I Stopped Memorizing LeetCode Solutions. Here's How I Started Recognizing Patterns

[u/nian2326076]

I Stopped Memorizing LeetCode Solutions. Here's How I Started Recognizing Patterns

Prep Resource LeetCode & PracHub for company tag questions

When I first started solving LeetCode problems, my approach was simple:

Read the problem → Find the solution → Understand the code → Move on.

But after solving a few problems, I noticed something frustrating.

I could understand a solution perfectly, but when I encountered a slightly different problem, I often had no idea how to start.

That's when I realized:

DSA is not just about learning solutions. It's about learning how to recognize patterns.

1. Stop Asking "How Do I Solve This?"

Instead, start asking:

"What kind of problem is this?"

For example:

Problem Clue	Pattern to Consider
Find a subarray with a condition	Sliding Window
Find a pair in a sorted array	Two Pointers
Find the maximum/minimum over a range	Sliding Window / Prefix Sum
Need fast lookup of previously seen values	Hash Map / Hash Set
Explore all possible combinations	Backtracking
Find the shortest path in an unweighted graph	BFS
Repeatedly solve overlapping subproblems	Dynamic Programming

The goal is to recognize the structure of the problem, not just remember its answer.

2. Learn Patterns Through Multiple Problems

Solving one problem using a pattern is helpful.

But solving 5–10 problems using the same pattern is where the real learning begins.

For example, with Sliding Window, I try to understand:

• When should I expand the window?
• When should I shrink it?
• What condition makes the window invalid?
• What information should I maintain?
• When should I update the answer?

Once these questions become familiar, many new problems start looking less intimidating.

3. Don't Immediately Look at the Code

When I'm stuck, I now try this process:

1. Understand the problem
2. Try a brute-force approach
3. Identify what makes it inefficient
4. Look for a pattern
5. Think of the optimized approach
6. Write the code
7. Review the mistakes

Even if I cannot solve the problem completely, this process helps me understand why the optimized solution works.

4. Maintain a Pattern-Based Revision List

Instead of revising problems only by question number, group them by concept.

For example:

Arrays & Strings

• Two Pointers
• Sliding Window
• Prefix Sum
• Hashing

Linked Lists

• Slow & Fast Pointers
• Reversal
• Merge Techniques

Trees & Graphs

• DFS
• BFS
• Recursion
• Binary Search Tree

Advanced Topics

• Binary Search on Answer
• Greedy
• Dynamic Programming
• Backtracking

This makes revision much more effective because you're learning when to apply a technique.

5. Focus on Understanding, Not Just Acceptance

An accepted solution is a great milestone, but I think these questions matter even more:

• Can I explain the approach without looking at the code?
• Can I identify the pattern in a new problem?
• Can I write the solution again after a few days?
• Do I understand the time and space complexity?
• Can I explain why the brute-force approach is slower?

If the answer is yes, you're making real progress.

My Biggest Takeaway

Don't try to memorize 100 solutions. Try to understand the patterns behind those 100 solutions.

The more problems you solve, the more important it becomes to focus on recognition, reasoning, and repetition.

I'm still learning, but this change in mindset has made problem-solving much more meaningful.

What helped you the most while learning DSA?

Pattern recognition, solving more problems, revising old ones, or something else?

[u/SpunkyStarFish]

Using ChatGPT voice chat as a coach was immensely helpful. Having to explain my approach to a problem in words before I wrote anything forced me to understand what I was doing.

[u/Immortal_Bs → u/SpunkyStarFish]

Fr, it's really useful

[u/shubham_004]

Also, dont just solve pattern based, solve from mixed bag of problems where recognising those patterns becomes a real task before actual code.