Getting Started with LeetCode

Why LeetCode?

LeetCode is one of the best platforms for sharpening your problem-solving skills. Here’s how I approach it.

My Strategy

1. Start with the fundamentals — arrays, strings, hash maps
2. Learn the patterns — sliding window, two pointers, BFS/DFS
3. Practice consistently — aim for at least one problem a day
4. Review and reflect — understand why a solution works, not just how

A Simple Example

Here’s a classic two-sum solution in Python:

def two_sum(nums: list[int], target: int) -> list[int]:
    seen = {}
    for i, num in enumerate(nums):
        complement = target - num
        if complement in seen:
            return [seen[complement], i]
        seen[num] = i
    return []

The key insight is using a hash map to achieve O(n) time complexity instead of the naive O(n^2) brute force approach.

Recommended Topics

• Arrays & Hashing — foundation of most problems
• Two Pointers — efficient traversal techniques
• Binary Search — divide and conquer
• Dynamic Programming — breaking problems into subproblems
• Graphs — BFS, DFS, topological sort

Keep practicing, and the patterns will become second nature.