How to Start LeetCode in 2025
and get good at it
It’s 2025 and most top tech companies are still asking LeetCode style questions in coding interviews.
But getting started on LeetCode is harder than ever. With over 3,000 problems, it’s easy to feel overwhelmed and lost.
How do you even start?
Which problems should you solve?
How many problems are enough for coding interviews?
How much time should you spend on each problem?
I will answer these questions and more in this article to make your journey smoother, and lot less less painful.
For context - I’ve solved more than 1,500 LeetCode problems and cleared interviews at multiple big tech companies including Amazon, Google, and Microsoft and in this article I’ll share everything I’ve learned to help you start and navigate LeetCode more effectively.
I’ll share practical tips and resources to help you save time, stay focused and build your problem-solving skills without feeling overwhelmed.
Why do you even need LeetCode?
You might be wondering: why is everyone doing LeetCode questions. Is it really necessary to land a Software Engineering job?
The short answer is: not always.
There are plenty of startups and smaller companies that focus more on your experience with specific tech stacks and the projects you’ve built. They might not even include LeetCode style questions in their interview process.
But if your goal is to work at big tech companies like Amazon, Google, or Microsoft, you would need to practice LeetCode style questions since that’s what they ask in their interviews.
Which programming language to choose?
This is a question I get asked all the time.
Many people get stuck at deciding which programming language to use.
But here’s the truth: It doesn’t really matter. A programming language is just a tool. Once you understand the approach to solving a problem, you can implement it in any language.
In my experience giving interviews, unless the job specifically requires expertise in a certain language, you’ll be fine using any language you’re comfortable with.
The point is, LeetCode isn’t about syntax. It’s about using the right data structures, algorithms, and your ability to think critically and solve problems.
That said, if you’re new to coding, I recommend starting with Python. It’s beginner-friendly and has a simpler syntax.
If you already know a language—stick with it.
Whether it’s C++, Java, C#, JavaScript, TypeScript or Go, there’s no need to switch.
You don’t need to be an expert in your chosen language, but you should know the basics like:
variables and data types
loops (for and while)
if-else conditions
arrays and strings
functions and classes
and input/output operations
Beyond the basics, spend some time learning the built-in libraries for common data structures and algorithms.
These libraries save time and let you focus on solving the problem rather than reimplementing data structures from scratch.
For example:
Python has lists, dictionaries, and sets.
Java has ArrayList, HashMap, and PriorityQueue.
C++ offers the STL library with vector, map, and set.
Know the Fundamentals
Before diving into LeetCode problems, it’s good to familiarize yourself with the fundamentals of data structures and algorithms.
Start by understanding:
Basic Data Structures like Arrays, strings, linked lists, stacks, queues, hash tables, and binary trees.
and Fundamental Algorithms like Sorting techniques, binary search, and recursion.
Recursion is particularly important, since many problems specially tree and graph related ones rely heavily on it.
When you’re familiar with these topics, it becomes much easier to recognize which concept applies to a specific problem.
You don’t need to dive too deeply into every topic upfront. Most of your understanding will develop naturally as you solve problems.
There are plenty of resources available online to help you get started. Don’t waste time searching for the “perfect” resource—pick one and start learning.
The focus should always be on progress, not perfection.
Here are some resources I personally found quite useful:
For Data Structures: WilliamFiset’s YouTube channel
For Algorithms: Abdul Bari’s YouTube channel
For DSA Patterns: AlgoMasterIO: It’s my second channel where I upload animated tutorials on DSA and LeetCode patterns.
Here’s a comprehensive list of DSA topics you should know for coding interviews:
Learn one topic at a time
If you’re a beginner, focus on one topic at a time to avoid feeling overwhelmed.
For example: Start with arrays, the move to strings, then progress to more complex topics like linked lists, hash tables, and binary trees.
This approach helps you develop a deeper understanding of each topic and teaches you how to recognize when to use a particular data structure or algorithm.
Once you’ve learned the basics of a topic and understand how to implement it from scratch, it’s time to put your knowledge to the test.
Solve 4-5 easy problems related to that topic on LeetCode.
This will:
Reinforce your learning.
and Build confidence in applying the concepts.
If you want to learn more about how to master a DSA topic, you can check out this article where I discuss it in more detail:
Which problems should you solve?
If you open LeetCode, there are over 3,000 problems.
That number alone can feel overwhelming. So, how do you decide which ones to solve?
Start with easy problems for each topic. These are perfect for building confidence and understanding the basics of problem-solving.
Once you’re comfortable with the easy ones, gradually challenge yourself with slightly harder problems that push you beyond your comfort zone.
Remember, real growth happens when you constantly challenge yourself.
Don’t worry about hard problems in the beginning.
Most coding interviews focus on medium-level problems, so that’s where you should spend the majority of your time.
LeetCode also provides curated lists like the Top 100 Liked Problems and Top Interview 150 Problems.
These lists are excellent, and I highly recommend solving every problem on them.
How many problems should you solve?
There’s no magic number, but from my experience, 300 well-chosen problems is the sweet spot.
However, it’s not about solving just any 300 problems. Focus on high-quality problems that cover the most topics and patterns.
To make it easier for you, I’ve created a free resource: a curated list of the Top 300 LeetCode Problems organized into 60 topics and patterns that are most commonly asked in coding interviews.
You can find it on algomaster.io. Just head to the practice page. You will see a structured list of problems that you can follow from top to bottom.
Here you’ll find:
Resources to help you learn the topics.
Ability to track your progress and mark problems for future revision.
Links to GitHub and YouTube solutions.
and ability to filter problems based on pattern, difficulty level and status.
Take your time
Don’t rush through problems just to increase your count. Instead of focusing on the quantity of problems you solve, focus on what you learn from each problem.
It’s far better to deeply understand and solve 50 problems than to superficially solve 500 problems.
After solving a problem, ask yourself:
Why does this solution work?
What’s the one key insight that made everything else easier?
Also, try to make it fun. There is a fun in learning to solve coding challenges. It’s not just about getting a job.
Focus on learning Patterns
The key to getting better at LeetCode is learning as many patterns as possible.
Instead of focusing on individual questions, focus on identifying underlying patterns that connect similar problems.
On LeetCode, you’ll come across multiple problems that follow a similar patterns. Once you solve one of them, you can apply the same approach to solve others.
For example: After learning the monotonic stack pattern, I was able to solve over 10 similar problems.
I made a video covering the 15 most important LeetCode patterns I learned after solving over 1,500 problems. You can check it out later.
On algomaster.io, I’ve categorized problems by pattern. This makes it easy to focus on one pattern at a time. By going through the list, you will get to know all the important patterns for coding interviews.
How to approach a new problem?
1. Read the Problem Statement Twice
The first time, focus on getting the big picture. What is the problem asking you to do?
On the second read, pay attention to specific constraints and conditions. These small details often provide clues for optimizing your solution.
2. Analyze the Input and Output Examples
Carefully go through the examples provided in the problem.
Walk through the input and output step by step to understand how the problem works. I have found that, many times simply walking through a few examples helped me figure out the solution.
3. Visualize with pen and paper
Many problems specially the ones related to trees and graphs are much easier to understand when you draw them out.
Try to take examples that cover different scenarios and input sizes. Think about any edge cases that might come up.
4. Start with a Brute Force Approach
Don’t expect to come up with the most optimal solution right away.
First see, if you can solve the problems using a brute force approach. While it might not be efficient, it gives you a baseline to improve upon.
5. Optimize Your Solution
Once you have a brute force solution, focus on optimizing it.
Here are few things to consider:
Leverage Unused Information: Look for details you might have missed. For instance, if the problem states that the array is sorted, consider leveraging this to use binary search or a two-pointer approach.
Precompute Information: If certain calculations are repeated multiple times, consider precomputing them. Use techniques like prefix sums or frequency counts to avoid redundant calculations. Hash tables are widely used in interview questions and should be at the top of your mind.
Make Time vs. Space Tradeoffs: Sometimes, using additional memory (e.g., hash tables) can speed up your solution.
Data Structure Brainstorm: Run through the popular data structures and try to apply each one to the problem at hand.
6. Keep it Simple
Avoid overcomplicating your solution. At every stage ask yourself, "Is there a simpler way to do this?". This will not only make your solution easier to understand but it will also reduce the chances of errors during coding.
7. Analyze Time and Space Complexity
Develop the habit of analyzing the time and space complexity of every problem you submit.
How much time should you spend on each problem?
When you’re just starting out, even easy problems can take a while to solve. That’s completely normal—don’t get discouraged if you can’t come up with a solution right away.
Your main goal in the beginning should be to focus on learning and understanding the problem deeply. Real progress happens when you take the time to think, make mistakes and refine your approach.
But, some problems involve specific tricks or patterns that are hard to figure out unless you’ve seen them before.
Spending hours on such problems without progress can be counterproductive.
Here’s a good rule of thumb:
Give yourself 30 to 60 minutes of focused effort for each problem.
If you’re still stuck, it’s okay to look at hints or solutions.
Read the official solution and and try to understand the top voted solutions on LeetCode discussion forum.
Don’t just move on after viewing the solution. Try to grasp why the solution works.
Rewrite the solution from scratch without looking at the code. Writing it yourself helps you internalize the approach and ensures you truly understand it.
If you couldn’t solve the problem on your first attempt, mark it for revision and revisit it after a few weeks. Revisiting problems helps reinforce your understanding and ensures long-term retention.
Avoid Memorization
One of the most common mistakes—one that I made myself—is memorizing solutions to difficult problems and moving on.
At first, it might seem like a shortcut, but in reality, it’s a big mistake for three main reasons:
You’ll quickly forget memorized solutions. Without understanding the logic behind them, they won’t stick in your memory.
Your problem-solving skills won’t improve. Memorization skips the critical thinking process, which is the real value of practicing coding problems.
You’ll struggle in interviews. Most interviewers ask variants of problems or follow-up questions, and without a deep understanding, you won’t be able to adapt.
Instead of memorizing, focus on understanding the solution, even if it takes hours.
Break it down step by step and ask yourself:
Why does this approach work?
What’s the key insight that simplifies the problem?
How can I apply this approach to similar problems?
This effort pays off in the long term. The deeper your understanding, the more confident you’ll feel explaining your thought process during interviews.
Practice in a timed environment
Solving a problem during an interview is very different from solving it from the comfort of your home.
That’s why it’s a good idea to time-box yourself and practice in a timed environment after you have learned the basics and solved 100-150 problems.
Simply turn on a timer while practicing and try to complete the problem within that time.
For easy problems, aim to complete them in 10-15 minutes.
For medium problems, set a timer for up to 30 minutes.
For hard problems, allow yourself up to an hour.
To take your practice a step further:
Participate in LeetCode contests.
Try virtual contests by simulating past LeetCode contests.
It’s okay if you struggle to solve even one problem initially—this is normal. The goal is to gain experience solving problems within a time limit.
When I started participating in contests, I could only solve 1-2 problems. But with consistent practice, I improved to solving 3 problems, and eventually, I was able to solve all of them in some contests.
Retain what you Learn
Getting good at LeetCode isn’t just about learning new concepts or solving problems—it’s also about retaining that knowledge over time.
That’s why you should regularly revisit concepts and problems you’ve already solved, especially the ones you found challenging.
Try to solve those problems again without looking at the solution.
By practicing consistently and revisiting old problems, you’ll make it much easier to retain what you’ve learned over time.
I discuss more about how to effectively revise LeetCode problems in this article, so make sure to check it out:
Be Consistent
Getting good at LeetCode takes time.
Some topics might take weeks or even months to master, and that’s okay.
Be patient with yourself and remember: It’s completely normal to feel stuck or frustrated when working on a tough problem or grasping a complex topic.
If a problem feels too hard, take a break, then come back to it with a fresh perspective.
The more you practice, the better you will get at solving LeetCode problems.
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I hope you have a lovely day!
See you soon,
Ashish
Thank you
Awesome! Really good and quality article!