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Coding Interview Success: How to Prepare Effectively

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So you’ve been practicing your coding skills, built some cool projects, and now you’re ready to make your move into the professional world. Except, one hurdle stands in your way—the dreaded coding interview.

This is the part of the interview that generates the most amount of stress for potential candidates. It’s a sink-or-swim coding session that will either land you a job as a junior developer or send you back to the job board.

However, this part of the interview doesn’t have to be stressful. Proper preparation can boost your confidence and significantly improve your performance during an interview.

In this guide, I will help you boost your coding confidence and drastically improve your interviewing performance. I will help you to grasp the essential concepts, apply effective problem-solving strategies, and practice for success.

Let’s dive in and get started!

Understanding the Coding Interview Format

The format of the coding session will vary from company to company. Some companies may choose to do on-site interviews on a whiteboard.

Other companies offering remote positions may choose to simulate the whiteboarding experience by using Google Docs or Notepad.

Whatever the case may be, coding interviews typically have a few things in common:

  • They restrict (sometimes even eliminate) the typical developer tools available during the interview.
  • They usually expect you to solve LeetCode-style code challenges.
  • You are generally coding under a time constraint.
  • Most challenges can be solved efficiently using a particular data structure and algorithm.

If your heart is beginning to race a little, it shouldn’t. This is great news for us. Why? Because we can practice and prepare for this format before we even start interviewing.

Coding Interview Prep: Mastering Data Structures and Algorithms

When you first began your journey to become a junior developer, I recommended taking a computer science course to learn about DSA (data structures and algorithms).

Following this advice will pay off in spades during a coding interview. You will have a much easier time preparing for interviews, solving LeetCode-style problems, and coding more efficiently.

However, an introductory DSA course only introduces you to the concepts. What we need to do is develop mastery and command over these concepts.

Let’s take a look at how we can do that.

Reviewing Data Structures and Algorithms

Preparing for a coding interview can be a daunting task. Still, ensuring that you are well-versed in the data structures and algorithms you have learned is essential.

To do this effectively, it is vital to regularly review the details of each concept, including its functions, syntax, and potential use cases.

By incorporating these details into your preparation process, you will be better equipped to tackle any coding challenges that come your way.

Re-Invent the Wheel: Implement Data Structures from Scratch

By taking the time to create your version of a particular data structure, you can vastly improve your understanding of its underlying concepts and mechanics.

Immersing yourself in the process of building and manipulating a data structure can provide invaluable insight into its inner workings, allowing you to grasp its functionality and potential applications better.

This approach also benefits those seeking to deepen their computer science and programming knowledge, as it encourages active exploration.

Practice Solving Problems for Specific Data Structures

Another approach to deepen your knowledge of data structures is to tackle problems that are efficiently solved using them. The key is to focus on solving problems that can be solved most efficiently by using particular data structures.

To do that, you can leverage resources such as LeetCode and HackerRank to reduce the problem set to the particular data structure you’re studying. The more hands-on practice you get with them, the more you will improve your proficiency with them.

You will significantly increase your confidence and problem-solving abilities by dedicating your efforts to mastering data structures. Ultimately, this leads to greater success in your coding endeavors overall.

Coding Interview Prep: Learn Problem-Solving Techniques

When dealing with code challenges, the more we know about data structures and algorithms, the more equipped we’ll be to tackle the problem.

Sometimes, just using the correct data structure isn’t enough to make the code work as well as it needs to. Even if we have a solution that works, it might not be fast or efficient.

This is where problem-solving patterns and techniques come into play. Code challenges are almost always designed around being solved by a particular pattern, technique, or algorithm.

Using the right pattern or technique for the job will significantly improve the performance of your solution. You must learn to recognize when a specific pattern or technique can be applied to a problem.

You can utilize platforms such as LeetCode or Hackerrank to learn and practice. As you gain more experience solving problems, you will improve your ability to recognize when a particular technique should be used.

Let’s look at a couple of techniques to help get you started.

Two-Pointer Technique

The two-pointer technique is an effective method for solving problems involving linear data structures, such as arrays. You can use it to search, identify pairs, or determine if a pattern exists.

The naive approach for these kinds of problems is to use nested loops to traverse the data structure. Resulting in code that is hard to follow and performs poorly.

Naive Approach Runtime Complexity: O(n^2)

Basically, the speed of the code depends on how many things it is working on. The more things it has to process, the slower it will be, and the slowness increases exponentially with each additional thing.

We can significantly improve our code’s readability and performance using the two-pointer technique. Let’s see how it works.

Two pointer technique visualization for coding interview prep

Two-Pointer Technique Code Template

Two pointer technique for coding interview prep

Runtime Complexity: O(n)
Try it out: Valid Palindrome

Sliding Window Technique

As the name suggests, the idea behind the sliding window technique is to create a fixed-size window. The window then slides over a linear data structure to maintain a moving subset of elements.

This technique is useful when solving a problem involving repeated processing across a contiguous data set, such as finding a specific pattern or the min/max sum.

Let’s visualize it:

Sliding window technique visualization for coding interview prep

Sliding Window Code Template

Sliding window technique for coding interview prep

This example is summing the contents of the window for illustration purposes. You can perform other operations besides summation for a given problem, such as checking for a specific pattern.

Runtime Complexity: O(n)
Try it out: Maximum Average Subarray

There are many other techniques to level up your problem-solving game. However, don’t take on too much at once. Remember to get plenty of practice solving problems using a specific technique before moving on to a new one.

Coding Interview Prep: Mock Interviews and Feedback

It’s a known fact that the more you practice a particular skill, the better you get at it. Interviewing is no different. Mastering the art of interviewing is a crucial skill we must strive to develop and enhance.

An excellent approach to enhancing your interview skills is to conduct mock interviews and solicit constructive feedback from your peers. By doing so, you can gain valuable insights into your strengths and weaknesses and work on refining your technique accordingly.

This strategy can help you feel more confident and prepared for actual job interviews and increase your chances of landing your dream job. Let’s look at some available resources.

Image of Pramp website to help candidates prepare for coding interviews


Pramp is an online platform that offers mock interviews and peer-to-peer practice sessions. Their platform is designed to enhance your technical interviewing skills and problem-solving abilities.

After each session, you will receive feedback from your peers or interviewers to help identify your strengths and weaknesses. With this feedback, you can improve your skillset and better understand how others perceive you during an interview.

Taking the time to reflect on this feedback and using it to guide your preparation can significantly boost confidence and improve your chances of success.

Best of all, you can get started on Pramp for FREE!

LeetCode mock assessment for coding interview preparation

LeetCode: Mock Assessments

The mock assessments on LeetCode simulate the format and difficulty of actual coding interviews conducted by the top tech companies in the industry.

They include curated problem sets to help you prepare for various question types, such as data structures, algorithms, and more. Each assessment is timed, giving you the feel of an actual coding interview.

After completing a mock assessment, users receive detailed feedback and solutions for each problem. This will help you to understand the optimal approaches to the problems and learn from any mistakes made during the assessment.

While LeetCode does offer some free mock assessments. Most of the company-specific assessments are only available to premium users. If you’re not familiar with LeetCode, get all the details in our thorough of review of LeetCode.

LeetCode weekly and biweekly coding contests


Participating in coding contests is a fun way to prepare for coding interviews. It brings the element of surprise and the stress of time constraints.

Participating in contests is an excellent way to improve coding skills, build confidence, and gain experience solving time-sensitive problems. Additionally, the competitive nature of the contests can be a fun and engaging way to challenge yourself.

Contests are usually open to all users, and you can participate in them for free. Here are some popular contests you can participate in:


Following a consistent and dedicated approach to preparation will significantly improve your chances of performing well in coding interviews.

Remember always to research the company you’re interviewing with to identify and familiarize yourself with their coding interview format. Take the time to review data structures and algorithms you may not have used in a while or are unfamiliar to you.

Learn and practice using problem-solving techniques to enhance your problem-solving capabilities and improve the runtime efficiency of your solutions. Practice mock interviews and seek feedback to identify areas for improvement and address weaknesses.

Preparing for coding interviews can feel overwhelming at first. However, it does get much easier over time. Remember to practice regularly to maintain your coding proficiency, and never stop striving for improvement.

Happy Coding.

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