted, which makes it easier to learn and use, but that aspect can impact efficiency. It might not be the best choice for an application where efficiency is the most important factor. Python’s limited mobile development support is another reason that can keep me from using it in some projects.”

3. “What are some of the most common mistakes that programmers make when using Python?”

This question gives interviewers the chance to see how a candidate stays organized and accurate when building software. Knowing how to avoid common mistakes is vital for any developer. Those mistakes include using tabs instead of spaces and using generic, non-unique identifiers. Another is neglecting to run regular code analyses — this can introduce typos or missing definitions for variables. Incorporate ways to avoid these mistakes into your answer to set yourself up for success.

4. “How do you identify bugs and issues in your code?”

Code is rarely, if ever, completely error-free, and knowing how to troubleshoot issues is a crucial skill for any programmer. Discuss any analysis tools you utilize, like PyChecker or Pylint , as well as any methodologies or strategies you use for debugging throughout your coding process. Answering this question could involve saying, “PyChecker is my debugging tool of choice. Writing clean, bug-free code is so important for developers, especially developers working on a team with others. Identifying and fixing bugs is an important part of my development process.”

As we discussed in the Java section, you might have to use Python to code an example application using a prompt from the interviewer. When preparing for these types of questions, consider taking Python practice tests and working through your solutions out loud. The ability to describe your thought process as you code is crucial for these code-based questions.

Ready to ace your coding interview?

Programming is a great career, but getting started can be difficult without previous coding experience. If you’re looking for ways to build up your coding skills and ace programming interviews, enrolling in Berkeley Coding Boot Camp is a great place to start. You’ll learn in-demand coding skills from seasoned professionals while gaining hands-on experience working though real-world projects to populate your professional portfolio. Take the next step and enroll to start your programming career journey today!

• Python Basics
• Interview Questions
• Python Quiz
• Popular Packages

Python Projects

• Practice Python
• AI With Python
• Learn Python3
• Python Automation
• Python Web Dev
• DSA with Python
• Python OOPs
• Dictionaries

Python Exercise with Practice Questions and Solutions

• Python List Exercise
• Python String Exercise
• Python Tuple Exercise
• Python Dictionary Exercise
• Python Set Exercise

Python Matrix Exercises

• Python program to a Sort Matrix by index-value equality count
• Python Program to Reverse Every Kth row in a Matrix
• Python Program to Convert String Matrix Representation to Matrix
• Python - Count the frequency of matrix row length
• Python - Convert Integer Matrix to String Matrix
• Python Program to Convert Tuple Matrix to Tuple List
• Python - Group Elements in Matrix
• Python - Assigning Subsequent Rows to Matrix first row elements
• Adding and Subtracting Matrices in Python
• Python - Convert Matrix to dictionary
• Python - Convert Matrix to Custom Tuple Matrix
• Python - Matrix Row subset
• Python - Group similar elements into Matrix
• Python - Row-wise element Addition in Tuple Matrix
• Create an n x n square matrix, where all the sub-matrix have the sum of opposite corner elements as even

Python Functions Exercises

• Python splitfields() Method
• How to get list of parameters name from a function in Python?
• How to Print Multiple Arguments in Python?
• Python program to find the power of a number using recursion
• Sorting objects of user defined class in Python
• Assign Function to a Variable in Python
• Returning a function from a function - Python
• What are the allowed characters in Python function names?
• Defining a Python function at runtime
• Explicitly define datatype in a Python function
• Functions that accept variable length key value pair as arguments
• How to find the number of arguments in a Python function?
• How to check if a Python variable exists?
• Python - Get Function Signature
• Python program to convert any base to decimal by using int() method

Python Lambda Exercises

• Python - Lambda Function to Check if value is in a List
• Difference between Normal def defined function and Lambda
• Python: Iterating With Python Lambda
• How to use if, else & elif in Python Lambda Functions
• Python - Lambda function to find the smaller value between two elements
• Lambda with if but without else in Python
• Python Lambda with underscore as an argument
• Difference between List comprehension and Lambda in Python
• Nested Lambda Function in Python
• Python lambda
• Python | Sorting string using order defined by another string
• Python | Find fibonacci series upto n using lambda
• Overuse of lambda expressions in Python
• Python program to count Even and Odd numbers in a List
• Intersection of two arrays in Python ( Lambda expression and filter function )

Python Pattern printing Exercises

• Simple Diamond Pattern in Python
• Python - Print Heart Pattern
• Python program to display half diamond pattern of numbers with star border
• Python program to print Pascal's Triangle
• Python program to print the Inverted heart pattern
• Python Program to print hollow half diamond hash pattern
• Program to Print K using Alphabets
• Program to print half Diamond star pattern
• Program to print window pattern
• Python Program to print a number diamond of any given size N in Rangoli Style
• Python program to right rotate n-numbers by 1
• Python Program to print digit pattern
• Print with your own font using Python !!
• Python | Print an Inverted Star Pattern
• Program to print the diamond shape

Python DateTime Exercises

• Python - Iterating through a range of dates
• How to add time onto a DateTime object in Python
• How to add timestamp to excel file in Python
• Convert string to datetime in Python with timezone
• Isoformat to datetime - Python
• Python datetime to integer timestamp
• How to convert a Python datetime.datetime to excel serial date number
• How to create filename containing date or time in Python
• Convert "unknown format" strings to datetime objects in Python
• Extract time from datetime in Python
• Convert Python datetime to epoch
• Python program to convert unix timestamp string to readable date
• Python - Group dates in K ranges
• Python - Divide date range to N equal duration
• Python - Last business day of every month in year

Python OOPS Exercises

• Get index in the list of objects by attribute in Python
• Python program to build flashcard using class in Python
• How to count number of instances of a class in Python?
• Shuffle a deck of card with OOPS in Python
• What is a clean and Pythonic way to have multiple constructors in Python?
• How to Change a Dictionary Into a Class?
• How to create an empty class in Python?
• Student management system in Python
• How to create a list of object in Python class

Python Regex Exercises

• Validate an IP address using Python without using RegEx
• Python program to find the type of IP Address using Regex
• Converting a 10 digit phone number to US format using Regex in Python
• Python program to find Indices of Overlapping Substrings
• Python program to extract Strings between HTML Tags
• Python - Check if String Contain Only Defined Characters using Regex
• How to extract date from Excel file using Pandas?
• Python program to find files having a particular extension using RegEx
• How to check if a string starts with a substring using regex in Python?
• How to Remove repetitive characters from words of the given Pandas DataFrame using Regex?
• Extract punctuation from the specified column of Dataframe using Regex
• Extract IP address from file using Python
• Python program to Count Uppercase, Lowercase, special character and numeric values using Regex
• Categorize Password as Strong or Weak using Regex in Python
• Python - Substituting patterns in text using regex

Python LinkedList Exercises

• Python program to Search an Element in a Circular Linked List
• Implementation of XOR Linked List in Python
• Pretty print Linked List in Python
• Python Library for Linked List
• Python | Stack using Doubly Linked List
• Python | Queue using Doubly Linked List
• Program to reverse a linked list using Stack
• Python program to find middle of a linked list using one traversal
• Python Program to Reverse a linked list

Python Searching Exercises

• Binary Search (bisect) in Python
• Python Program for Linear Search
• Python Program for Anagram Substring Search (Or Search for all permutations)
• Python Program for Binary Search (Recursive and Iterative)
• Python Program for Rabin-Karp Algorithm for Pattern Searching
• Python Program for KMP Algorithm for Pattern Searching

Python Sorting Exercises

• Python Code for time Complexity plot of Heap Sort
• Python Program for Stooge Sort
• Python Program for Recursive Insertion Sort
• Python Program for Cycle Sort
• Bisect Algorithm Functions in Python
• Python Program for BogoSort or Permutation Sort
• Python Program for Odd-Even Sort / Brick Sort
• Python Program for Gnome Sort
• Python Program for Cocktail Sort
• Python Program for Bitonic Sort
• Python Program for Pigeonhole Sort
• Python Program for Comb Sort
• Python Program for Iterative Merge Sort
• Python Program for Binary Insertion Sort
• Python Program for ShellSort

Python DSA Exercises

• Saving a Networkx graph in GEXF format and visualize using Gephi
• Dumping queue into list or array in Python
• Python program to reverse a stack
• Python - Stack and StackSwitcher in GTK+ 3
• Multithreaded Priority Queue in Python
• Python Program to Reverse the Content of a File using Stack
• Priority Queue using Queue and Heapdict module in Python
• Box Blur Algorithm - With Python implementation
• Python program to reverse the content of a file and store it in another file
• Check whether the given string is Palindrome using Stack
• Take input from user and store in .txt file in Python
• Change case of all characters in a .txt file using Python
• Finding Duplicate Files with Python

Python File Handling Exercises

• Python Program to Count Words in Text File
• Python Program to Delete Specific Line from File
• Python Program to Replace Specific Line in File
• Python Program to Print Lines Containing Given String in File
• Python - Loop through files of certain extensions
• Compare two Files line by line in Python
• How to keep old content when Writing to Files in Python?
• How to get size of folder using Python?
• How to read multiple text files from folder in Python?
• Read a CSV into list of lists in Python
• Python - Write dictionary of list to CSV
• Convert nested JSON to CSV in Python
• How to add timestamp to CSV file in Python

Python CSV Exercises

• How to create multiple CSV files from existing CSV file using Pandas ?
• How to read all CSV files in a folder in Pandas?
• How to Sort CSV by multiple columns in Python ?
• Working with large CSV files in Python
• How to convert CSV File to PDF File using Python?
• Visualize data from CSV file in Python
• Python - Read CSV Columns Into List
• Sorting a CSV object by dates in Python
• Python program to extract a single value from JSON response
• Convert class object to JSON in Python
• Convert multiple JSON files to CSV Python
• Convert JSON data Into a Custom Python Object
• Convert CSV to JSON using Python

Python JSON Exercises

• Flattening JSON objects in Python
• Saving Text, JSON, and CSV to a File in Python
• Convert Text file to JSON in Python
• Convert JSON to CSV in Python
• Convert JSON to dictionary in Python
• Python Program to Get the File Name From the File Path
• How to get file creation and modification date or time in Python?
• Menu driven Python program to execute Linux commands
• Menu Driven Python program for opening the required software Application
• Open computer drives like C, D or E using Python

Python OS Module Exercises

• Rename a folder of images using Tkinter
• Kill a Process by name using Python
• Finding the largest file in a directory using Python
• Python - Get list of running processes
• Python - Get file id of windows file
• Python - Get number of characters, words, spaces and lines in a file
• Change current working directory with Python
• How to move Files and Directories in Python
• How to get a new API response in a Tkinter textbox?
• Build GUI Application for Guess Indian State using Tkinter Python
• How to stop copy, paste, and backspace in text widget in tkinter?
• How to temporarily remove a Tkinter widget without using just .place?
• How to open a website in a Tkinter window?

Python Tkinter Exercises

• Create Address Book in Python - Using Tkinter
• Changing the colour of Tkinter Menu Bar
• How to check which Button was clicked in Tkinter ?
• How to add a border color to a button in Tkinter?
• How to Change Tkinter LableFrame Border Color?
• Looping through buttons in Tkinter
• Visualizing Quick Sort using Tkinter in Python
• How to Add padding to a tkinter widget only on one side ?
• Python NumPy - Practice Exercises, Questions, and Solutions
• Pandas Exercises and Programs
• How to get the Daily News using Python
• How to Build Web scraping bot in Python
• Scrape LinkedIn Using Selenium And Beautiful Soup in Python
• Scraping Reddit with Python and BeautifulSoup
• Scraping Indeed Job Data Using Python

Python Web Scraping Exercises

• How to Scrape all PDF files in a Website?
• How to Scrape Multiple Pages of a Website Using Python?
• Quote Guessing Game using Web Scraping in Python
• How to extract youtube data in Python?
• How to Download All Images from a Web Page in Python?
• Test the given page is found or not on the server Using Python
• How to Extract Wikipedia Data in Python?
• How to extract paragraph from a website and save it as a text file?
• Automate Youtube with Python
• Controlling the Web Browser with Python
• How to Build a Simple Auto-Login Bot with Python
• Download Google Image Using Python and Selenium
• How To Automate Google Chrome Using Foxtrot and Python

Python Selenium Exercises

• How to scroll down followers popup in Instagram ?
• How to switch to new window in Selenium for Python?
• Python Selenium - Find element by text
• How to scrape multiple pages using Selenium in Python?
• Python Selenium - Find Button by text
• Web Scraping Tables with Selenium and Python
• Selenium - Search for text on page
• Python Projects - Beginner to Advanced

Python Exercise: Practice makes you perfect in everything. This proverb always proves itself correct. Just like this, if you are a Python learner, then regular practice of Python exercises makes you more confident and sharpens your skills. So, to test your skills, go through these Python exercises with solutions.

Python is a widely used general-purpose high-level language that can be used for many purposes like creating GUI, web Scraping, web development, etc. You might have seen various Python tutorials that explain the concepts in detail but that might not be enough to get hold of this language. The best way to learn is by practising it more and more.

The best thing about this Python practice exercise is that it helps you learn Python using sets of detailed programming questions from basic to advanced. It covers questions on core Python concepts as well as applications of Python in various domains. So if you are at any stage like beginner, intermediate or advanced this Python practice set will help you to boost your programming skills in Python.

List of Python Programming Exercises

In the below section, we have gathered chapter-wise Python exercises with solutions. So, scroll down to the relevant topics and try to solve the Python program practice set.

Python List Exercises

• Python program to interchange first and last elements in a list
• Python program to swap two elements in a list
• Python | Ways to find length of list
• Maximum of two numbers in Python
• Minimum of two numbers in Python

>> More Programs on List

Python String Exercises

• Python program to check whether the string is Symmetrical or Palindrome
• Reverse words in a given String in Python
• Ways to remove i’th character from string in Python
• Find length of a string in python (4 ways)
• Python program to print even length words in a string

>> More Programs on String

Python Tuple Exercises

• Python program to Find the size of a Tuple
• Python – Maximum and Minimum K elements in Tuple
• Python – Sum of tuple elements
• Python – Row-wise element Addition in Tuple Matrix
• Create a list of tuples from given list having number and its cube in each tuple

>> More Programs on Tuple

Python Dictionary Exercises

• Python | Sort Python Dictionaries by Key or Value
• Handling missing keys in Python dictionaries
• Python dictionary with keys having multiple inputs
• Python program to find the sum of all items in a dictionary
• Python program to find the size of a Dictionary

>> More Programs on Dictionary

Python Set Exercises

• Find the size of a Set in Python
• Iterate over a set in Python
• Python – Maximum and Minimum in a Set
• Python – Remove items from Set
• Python – Check if two lists have atleast one element common

>> More Programs on Sets

• Python – Assigning Subsequent Rows to Matrix first row elements
• Python – Group similar elements into Matrix

>> More Programs on Matrices

>> More Programs on Functions

• Python | Find the Number Occurring Odd Number of Times using Lambda expression and reduce function

>> More Programs on Lambda

• Programs for printing pyramid patterns in Python

>> More Programs on Python Pattern Printing

• Python program to get Current Time
• Get Yesterday’s date using Python
• Python program to print current year, month and day
• Python – Convert day number to date in particular year
• Get Current Time in different Timezone using Python

>> More Programs on DateTime

>> More Programs on Python OOPS

• Python – Check if String Contain Only Defined Characters using Regex

>> More Programs on Python Regex

>> More Programs on Linked Lists

>> More Programs on Python Searching

• Python Program for Bubble Sort
• Python Program for QuickSort
• Python Program for Insertion Sort
• Python Program for Selection Sort
• Python Program for Heap Sort

>> More Programs on Python Sorting

• Program to Calculate the Edge Cover of a Graph
• Python Program for N Queen Problem

>> More Programs on Python DSA

• Read content from one file and write it into another file
• Write a dictionary to a file in Python
• How to check file size in Python?
• Find the most repeated word in a text file
• How to read specific lines from a File in Python?

>> More Programs on Python File Handling

• Update column value of CSV in Python
• How to add a header to a CSV file in Python?
• Get column names from CSV using Python
• Writing data from a Python List to CSV row-wise

>> More Programs on Python CSV

>> More Programs on Python JSON

• Python Script to change name of a file to its timestamp

>> More Programs on OS Module

• Python | Create a GUI Marksheet using Tkinter
• Python | ToDo GUI Application using Tkinter
• Python | GUI Calendar using Tkinter
• File Explorer in Python using Tkinter
• Visiting Card Scanner GUI Application using Python

>> More Programs on Python Tkinter

NumPy Exercises

• How to create an empty and a full NumPy array?
• Create a Numpy array filled with all zeros
• Create a Numpy array filled with all ones
• Replace NumPy array elements that doesn’t satisfy the given condition
• Get the maximum value from given matrix

>> More Programs on NumPy

Pandas Exercises

• Make a Pandas DataFrame with two-dimensional list | Python
• How to iterate over rows in Pandas Dataframe
• Create a pandas column using for loop
• Create a Pandas Series from array
• Pandas | Basic of Time Series Manipulation

>> More Programs on Python Pandas

>> More Programs on Web Scraping

• Download File in Selenium Using Python
• Bulk Posting on Facebook Pages using Selenium
• Google Maps Selenium automation using Python
• Count total number of Links In Webpage Using Selenium In Python
• Extract Data From JustDial using Selenium

>> More Programs on Python Selenium

• Number guessing game in Python
• 2048 Game in Python
• Get Live Weather Desktop Notifications Using Python
• 8-bit game using pygame
• Tic Tac Toe GUI In Python using PyGame

>> More Projects in Python

In closing, we just want to say that the practice or solving Python problems always helps to clear your core concepts and programming logic. Hence, we have designed this Python exercises after deep research so that one can easily enhance their skills and logic abilities.

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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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Table of Contents

Coding interview questions on conceptual understanding, programming interview questions, choose the right software development program, get ahead of the curve and master programming today, top 40 coding interview questions you should know.

Programming questions are an integral part of an interview for the developer's position. No matter which programming language you master, familiarity with fundamental concepts of programming is something that is always expected from you.

Coding skills are always the deciding factor in any programming interview. In this coding interview questions article, we will discuss the top 40 Coding Interview Questions you should absolutely know to crack those interviews and get your dream job.

So without further ado, let’s get started!

Watch the video below that deals with real-time and corporate-level programming-based interview questions and answers.

The coding interview questions addresses in this article are grouped into 2 categories (as below) to make your learning simpler.

• Conceptual Interview Questions

We will now look at the first category of coding interview questions. 

This section covers some coding interview questions that test the conceptual understanding of the candidate.

1. What is a Data Structure?

• A data structure is a storage format that defines the way data is stored, organized, and manipulated.
• Some popular data structures are Arrays, Trees, and Graphs.

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2. What is an Array?

• An array is commonly referred to as a collection of items stored at contiguous memory locations.
• Items stored are of the same type.
• It organizes data so that a related set of values can be easily sorted or searched.

3. What is a Linked List?

• Like an array, a linked list refers to a linear data structure in which the elements are not necessarily stored in a contiguous manner.
• It is basically a sequence of nodes, each node points towards the next node forming a chain-like structure.

Fig: Linked List

4. What is LIFO?

• LIFO is an abbreviation for Last In First Out
• It is a way of accessing, storing and retrieving data.
• It extracts the data that was stored last first.

5. What is a Stack?

• A stack refers to a linear data structure performing operations in a LIFO (Last In First Out) order.
• In a stack, elements can only be accessed, starting from the topmost to the bottom element.

6. What is FIFO?

• FIFO stands for First In First Out.
• The data that was stored first is extracted first.

Fig: LIFO, FIFO

Till now, you’ve covered some very fundamental coding interview questions. Going ahead you will dive deeper into the subject.

7. What is a Queue?

• A queue refers to a linear data structure that performs operations in a FIFO order.
• In a queue, the least recently added elements are removed first as opposed to a stack. 

8. What are Binary Trees?

• A binary tree is an extension of the linked list structure where each node has at most two children. 
• A binary tree has two nodes at all times, a left node and a right node.

Fig: Binary Trees

9. What is Recursion?

• Recursion refers to a function calling itself based on a terminating condition.
• It uses LIFO and therefore makes use of the stack data structure.

The next couple of coding interview questions will explore your knowledge of OOPs.

10. What is the OOPs concept?

OOPs stands for Object-Oriented Programming System, a paradigm that provides concepts such as objects, classes, and inheritance.

11. What are the concepts introduced in OOPs?

Following are the concepts introduced in OOPs:

• Object - A real-world entity having a particular state and behavior. We can define it as an instance of a class.
• Class - A logical entity that defines the blueprint from which an object can be created or instantiated.
• Inheritance - A concept that refers to an object gaining all the properties and behaviors of a parent object. It provides code reusability.
• Polymorphism - A concept that allows a task to be performed in different ways. In Java, we use method overloading and method overriding to achieve polymorphism.
• Abstraction - A concept that hides the internal details of an application and only shows the functionality. In Java, we use abstract class and interface to achieve abstraction.
• Encapsulation - A concept that refers to the wrapping of code and data together into a single unit.

This is one of the very common coding interview questions, that often allows the interviewer to branch out into related topics based on the candidate’s answers

12. Explain what a Binary Search Tree is.

• A binary search tree is used to store data in a manner that it can be retrieved very efficiently. 
• The left sub-tree contains nodes whose keys are less than the node’s key value.
• The right sub-tree contains nodes whose keys are greater than or equal to the node’s key value

Fig: Binary Search Tree

13. Explain Doubly Linked Lists?

• Doubly linked lists are categorized as a special type of linked list in which traversal across the data elements can be done in both directions. 
• This is made possible by the presence of two links in every node, one that links to the node next to it and another that connects to the node before it.

Fig: Doubly Linked List

14. What is a Graph?

• A graph is a particular type of data structure that contains a set of ordered pairs.
• The ordered pairs in a graph are also known as edges or arcs and are most commonly used to connect nodes where the data can be stored and retrieved.

15. Differentiate between linear and non-linear data structure?

16. what is a deque.

• A deque is a double-ended queue.
• This is a structure in which elements can be inserted or removed from either end.

17. What’s the difference between Stack and Array ?

18. which sorting algorithm is the best.

• There are many types of sorting algorithms: bubble sort, quick sort, balloon sort, merge sort, radix sort, and more.
• No algorithm can be considered as the best or fastest because they have designed each for a specific type of data structure where it performs the best

19. How does variable declaration affect memory?

• The amount of memory that is to be reserved or allocated depends on the data type being stored in that variable. 
• For example, if a variable is declared to be “integer type”, 32 bits of memory storage will then be reserved for that particular variable.

20. What are dynamic data structures?

Dynamic data structures have the feature where they expand and contract as a program runs. It provides a very flexible method of data manipulation because adjusts based on the size of the data to be manipulated.

These 20 coding interview questions that test the conceptual understanding of the candidates give the interview a clear idea on how strong the candidate’s fundamentals are

The next set of coding interview questions focus tests the programming expertise of the candidates and dives deep into various related aspects.

The code screenshots given along with the below coding interview questions helps you provide the answer to the question, with clarity.

21. How do you reverse a string in Java?

• Declare a string.
• Take out the length of that string.
• Loop through the characters of the string.
• Add the characters in reverse order in the new string.

22. How do you determine if a string is a palindrome?

• A string is a palindrome when it stays the same on reversing the order of characters in that string.
• It can be achieved by reversing the original string first and then checking if the reversed string is equal to the original string.

23. Find the number of occurrences of a character in a String?

To find the number of occurrences, loop through the string and search for that character at every iteration; whenever it is found, it will update the count.

24. How to find out if the given two strings are anagrams or not?

Two strings are anagrams if they contain a similar group of characters in a varied sequence.

• Declare a boolean variable that tells at the end of the two strings are anagrams or not.
• First, check if the length of both strings is the same, if not, they cannot be anagrams.
• Convert both the strings to character arrays and then sort them.
• Check if the sorted arrays are equal. If they are equal, print anagrams, otherwise not anagrams. 

boolean anagrmstat = false;

if (str.length() != reverse.length()) {

    System.out.println(str + " and " + reverse + " not anagrams string");

    char[] anagram1 = str.toCharArray();

    char[] anagram2 = reverse.toCharArray();

    Arrays.sort(anagram1);

    Arrays.sort(anagram2);

    anagrmstat = Arrays.equals(anagram1, anagram2);

if (anagrmstat == true) {

    System.out.println(" anagrams string");

    System.out.println(" not anagrams string");

25. How do you calculate the number of vowels and consonants in a String?

• Loop through the string.
• Increase the vowel variable by one whenever the character is found to be a vowel, using the if condition. Otherwise, increment the consonant variable.
• Print the values of both the vowel and the consonant count.

int vowels = 0;

int consonants = 0;

for (int k = 0; k < str.length(); k++) {

    char c = str.charAt(k);

    if (c == 'a' || c == 'e' || c == 'i' || c == 'o' || c == 'u')

        vowels++;

        consonants++;

System.out.println("Vowel count is " + vowels);

System.out.println("Consonant count is: " + consonants);

26. How do you get the matching elements in an integer array?

• Declare an array.
• Nest a couple of loops to compare the numbers with other numbers in the array.
• Print the matching elements if found.

int[] a = { 1, 2, 3, 4, 5, 1, 2, 6, 7 };

for (int m = 0; m < a.length; m++) {

    for (int n = m + 1; n < a.length; n++) {

        if (a[m] == a[n])

            System.out.print(a[m]);

27. How would you implement the bubble sort algorithm?

• Nest a couple of loops to compare the numbers in the array.
• The array will be sorted in ascending order by replacing the elements if found in any other order.

int[] a = { 1, 2, 7, 6, 4, 9, 12 };

for (int k = 0; k < a.length; k++) {

    for (int l = 0; l < a.length - l - 1; l++) {

        if (a[l] > a[l + 1]) {

            int t = a[l];

            a[l] = a[l + 1];

            a[l + 1] = t;

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28. How would you implement the insertion sort algorithm?

• We assume the first element in the array to be sorted. The second element is stored separately in the key. This sorts the first two elements. You can then take the third element and do a comparison with the ones on the left of it. This process will go on until a point where we sort the array.

for (int m = 1; m < a.length; m++) {

    int n = m;

    while (n > 0 && a[n - 1] > a[n]) {

        int k = a[n];

        a[n] = a[n - 1];

        a[n - 1] = k;

        n--;

29. How do you reverse an array?

• Loop till the half-length of the array.
• Replace the numbers corresponding to the indexes from the starting and the end.

for (int t = 0; t < a.length / 2; t++) { 

    int tmp = a[t]; 

    a[t] = a[a.length - t - 1]; 

    a[a.length - t- 1] = tmp; 

30. How would you swap two numbers without using a third variable?

• Declare two variables and initialize them with values.
• Make b the sum of both numbers.
• Then subtract the sum (b) from a, so a is now swapped.
• Lastly, subtract a from the sum (b), so b is also swapped.

int a = 10;

int b = 20;

b = b + a; // now b is sum of both the numbers

a = b - a; // b - a = (b + a) - a = b (a is swapped)

b = b - a; // (b + a) - b = a (b is swapped)

31. Print a Fibonacci series using recursion?

• The Fibonacci numbers are the numbers in the following integer sequence:

0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, ……..

• We can calculate them using the mathematical formula used in the Fibonacci recursive function.

public static int fibonacci(int n) {

    if (n <= 1)

        return n;

    return fibonacci(n - 1) + fibonacci(n - 2);

public static void main(String args[]) {

    int n = 10;

    System.out.println(fibonacci(n));

32. How do you find the factorial of an integer?

• A factorial is a function that multiplies a number by every number below it. For example, 5!= 5*4*3*2*1=120.
• Recursive function multiples the numbers until it reaches 1.

public static long factorial(long n) {

if (n == 1)

    return 1;

    return (n * factorial(n - 1));

33. How do you reverse a Linked List?

• Declare a linked list.
• Add elements to that linked list.
• Apply the descending iterator method to the linked list.
• This reverses the order of elements in the linked list.

LinkedList<Integer> ll = new LinkedList<>();

System.out.println(ll);

LinkedList<Integer> ll1 = new LinkedList<>();

ll.descendingIterator().forEachRemaining(ll1::add);

System.out.println(ll1);

34. How would you implement Binary Search?

• Binary search divides the array into half in every iteration step until it finds the element.
• It works on the sorted arrays since it compares the values of adjacent elements and then calculates the mid number.
• If the value of low becomes greater than high at any point, it means the element is not present in the list.

int mid = (low + high) / 2;

while (low <= high) {

    if (arr[mid] < key) {

        low = mid + 1;

    } else if (arr[mid] == key) {

        return mid;

    } else {

        high = mid - 1;

    mid = (low + high) / 2;

if (low > high) {

    return -1;

35. How would you find the second largest number in an array?

• Loop through the array.
• If the value of i is greater than the highest, store the value of i in highest, and store the value of highest in the second-highest variable.

private static int findSecondHighest(int[] array) {

    int highest = Integer.MIN_VALUE;

    int secondHighest = Integer.MIN_VALUE;

    for (int i : array) {

        if (i > highest) {

            secondHighest = highest;

            highest = i;

        } else if (i > secondHighest) {

            secondHighest = i;

    return secondHighest;

36. How do you remove all occurrences of a given character from the input string?

• Use the built-in string method “replace” to replace a character with any other character, including symbols and white spaces.

String str1 = "Australia";

str1 = str1.replace("a", "");

System.out.println(str1); // ustrli

37. Showcase Inheritance with the help of a program?

• The class Cat inherits the property color from the class Animal by extending the parent class (Animal).
• This way a class Cat can have more parent classes if it wishes to inherit their properties.

class Animal {

    String color;

class Cat extends Animal {

    void meow() {

        System.out.println("Meow");

38. Explain overloading and overriding with the help of a program?

Overloading:

When a class has two or more methods with the same name, they are called overloaded methods.

class Foo {

    void print(String s) {

        System.out.println(s);

    void print(String s, int count) {

        while (count > 0) {

            System.out.println(s);

            count--;

Overriding:

When a superclass method is also implemented in the child class, it’s a case of overriding.

class Base {

    void printName() {

        System.out.println("Base Class");

class Child extends Base {

    @Override

        System.out.println("Child Class");

39. How do you check if the given number is prime?

• Use if statements to check for each condition separately:
• If the number is 0 or 1, it cannot be prime.
• If the number is 2, it is prime number.
• If the number is indivisible by other numbers, it is prime.

public static boolean isPrime(int n) {

    if (n == 0 || n == 1) {

        return false;

    if (n == 2) {

        return true;

    for (int i = 2; i <= n / 2; i++) {

        if (n % i == 0) {

            return false;

    return true;

40. How do you sum all the elements in an array?

• Use for loop to iterate through the array and keep adding the elements in that array.

int[] array = { 1, 2, 3, 4, 5 };

int sum = 0;

for (int i : array)

    sum += i;

System.out.println(sum);

As you get prepared for your job interview, we hope that these Coding Interview Questions have provided more insight into what types of questions you are likely to come across.

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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.

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