Coding Interview Questions

First of all, congratulations on securing an interview. Your prospective employer loved your resume and wants to learn more about you. It’s perfectly normal to feel both excited and nervous. It just means you’re passionate about the role and want to succeed.

The good news is that on paper, you’ve already landed the job. All that’s left to do is demonstrate your knowledge of coding in person, connect with the employer, and prove you’re a great team player with solid communication skills.

Remember, a coding interview isn’t a one-way street. The interview is also a chance for you to find out more about the coding position, meet some of the people you’ll be working with, and explore your new work environment.

This article aims to fully prepare you for your coding interview and maximize your chances of success.

How To Prepare Yourself for a Coding Interview

By putting in that extra effort things will run much smoother. Here are 5 things to consider to help you nail your coding interview:

Do Your Homework

Learn as much as you can about the company and the position, but also learn about yourself. Review your qualifications and coding skills that make you eligible for the position. Know your strengths and make sure you have a story that demonstrates those strengths.

If the job description doesn’t provide much detail, try to find further information on sites like LinkedIn, Indeed, or Glassdoor. You can look at similar coding roles for a more comprehensive job description.

You need to know your prospective employer like the back of your hand. Visit the company website and go through their about us section. Google the company name, research their products, services, and business goals. Read what their employees have to say about working there.

These steps will not only prepare you for the interview but can also help you assess yourself and get a better understanding of your dream job.

Make a Good First Impression

The importance of making a good first impression with your prospective employer cannot be stressed enough. And not just with the person asking the questions.

Make sure you take advantage of every opportunity to indulge in friendly small talk with anyone you meet, even if they’re not directly related to getting you a coding gig. The security guards who check you in, the assistants, the receptionists, even the janitor. Everyone deserves to be treated with respect and kindness.

Dress to Impress

Even if you’re applying for an entry-level coding position, dress like you’re interviewing for a senior engineering role. Usually a well fitted, professional outfit is all you need. Keep in mind that a suit might not be a good choice at some workplaces, such as tech start-ups or even at Google for that matter. Use your knowledge from your research on the company.

Some interviews are held using remote video conferencing tools like Zoom and Skype. This doesn’t mean you can take shortcuts in the wardrobe department. Dress the same as you would for a face-to-face meeting.

Be Punctual

Aim to arrive 10 to 15 minutes early. Checking in too early can be awkward and result in wasted time. Obviously, don’t be late either: plan ahead for traffic and parking delays.

If it’s your first time making the journey and you’re not sure how long it’ll take, allow yourself an extra hour. If you arrive at the venue early you can take a walk or grab a coffee beforehand.

If your interview is being held over Zoom, as so many are these days, test out your camera and audio ahead of time with a practice call. That way you can log in and be ready to go at your scheduled time.

Conduct a Mock Interview

A mock (or practice) interview is a great way to calm the nerves and set yourself up to succeed. If you know someone who has experience interviewing people, tap into that expertise and ask for a few practice questions with feedback. If not, call up friends or family.

You can even write out a few questions and practice answering them by yourself - but be sure to actually say your responses out loud to get the most out of your practice time. All you need is a video camera. A phone or webcam on your computer will suffice. Seeing yourself on the screen might initially make you feel awkward or anxious, which is quite normal. This exercise is a good way to get over the shyness before you step into the real interview.

Here’s how you can conduct your own mock interview:

• Make a list of interview questions and sort them in order of importance.
• Record yourself reading the questions.
• Transfer the footage to your computer, this will serve as your interviewer.
• Play the footage and record yourself while you answering the questions.
• Take regular breaks and restart if you get something wrong.
• Play the footage and review your performance.

While reviewing your performance, notice if:

• you answered the questions completely, and if those answers were convincing.
• your answer was clear and concise.
• you were fidgeting or moving your hands a lot.
• there was any dead air or excessive use of fillers such as 'um,' 'aah,’ ‘actually,’ etc.
• you maintained eye contact with the camera throughout the mock interview.

Take note of everything that you would like to add or change. Put in some work, pat yourself on the back, invite yourself for another interview, and repeat the next day. You can repeat this process until you feel confident enough for the actual interview.

Example Behavioral Questions for a Coding Interview

Often starting with the phrase “Tell me about a time when…,” behavioral questions are asked to understand how you have handled tricky work circumstances in the past. This helps the interviewer predict your likely performance in the company if selected.  

We suggest you use the STAR method for answering behavioral questions. STAR stands for

• Situation: Describe a situation in which you faced a challenge. For example, you had a dispute with your manager or a co-worker while working in a group project.
• Task: Describe what your task was in that situation. Continuing with the example of the situation, your task was to settle a dispute with a co-worker.
• Action: Describe how you planned to complete the task and put your plans into action. You sat down with your co-worker and talked about what was bothering you over a cup of coffee.
• Result: Describe the outcome of the action taken. You reconciled with your co-worker.

Some of the common behavioral questions asked are:

• Tell me about a time when you worked well under pressure.
• Tell me about a time when you handled a mishap at your workplace.
• Have you ever made a decision that did not go well with others? How did you handle it?
• Tell me about a project where you worked in a team.
• Tell me about a time when you experienced failure.

Technical Coding Interview Questions

A coding interview can include technical questions or even a short exam. Be prepared for some coding questions related to your area of expertise. This does not mean that the behavioral questions are to be ignored completely. We advise you to spend at least two-thirds of your time preparing for questions based on technical aspects of the role.

You can expect most of the technical questions to be on programming languages, coding techniques, data structures, and algorithms. You must have a good understanding of searching and sorting techniques, linked lists, graphs, and trees.

Some of the common questions are:

• How will you reverse a linked list?
• How will you find the length of a singly linked list?
• How will you implement a bubble sort/merge sort algorithm?
• How will you implement a binary search tree?
• Can you write a program to count the number of leaf nodes in a binary tree?

If you’re into coding, you’ll understand the difference between a functionally correct program and an efficient and functionally correct one. Interviewers look for candidates who can write efficient programs that run fast and use minimal resources. If you feel your coding skills are rusty, then make sure you brush up on how to optimize code.

Questions on Computer Science Fundamentals

Computer science related questions can be used to distinguish exceptional candidates from those who have just memorized common definitions or algorithms. Make sure you’re up-to-date on operating systems, distributed systems, networking, hardware, software, computer graphics, and other computer science topics, and you’ll be good to go.

Some of the common questions are:

• What is a kernel, microkernel, macro kernel, and monolithic kernel?
• What is virtual memory?
• What is caching?
• What are microservices?
• Can you name one real-world example of a distributed computing system?

Good Luck in Your Future Coding Career

There’s so much more to coding interviews than what’s been covered here. But we hope this post gave an introduction and provided you with a good selection of example coding interview questions. To learn more about how to prepare for a coding interview you can enroll in our coding interview skills course.

Alternatively, if you’re yet to secure an interview and serious about coding, kickstart your career with our Software Engineering bootcamp. We’ll teach you all the skills you need to land a coding job with a great salary. Our mentors will support you every step of the way as you work through our professionally-design curriculum, and learn what a coder does day to day.

For further reading, take a look at our software engineering blog. We post regular articles on coding-related topics like coding best practices and how to become a professional coder.