Top 12 Coding Interview FAQ: Preparation Guide

Nowadays, it has become essential to crack the coding interviews to get a job as a software developer in any tech company. There are a total of 26.9 million active software developers in the world, and this number is expected to grow to 45 million by 2030. The growing number of software developers highlights the value of the software development profession and increasing competition in the industry. So, companies are evolving their interview process to hire the most skilled candidates.

Whether you are a fresh graduate or a professional software developer, you need to crack the coding interviews to join tech companies. The best way to crack the coding interview is to prepare yourself before you sit in the interview. So, I’ve covered the most commonly asked coding interview questions by software developers in this guide. These questions will help you to understand what a coding interview is, how you should prepare for a coding interview, how you get evaluated in the coding interview, etc.

However, this guide doesn’t cover technical coding interview questions. If you have basic knowledge about coding interviews and how to prepare for them, you can explore Grokking coding interview patterns course to practice technical coding questions.

Look at the below coding interview FAQs. I’ve answered them in depth.

1. What is a coding interview?

Whenever you apply for a software developer job role in any company, you need to go through the technical interview process to join the company. The technical interview can have multiple rounds, like coding interview rounds, system design interview rounds, etc. Some large tech companies like FAANG (Facebook, Apple, Amazon, Netflix, Google) conduct 2 coding interview rounds.

The purpose of the coding interview is to evaluate your knowledge of data structure, algorithms, and other core concepts of computer science and programming. So, interviewers give you technical coding questions, which you need to solve and write the code in a real-time collaborative environment. The complexity of the given problems can be different according to the position you are applying for and your experience. You might be required to solve multiple coding questions during the coding interview.

Many companies have a similar coding interview process, but it’s not exactly the same. So, you should research the coding interview process of a particular company before you present for the interview.

2. What concepts are discussed during the coding interview?

The discussion of the concepts during the coding interviews totally depends on the interviewer and the job role you are applying for.

Typically, data structures and algorithms are discussed in the coding interview. Sometimes, interviewers also discuss object-oriented programming and system design related concepts.

Let’s explore the mainly discussed concepts in the coding interview.

• Data Structure: The interviewer can give you the coding problem related to a single or multi-dimensional array, strings, linked list, etc. Furthermore, you will also be asked about advanced data structures like trees, graphs, trie, stack, queues, hashtable, etc. So, you need to be prepared with them. Sometimes, the interviewer also asks fundamental questions about data structure. For example, how stack and queue are different, explain array indexing for multi-dimensional arrays, etc.
• Algorithms: Algorithms are also important as data structure. The interviewer can ask you to explain the logic behind various sorting algorithms like quick sort, merge sort, bubble sort, and searching algorithms like binary search, linear search, etc. Furthermore, you should learn dynamic programming, backtracking, recursion, and greedy algorithms. The interviewer may ask you to write code for these algorithms on a whiteboard or real-time collaborative code editor. They may give you a coding problem and ask you to craft the algorithm for that.
• Object-oriented Programming: Object-oriented programming concepts are a typical part of the coding interviews. The interviewer can test your knowledge about various OPP concepts like classes, objects, inheritance, polymorphism, encapsulation, abstraction, etc.
• System Design: Some companies conduct separate rounds for the system design interview, and some companies evaluate the basic system design skills of candidates in the condign interview. If you are fresher, you might not be asked the system design questions in the interview.

Some interviewers also discuss behavioral questions in the technical interview.

3. How will you be evaluated in a coding interview?

I’ve researched the top tech companies' evaluation criteria for the coding interview and sharing it here.

The main goal of the company is to evaluate the candidate’s ability to solve complex problems. They also look at the critical thinking skills and technical skills of the candidate.

Companies evaluate the candidate based on the following criteria:

• Problem-Solving Skills: They check the ability of candidates to understand complex problems, finding and discussing multiple solutions for the given problem. Also, they evaluate how a candidate picks up the best solution approach based on the benefits and trade-offs of the solution.
• Technical Knowledge: Evaluation based on technical knowledge refers to checking the ability of the candidate to pick the proper data structure to solve the problem, knowledge of programming languages, and core subjects of computer science.
• Testing and Debugging Skills: The interviewer also evaluates your code testing skills with various test cases and edge cases. Furthermore, they also focus on how you debug the code when the code throws any error.
• Communication: It includes how you communicate with the interviewer to clarify your doubts regarding the asked question and how you explain your logic behind the solution to the question.

4. What is the time duration and general structure of the coding interview?

The total time duration for the coding interview is 45 minutes to 2 hours, and it totally depends on the company.

Let’s see the different phases of the coding interview.

Phase 1: Introduction (5 – 7 minutes)

At the start of the interview, the interviewer and candidate introduce their selves to each other. In this phase, the interviewer is more interested in knowing about who you are, your background, your past projects, and your achievements, which you have mentioned in your resume.

Phase 2: Understanding the problem (5 – 10 minutes)

In the second phase, the interviewer gives you the coding problem and explains the problem statement and test cases properly.

Next, the turn is yours. You need to understand the problem. If you have any doubts, you need to discuss with the interviewer without any hesitation. Otherwise, you will face difficulties in solving problems in the next phase.

Phase 3: Problem-solving and writing a code (10 – 20 minutes)

In the third phase, you need to start thinking about the logic behind the problem solution. If the problem has multiple solutions, you need to discuss each with the interviewer, explain the benefits and trade-offs of each, and then you need to pick the best solution.

Also, you should continuously communicate with the interviewer so they can know your thought process while thinking about a solution and writing the code.

Phase 4: Testing and debugging (5 minutes)

After writing the code, you need to make sure that the code works correctly for all test cases. If the code doesn’t work properly, you can debug the code and show your debugging skills to the interviewer.

Phase 5: Optimization and discussion (5 Minutes)

Next, you need to discuss the efficiency of your solution code with the time and space complexity. You may discuss how you can further optimize the solution.

If you are required to solve multiple questions during the interview, you give time to the single problem accordingly.

Also, check Mastering the UMPIRE Interview Strategy in Coding: A Step-by-Step Guide to learn how to solve asked coding question in the interview.

5. Which tools do I need for coding interviews?

Companies can conduct the coding interviews on-site or virtually.

If your interview is virtual, I recommend you charge your laptop fully before the interview and make sure you have a strong internet connection. If it doesn’t have at your place, you go to a nearby cybercafe.

Also, test out platforms like Zoom, Skype, Google Meet, etc., on your device on which company is going to conduct your virtual interview. Make sure your device’s microphone and camera are working properly. Moreover, get familiar with the collaborative coding platforms that the company is going to use during the interview.

If your interview is on-site, you need to be ready by wearing a formal or casual dress and keeping a diary together if allowed. Otherwise, you will be given a whiteboard to write a code.

It is recommended to research what the company does, your job role position, and various programs of the company before you sit in the interview.

6. What Programming languages should I use for coding interviews?

The simple answer to the question is that it is not pre-decided which programming language you should use to solve the coding question. If the interviewer asks you to use a specific programming language, you should use it.

In most cases, the interviewer provides you the flexibility to choose the programming language or gives a list of programming languages, and you need to pick any one from them. If you get the flexibility to choose the programming language, you should pick the one with which you are most comfortable. So, programming language should not be a barrier to solving the problem.

Furthermore, programming language selection also depends on which company you are interviewing. For example, if you are interviewing at Oracle, you should prefer to use Java.

7. Can I use multiple programming languages to solve given problems in coding interviews?

The straightforward answer is yes.

If you are switching between multiple programming languages, you should clarify to the interviewer why you are switching the programming language. The only reason behind switching programming languages is that if you can’t write the code in the previously selected language, then the interviewer will consider that you are not well-prepared. So, it is not recommended to switch programming languages after you start writing the code without any valid reason.

However, you can select different programming languages to solve different questions. It helps you to stand out from the crowd.

8. How do I handle behavioral questions in a coding interview?

The behavioral questions are asked in the interview to check the quality and past experience of the candidate.

Whenever an interviewer asks you a question, think for a moment about the purpose of the asked question, and then reply. For example, if you are asked any question about ‘teamwork’, you should understand that the interviewer wants to understand how collaborative you are. So, you should discuss about your past team works.

It is also important to give honest answers. If you think the answer to any question has a negative impact on your profile, you should also discuss how you could overcome that kind of challenge.

9. What should I do before finishing the coding interview?

Before finishing your coding interview, you should ask the interviewer about your performance and get feedback. Also, you can ask in which concepts you are weak and focus more.

Also, don’t forget to ask for the contact details like email or how you will get the update about the next round of interviews.

Wait for 24 to 48 hours, and send a thank you email for the interview opportunity. Also, you can send a follow-up email regarding your interview results.

Furthermore, rework on the mistakes you made in the interview. If you weren’t able to answer a particular question, do more practice for such questions.

10. How should I prepare for the coding interview?

The coding interview preparation is not rigid, but it's challenging. It can take time to prepare for the coding interview according to your learning ability.

Here, I’ve given the 16 weeks of solid preparation plan for the coding interview.

General Preparation for all companies

• Week 1-2: Pick any programming language and start understanding the core concepts of computer science. Also, learn the data structures like array, string, Linkedlist, stack, queue, tree, graph, etc.
• Week 3-6: The next step is to practice the coding questions from different platforms like Hackerrank, Leetcode, codeforce, etc., for the next 4 weeks. Also, Make sure to practice the coding questions of different patterns and different data structures. Check the Grokking the Coding Interview: Patterns for Coding Questions to learn coding interview patterns.
• Week 5-6: It is also necessary to craft the projects to put in your resume. You can build projects related to web technologies, blockchain, AI data science, etc., based on your skills.
• Week 7: In this week, try to conduct mock interviews for more practice and try to solve more DSA problems. You can check Coding Mock Interviews from Designguru.
• Week 8 - 10: In these 3 weeks, you need to revise coding patterns and solve more complex DSA problems.

Start preparation for a specific company

In the next 6 weeks, you need to do preparation based on the specific company in which you want to get a job.

• Week 11: Do research about the companies’ interview process and technical rounds. Also, find what kind of questions the company asking based on the experience of other candidates. Also, understand the company culture.
• Week 12 – 15: In the next 4 weeks, you can practice coding, behavioral, and other questions related to core concepts of computer science that the company has asked other candidates.
• Week 16: This is the last week for your coding interview preparation. This week, you need to revise whatever you have learned and do more practice using mock interviews.

11. Where can I find information about the specific questions each company is likely to ask in a coding interview?

All companies have a different interview process, and each company asks different types of questions according to the job role. Anyone needs to understand what kind of questions the company asks in the interview and prepare for them.

Here, I’ve given information about how you can know which company asks what questions.

• Online Platforms: You can refer to platforms like LeetCode. They provide the company tags in each question based on the asked by the company in the past interviews.
• Interview Experience Platforms: On various platforms such as Glassdoor and Indeed, numerous individuals post about their interview encounters with particular companies. You can look up the interview experiences for the company you're preparing to interview with and gain insights from their experiences. This can provide you with a clearer understanding and expectations for your upcoming interview.
• Ask the company’s employee: You can connect with the current or former employee of the company and ask them about the interview process and questions the company asks. You can connect to current or former employees on platforms like LinkedIn.
• Look at Company Website: Some companies provide information about the interview process for each job role. So, go to the company website and explore it if you can find some useful information.

If you are applying for the junior software developer role, you may pass the interview with the knowledge of basic data structures like array, stack, and queue. But, if you are applying for the senior software developer role, you should know advanced data structures like trees, graphs, etc.

12. How do I find resources for the coding interview preparation?

As I said in the previous question, coding interview is not tough, but it's demanding. If you use good resources for the coding interview preparation, you can crack it easily. So, you must have proper resources to prepare for the coding interview.

You can find below resources to prepare for the coding interview.

• Online coding platforms: Find platforms like Leetcode, DesignGurus.io, etc., to practice coding questions.
• Books and Online courses: Find books and online courses to learn the core concepts of computer science, data structure, and algorithms. For example, check courses provided by Designguru for coding interview preparation.
• Community Groups: Join some community groups where people are discussing their interview experience with various companies. It will help you to prepare better.
• Find company-specific resources: You can also find company-specific resources conveying about the company’s interview process and practice questions.

Wrapping Up and Next Steps

I’ve explained what is coding interviews and how you will be evaluated in the coding interview. Also, I’ve explained how you can prepare for the coding interview with a proper timeline of 16 weeks and cover other most important coding interview FAQs.

Next, you can start finding good resources for coding interview preparation and start practicing the coding questions. Best of luck with your next coding interview!

You can check the courses below by DesignGurus.io for the coding interview preparation.

• Coding Interview Roadmap to prepare for coding interviews from scratch.
• Grokking the Art of Recursion for Coding Interviews to learn recursion in-depth.
• Grokking Dynamic Programming Patterns for Coding Interviews to learn dynamic programming patterns.