How many LeetCode questions should I solve?

The number of LeetCode questions you should solve depends on your goals, experience level, and the type of technical interview or competition you're preparing for. While there’s no exact number that guarantees success, a strategic mix of Easy, Medium, and Hard problems across key topics can help you become proficient and confident in problem-solving.

1. How Many LeetCode Problems Should You Solve Based on Experience Level?

Beginners (100 to 150 Problems)

• Goal: Build foundational knowledge of algorithms, data structures, and problem-solving skills.
• Breakdown:
  • 60-80 Easy Problems: Focus on mastering the basics like arrays, strings, and linked lists.
  • 30-50 Medium Problems: Start transitioning to more complex topics like recursion, trees, and basic dynamic programming.
  • 10-20 Hard Problems: Attempt a few hard problems to challenge yourself and push your understanding of more advanced concepts like graphs, backtracking, and advanced dynamic programming.

Intermediate (200 to 300 Problems)

• Goal: Improve problem-solving speed, efficiency, and ability to handle Medium and some Hard problems.
• Breakdown:
  • 50-70 Easy Problems: Use Easy problems to refresh your basics and serve as warm-ups.
  • 100-150 Medium Problems: Focus the majority of your time on Medium-level problems, as these are most common in interviews.
  • 30-50 Hard Problems: Solve Hard problems to develop advanced problem-solving strategies and optimize your algorithms.

Advanced (300 to 500+ Problems)

• Goal: Master advanced problem-solving and algorithm optimization for high-level technical interviews.
• Breakdown:
  • 30-50 Easy Problems: These should feel more like warm-ups and help reinforce key concepts.
  • 150-200 Medium Problems: Medium problems should be your primary focus, as they represent the bulk of technical interview questions.
  • 100-150 Hard Problems: Spend significant time tackling Hard problems, especially if you’re targeting top-tier companies (e.g., FAANG) or senior-level positions.

2. How Many LeetCode Problems for Specific Goals?

1. FAANG and Top-Tier Company Interviews (250 to 350 Problems)

• Focus: Medium and Hard problems.
• Breakdown:
  • 50 Easy Problems: These help reinforce your understanding of fundamental concepts.
  • 150-200 Medium Problems: Spend most of your time on these, as they represent the majority of questions asked by companies like Google, Facebook, Amazon, and Microsoft.
  • 50-100 Hard Problems: Ensure you solve enough Hard problems to be prepared for more complex interview questions.

2. General Technical Interviews (150 to 200 Problems)

• Focus: Easy and Medium problems with a few Hard problems.
• Breakdown:
  • 50 Easy Problems: Use these to build confidence and solidify foundational skills.
  • 80-100 Medium Problems: Cover common interview topics like binary search, dynamic programming, and tree traversals.
  • 10-20 Hard Problems: Tackle a few Hard problems to ensure you’re prepared for occasional tough interview questions.

3. Competitive Programming or Mastery (500+ Problems)

• Focus: Hard problems and optimizing algorithms.
• Breakdown:
  • 200-300 Medium Problems: Regularly solving Medium problems will improve your problem-solving speed.
  • 150+ Hard Problems: Competitive programming often requires the ability to solve highly complex problems under time constraints. Tackling a large number of Hard problems will prepare you for this.

3. Key Topics to Cover While Solving LeetCode Problems

Make sure to cover a wide range of topics to ensure well-rounded preparation for coding interviews:

• Arrays and Strings: Basics like array manipulation, sliding window techniques, and string operations.
• Linked Lists: Insertion, deletion, and traversal problems.
• Trees and Graphs: Tree traversal (DFS, BFS), binary trees, and common graph problems (shortest path, topological sort).
• Dynamic Programming: Solve common DP problems like knapsack, longest increasing subsequence, and coin change.
• Recursion and Backtracking: Key for solving constraint satisfaction problems like permutations and combinations.
• Sorting and Searching Algorithms: Practice binary search and quicksort.
• Hash Tables: Efficient lookup operations using hash maps.
• Bit Manipulation: Problems involving bitwise operations like finding unique elements or subsets.

4. How to Approach Solving LeetCode Problems

a. Quality Over Quantity

• Focus on truly understanding each problem rather than rushing through as many as possible. After solving a problem, review your solution, check for edge cases, and optimize the code if needed.
• Review Solutions: Compare your solution with others on LeetCode Discuss to learn different approaches and optimizations.

b. Focus on Problem-Solving Patterns

• Many coding problems follow similar patterns. By solving a sufficient number of problems, you’ll start recognizing these patterns (e.g., two-pointer technique, sliding window, dynamic programming).

c. Progress Gradually

• Start with Easy problems to build confidence, then move on to Medium and eventually Hard problems. As you get more comfortable, increase the complexity of the problems.

d. Simulate Interview Conditions

• Practice solving problems within a set time limit to simulate the pressure of real interview scenarios.
• Use platforms like LeetCode Premium or Pramp to perform mock interviews under real-time conditions.

5. Common Pitfalls to Avoid

• Memorizing Solutions: Instead of memorizing problem solutions, focus on understanding the logic behind them. Interviews often present variations of common problems, and understanding the underlying concepts will help you adapt.
• Skipping Topics: Avoid focusing solely on problems you're good at. Make sure to cover all important topics like dynamic programming, graphs, and trees, even if they’re more challenging for you.
• Inconsistent Practice: Consistency is key. Set a daily or weekly goal and stick to it, whether it’s solving 3 problems a day or 15 problems a week.

6. Conclusion

The number of LeetCode problems you need to solve depends on your current level, goals, and the type of interview or competition you're preparing for. Here's a quick recap:

• Beginners: Solve 100 to 150 problems with a focus on Easy and some Medium problems.
• Intermediate: Aim for 200 to 300 problems, focusing primarily on Medium problems and tackling Hard ones.
• Advanced: Solve 300 to 500+ problems, including a large number of Medium and Hard problems to master advanced concepts.

By focusing on consistent daily practice and covering a diverse range of topics, you can build the problem-solving skills necessary to succeed in technical interviews or competitive programming.