Is it good to look at LeetCode solutions?

Yes, looking at LeetCode solutions can be helpful, but only if used strategically and at the right time in your learning process. While it’s tempting to check the solution whenever you get stuck, there are both pros and cons to this approach. Here’s a breakdown of when it’s good to look at LeetCode solutions and how to do it in a way that maximizes your learning.

1. When It’s Good to Look at LeetCode Solutions

a. After You’ve Given It a Solid Effort

• Time to Try on Your Own: It’s important to try solving the problem on your own first. Give yourself enough time to think through the problem (e.g., 30-60 minutes for Medium/Hard problems). Struggling with a problem helps you develop problem-solving skills and deepens your understanding.
• Benefits of Struggling: Working through difficulties builds resilience and helps you learn how to approach problems from different angles. By attempting the problem without help, you're more likely to retain what you learn.

b. To Learn New Techniques or Optimizations

• Learning New Algorithms: If the problem involves a concept you’re unfamiliar with (e.g., dynamic programming, segment trees, or backtracking), looking at the solution can teach you new techniques and introduce you to advanced algorithms.
• Optimization Techniques: You may solve a problem but want to learn a more efficient approach. Reviewing solutions allows you to compare your approach with optimal ones, helping you understand time complexity and space complexity better.

c. When You’re Completely Stuck

• Avoid Frustration: If you've spent a considerable amount of time on the problem and are completely stuck, checking the solution can help you get unstuck. Use it as a learning tool, not as a shortcut.
• Understanding Edge Cases: Sometimes, the solution helps clarify edge cases that you missed in your implementation. This is especially useful for learning how to handle tricky inputs.

d. After You’ve Solved the Problem

• Compare Approaches: Once you’ve solved a problem, it’s a good idea to look at the official solution or community solutions to see if there’s a better or more optimized way to solve it. This will expand your understanding of how to approach similar problems.
• Learn Different Patterns: Often, there are multiple ways to solve a problem, and by checking the solution, you can see different patterns and strategies that you might not have thought of.

2. Benefits of Looking at Solutions

a. Learning New Problem-Solving Techniques

• Expand Your Toolbox: Every time you look at a solution, you’re adding new techniques and strategies to your problem-solving toolbox. Over time, this helps you recognize patterns and apply them to other problems.

b. Understanding Time and Space Complexity

• Efficient Solutions: LeetCode solutions often explain the time and space complexity of different approaches. By studying these solutions, you can learn how to write more efficient code, which is crucial for technical interviews.

c. Debugging Your Own Code

• Spot Mistakes: If you’ve written code that isn’t working, looking at the solution can help you identify where you went wrong. You can then compare your approach and correct any misunderstandings or mistakes in logic.

d. Building Confidence

• Clarification: Sometimes looking at the solution gives you the clarity you need to understand a concept more deeply. This can boost your confidence, as you’ll be better equipped to tackle similar problems in the future.

3. When It’s Not Good to Look at LeetCode Solutions

a. Too Early in the Process

• Avoid Dependency: If you get into the habit of looking at solutions too early, you risk becoming dependent on them. This can prevent you from developing your own problem-solving skills. Always make an effort to solve the problem on your own first.
• Skipping Problem-Solving Process: The learning happens in the process of struggling and trying different approaches. By skipping this process, you miss the opportunity to build the critical thinking needed for real coding interviews.

b. Using Solutions as a Crutch

• False Sense of Progress: Constantly relying on solutions can create a false sense of progress. You may feel like you understand the solution at the moment, but if you encounter a similar problem later, you might struggle because you didn’t internalize the problem-solving process.
• Memorizing Solutions: Don’t try to memorize the solution. Instead, focus on understanding the logic and the steps involved. Interviews rarely present the exact same problems, so memorization won’t help in the long run.

4. How to Look at Solutions Effectively

a. Understand the Logic

• Step-by-Step Understanding: Don’t just copy and paste the solution. Break it down into steps and try to understand the reasoning behind each step. What is the core logic of the solution? How does each part of the code contribute to solving the problem?

b. Re-implement the Solution

• Write It on Your Own: After reviewing the solution, try to re-implement it from scratch. This forces you to actively engage with the solution and internalize it rather than passively reading it.
• Use Comments: Comment the code as you write it, explaining to yourself what each part of the solution does. This ensures you truly understand the problem.

c. Compare Solutions

• Multiple Approaches: Look at more than one solution (e.g., the official solution, community solutions, or even YouTube tutorials) to understand different ways of solving the problem. This will expand your understanding of problem-solving techniques.
• Optimize Your Approach: If you find a more efficient solution than yours, understand why it’s better and how it optimizes time or space complexity. Try to implement that in your future attempts.

5. How to Use LeetCode Solutions for Long-Term Learning

a. Focus on Problem-Solving Patterns

• Recognize Patterns: Many LeetCode problems share common patterns (e.g., sliding window, two-pointer techniques, dynamic programming). When looking at solutions, pay attention to these patterns so you can recognize and apply them to new problems in the future.

b. Practice Similar Problems

• Practice Variations: After understanding the solution, try solving similar problems to reinforce the concept. This will help you apply the learned techniques in different contexts.

c. Reflect and Review

• Write Down Key Insights: After reviewing a solution, write down the key insights you gained. For example, what algorithm or technique was used, and how did it improve the solution?
• Revisit Later: Revisit the problem after a few days or weeks and try solving it without looking at the solution again. This helps reinforce the concept and ensures long-term retention.

Conclusion

Looking at LeetCode solutions can be highly beneficial if done correctly. It’s best to first try solving the problem on your own, and if you get stuck or want to learn a more optimized solution, then consult the solution. The key is to understand the logic behind the solution, re-implement it, and apply the techniques you learn to other problems.

Use solutions as a learning tool, not as a shortcut, and over time, you’ll build the problem-solving skills necessary to excel in coding interviews.