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Exploring LeetCode: The Best Coding Interview Prep Tool

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If you’ve ever searched online for tips on preparing for a coding interview, you’ve likely come across LeetCode. It’s a popular online platform that provides a collection of coding challenges that can help to improve your programming skills.

LeetCode supports various programming languages like Java, Python, and C++, among many others. The challenges are divided into different difficulty levels and cover a wide range of topics.

Each coding challenge provides a problem statement, constraints, expected outputs, and sometimes additional hints. When you have solved a problem, the solution undergoes a series of tests that evaluate its completeness and efficiency.

In addition, the platform has a supportive community where users can discuss solutions and learn from one another. LeetCode brings together programmers and enthusiasts from around the world, enhancing your learning experience and encouraging collaboration.

Furthermore, LeetCode offers learning resources about specific data structures, algorithms, and useful programming techniques. Additionally, you will find curated lists of practice questions for interviews with top companies like Facebook, Google, and Microsoft.

Overall, LeetCode is a valuable tool that you can leverage to enhance your problem-solving skills and success in technical interviews. So, let’s take a deeper look at what LeetCode has to offer.

LeetCode sign up form

LeetCode Sign Up Form

Signing up for LeetCode is straightforward. You create a username, set a password, and provide your email address. Alternatively, you can simplify the process further by signing up with your Gmail, GitHub, or Facebook account.

After signing up, a welcome wizard will prompt you to provide basic information regarding your objectives. This step is optional, and you may choose to skip it if you prefer.

After completing the wizard, LeetCode offers a thoughtfully selected set of challenges to new users. This helps to ease the process of joining the platform for newcomers.

LeetCode user interface

User Interface

The platform is designed to offer a seamless and interactive user experience. When you log into LeetCode, you are welcomed by a user-friendly interface that is easy to navigate. The straightforward navigation system enables you to browse through different sections of the website efficiently.

There are various options available for you to explore, such as problem sets, explore cards, discussion forums, and more. Now, let’s dive into the main feature that brings users to Leetcode; their coding challenges.

LeetCode problem list

Coding Interview Challenges

Many users sign up for LeetCode mainly for its problem sets, which serve as the core of the platform. It is where users can focus on their interview preparation and hone their problem-solving skills. As such, users tend to spend most of their time here.

The problems are presented as a table identifying whether it has a solution, acceptance rate, and difficulty level. If you’re a premium subscriber, you can also see the frequency of the problem appearing in interviews.

You can re-order the problem list with these fields to fit your specific goals and needs. Additionally, you can filter out problems based on their status and apply tags to narrow them down to specific problem types.

Suppose you want to focus exclusively on solving array problems using the two-pointer technique you’ve previously attempted but have yet to solve. You can do that, which is pretty neat and a powerful feature to have at your disposal.

LeetCode Two Sum coding challenge for coding interview preparation

Solving a LeetCode Challenge

Each code challenge clearly defines the problem statement, example inputs, expected outputs, and the constraints to consider in your solution. Best of all, you don’t need to leave your browser when you’re ready to code.

The problem page has a built-in code editor supporting many programming languages. However, this bare-bones editor doesn’t provide the assistance you typically get when working in your chosen IDE.

You must remember all syntax and language features you intend to use to solve the problem. You may be frustrated by this at first; however, it does represent the coding part of an interview very well.

In my previous post, Unveiling the Coding Interview, I explained that many interviewers restrict the tools typically available while working. To challenge candidates, they often ask them to code on a whiteboard (in-person interview) or in Notepad or Google Docs (if the interview is remote).

When you’ve finished coding your solution, you can click the Run button to test your solution against the example test cases. If there are any problems with your answer, the page will report the type of error it encountered. Informing you of the failed test case and what you need to fix.

When you’re confident in your solution, you can submit your answer, which will run more exhaustive tests against your solution. If your answer is accepted, you will receive a detailed runtime analysis highlighting the performance of your solution. Otherwise, as with the ‘Run’ button, you will receive a brief report indicating any issues you must fix.

LeetCode challenge editorial for coding interview preparation

Editorials

Some challenges may have an editorial associated with it. The editorial will provide an overview of the problem statement and detailed explanations for solving it, including its complexity analysis.

The first approach is typically the naive approach, also known as the “brute force” solution. This particular approach often has a high time and space complexity. It may even time out when tested against larger sets of data.

In each editorial, the following approach will usually be more efficient than the previous one. It may be using a more efficient data structure or a specific technique to improve the solution’s performance.

Even if LeetCode accepts your solution, reading the editorial and discussion is always a good practice. You may discover a more efficient way to solve the problem or learn a new technique to add to your toolkit.

Learning Resources: LeetCode Explore

But what if you are unable to solve some problem types on LeetCode? This indicates that you have some learning gaps in your studies that you should work on.

Luckily, LeetCode’s offering provides an Explore section to help us prepare for upcoming interviews and learn more about data structures, algorithms, and techniques to add to our arsenal.

The Explore section of the website is divided into three categories, Featured, Interview, and Learn. Let’s take a brief look at these offerings.

Featured LeetCode explore cards for coding interview preparation

LeetCode Explore: Featured

The Featured section includes a handful of explore cards. These are a mix of available courses and upsells that a user may be interested in.

Please be aware that certain courses are only available to Premium subscribers, and others require purchase. However, having a premium subscription gives you a hefty discount on these courses, such as LeetCode’s Interview Crash Course series.

Despite this, there are still numerous free options available for you to choose from.

LeetCode explore card for preparing for top tier technical interviews from Google, Facebook, Microsoft and Amazon

LeetCode Explore: Interview

Moving onto the Interview section of LeetCode Explore, we have another curated collection of cards to choose from. These cards will mainly cater to those preparing for interviews with specific companies such as Google, Amazon, Facebook, etc.

Most of these cards require a premium subscription plan, so this section will be less helpful for a freemium subscriber. Even though freemium subscribers have limited access, some useful courses are still available for them here. Including those covering behavioral aspects of interviews, top interview questions, and strategies for success.

LeetCode explore card for learning data structures and algorithms

LeetCode Explore: Learn

This section is the most useful to freemium subscribers. Users not subscribed to a premium membership can access most explore cards in this section.

Here, you can enhance your problem-solving skills by acquiring knowledge of data structures, algorithms, and various programming techniques. Each course provides plenty of hands-on practice as they’re often associated with specific problems to drive the point of the lessons home.

As you progress, more lessons within the course begin to unlock. To ensure success, complete all tasks and problems before moving on to the next section.

I often refer back to this section when I encounter problem types I need help solving. Usually, this happens because of a lack of understanding of a particular topic.

The explore cards have been extremely useful in broadening my knowledge and advancing my progress when stuck.

Coding Interview Preparation

LeetCode online interview for coding interview preparation

LeetCode Online Coding Interview

LeetCode’s online interviews allow you to set up mock interviews to simulate and get practice in a realistic environment.

Creating an interview is straightforward; just name it, and then you can start setting up the interview. A whiteboarding tab is automatically created for you, which you can set up according to your preferences.

Additionally, you can add as many LeetCode challenges as you want to your interview. You can even create user interface design challenges with popular technologies like React and Vue.

To make the most of your online interview, you can easily invite someone to join by sharing the interview link with them. Once a user joins, you can start a call and begin the interview.

However, there are limitations to the usage of this feature. You can only create a single active interview at a given time. If you want to make a new interview, you must end your current one.

Furthermore, interviews are limited to ten monthly sessions, each with a 3-hour time limit beginning when a user joins. If you have exceeded the usage limitations, you must wait until the next month to use your interview again.

If you want to reset the usage limits, you can opt to end the current interview and start a new one. This way, you can keep hosting your interview sessions without any interruptions.

LeetCode mock assessment for coding interview preparation

LeetCode Mock Assessment

The assessment section of the site allows you to prepare for interviews using a collection of questions from actual companies. You can choose to do an online, phone, or onsite interview assessment.

Freemium subscribers can only choose the cards containing random questions. They claim to be derived from actual companies; however, we don’t know which ones.

If you’re a premium subscriber, you can choose assessments with questions from top-tier companies like Google and Facebook.

I found distinguishing between the Online Assessment, Phone Interview, and Onsite Interview cards difficult. All of them have the same structure, and only the style of the question varies.

For example, during a phone interview assessment, you won’t be speaking to anyone as you would in an actual phone interview. Instead, you’ll answer a few questions in the same format as you would when solving any other problem on LeetCode. Of course, this excludes helpful hints, editorials, and discussions.

I found it strange because you usually won’t be asked to complete a code challenge during a phone interview. A phone interview typically involves a technical questionnaire or simply a casual conversation with the company’s recruiter.

Although primarily designed for premium subscribers, this section is a valuable addition to your interview preparation resources. However, premium subscribers will get the most out of this feature.

LeetCode weekly and biweekly coding contests

LeetCode Contests

LeetCode contests are enjoyable events that involve competing against other users in timed coding challenges. These contests test your problem-solving skills, algorithmic thinking, coding speed, and accuracy in a competitive setting.

Participating in a contest will test your ability to solve coding challenges within a specific time limit. These contests usually range from a few hours to a couple of days, depending on the type of contest you have joined.

The accuracy and speed of your problem-solving will determine your contest score. The scoring system rewards both precise solutions and efficient code. So, keep that in mind.

When you finish a contest, you can see your score and ranking on a live leaderboard, which updates in real time as participants submit their solutions. The leaderboard allows you to track your progress and compare your performance against your peers, fostering a sense of community and healthy competition.

Contests offer a thrilling challenge for coding enthusiasts to learn from peers and showcase their skills. It’s an excellent opportunity for personal growth and friendly competition.

It is crucial to keep in mind that coding interviews are intentionally competitive. Even if you’re not a fan of programming contests, participating will improve your performance under the pressure of time constraints.

Pricing Plans

LeetCode offers both a free tier subscription as well as a premium option to their users.

LeetCode’s free tier offers users a vast array of coding challenges of varying difficulty levels. Users can tackle these problems, submit their solutions, and receive prompt feedback on the accuracy and efficiency of their code.

Additionally, free-tier users can join community discussions and access essential features like explore cards, contests, and more. Even without a premium subscription, they offer a significant number of features.

LeetCode’s premium subscription offers additional features and benefits for users who desire an enhanced learning and practicing experience. As a premium subscriber, users gain access to exclusive features such as:

  • Access to premium content
  • Ability to sort problems by prevalence
  • Unlimited playgrounds
  • Video solutions
  • Additional discounts (more on that later)
  • and many more

Please visit the official LeetCode website for an exhaustive list of all the extra features a premium subscription offers.

At the time of this writing, you can sign up for a premium subscription for a monthly payment of $35/mo or a yearly subscription for $159. That’s $13.25 per month, which is significantly lower; I highly recommend going with the annual subscription if you can swing it.

Keep in mind that these details are subject to change and may vary. Visiting their website is recommended for the most up-to-date subscription plans and pricing.

Pros

  • LeetCode offers a vast collection of coding challenges covering many topics of varying difficulty, allowing users to practice and strengthen their problem-solving prowess.
  • Regularly solving problems on LeetCode can help users gain mastery of common data structures and algorithms.
  • Curated lists of coding challenges help users sharpen and build confidence in their interviewing skills.
  • Detailed feedback on your code’s correctness and efficiency will help you become a better programmer.
  • The yearly premium subscription plan is very affordable.
  • LeetCoins. That’s right; you can pay for your monthly membership entirely in LeetCoins.

Cons

There are not many cons to using LeetCode; however, there are a few that are worth mentioning:

  • The monthly premium subscription of $35/mo is expensive.
  • Remember the additional discounts for premium subscribers we mentioned earlier. That’s right, some content is still behind a paywall, even with a premium subscription.
  • The platform’s primary focus is on data structures and algorithms. It provides very little coverage of other topics.

My biggest concern with LeetCode is its pricing strategy. For $35/mo, I expect access to all content. I was disappointed to discover that some content is still behind a paywall, even with a premium subscription.

For instance, LeetCode’s Interview Crash Course: Data Structures and Algorithms course is $89.99 without a subscription. With a subscription, it’s still $44.99. While that is a heavy discount, it’s still A LOT of money for access to one course.

Want to take their System Design for Interview and Beyond course? It’s $94.99 for freemium subscribers and $54.99 for premium subscriptions.

Although LeetCode provides valuable resources for both free and premium members, it would be better if premium members had access to all available content.

Final Verdict

As a software developer seeking to sharpen your problem-solving abilities in technical interviews, I highly recommend LeetCode. The platform offers a wide range of coding challenges, interview preparation, and a supportive community.

Consistently using LeetCode can enhance your ability to think algorithmically, gain expertise in data structures and algorithms, and improve the efficiency of your code. Most users will enjoy using the platform even if they only use the free version. It’s entirely up to you whether or not you want to upgrade to a premium membership.

I have been a LeetCode member for several years and a premium member for the past year. The platform has been a valuable tool in improving my capabilities as a developer and has significantly transformed my performance in coding interviews.

Does every reader need to have a premium membership to LeetCode? No, the free version offers a ton of content that will keep you engaged for quite some time.

Suppose you plan on getting a premium subscription. In that case, it’s better to opt for the yearly subscription as it is more cost effective, especially since some content is still behind a paywall.

Is LeetCode the only interview preparation resource that you’ll need to succeed? In short, no.

Although LeetCode helps immensely with algorithmic problem-solving, you should consider looking for resources to improve your knowledge in other areas. Supplementing your LeetCode practice with a well-rounded learning curriculum will serve you best.

Closing Statements

As always, feel free to discuss the topics in the comments, and remember to subscribe to my newsletter.

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Until next time.

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