🧠 NeetCode / Blind 75 Problem Solving Notes

This is my personal record of solving problems from the famous Blind 75 list.
I organize them by topic for better focus and revision.

📚 Index

🧮 Array

Title Difficulty Tags Date
Two Sum Easy Hash Map  
Best Time to Buy and Sell Stock Easy Greedy  
Contains Duplicate Easy Set  
Product of Array Except Self Medium Array, Prefix  
Maximum Subarray Easy DP  
Maximum Product Subarray Medium DP  
Find Minimum in Rotated Sorted Array Medium Binary Search  
Search in Rotated Sorted Array Medium Binary Search  
3Sum Medium Two Pointers  
Container With Most Water Medium Two Pointers  

💡 Binary

Title Difficulty Tags Date
Sum of Two Integers Medium Bit Manipulation  
Number of 1 Bits Easy Bit Manipulation  
Counting Bits Easy DP  
Missing Number Easy Bit Manipulation, Math  
Reverse Bits Easy Bit Manipulation  

📈 Dynamic Programming

Title Difficulty Tags Date
Climbing Stairs Easy DP  
Coin Change Medium DP  
Longest Increasing Subsequence Medium DP  
Longest Common Subsequence Medium DP  
Word Break Medium DP, Trie  
Combination Sum Medium Backtracking  
House Robber Easy DP  
House Robber II Medium DP  
Decode Ways Medium DP  
Unique Paths Medium DP  
Jump Game Medium Greedy, DP  

🔗 Graph

Title Difficulty Tags Date
Clone Graph Medium DFS, BFS  
Course Schedule Medium Topological Sort  
Pacific Atlantic Water Flow Medium DFS, BFS  
Number of Islands Medium DFS, BFS  
Longest Consecutive Sequence Medium Hash Set  
Alien Dictionary Hard Topological Sort  
Graph Valid Tree Medium Union Find  
Number of Connected Components in an Undirected Graph Medium DFS, Union Find  

🗓️ Interval

Title Difficulty Tags Date
Insert Interval Medium Sorting  
Merge Intervals Medium Sorting  
Non-overlapping Intervals Medium Greedy  
Meeting Rooms Easy Interval  
Meeting Rooms II Medium Heap  

🔗 Linked List

Title Difficulty Tags Date
Reverse a Linked List Easy Linked List  
Detect Cycle in a Linked List Medium Two Pointers  
Merge Two Sorted Lists Easy Linked List  
Merge K Sorted Lists Hard Heap  
Remove Nth Node From End Of List Medium Two Pointers  
Reorder List Medium Two Pointers  

🧮 Matrix

Title Difficulty Tags Date
Set Matrix Zeroes Medium Matrix  
Spiral Matrix Medium Matrix  
Rotate Image Medium Matrix  
Word Search Medium DFS  

🔤 String

Title Difficulty Tags Date
Longest Substring Without Repeating Characters Medium Sliding Window  
Longest Repeating Character Replacement Medium Sliding Window  
Minimum Window Substring Hard Sliding Window  
Valid Anagram Easy Hash Map  
Group Anagrams Medium Hash Map  
Valid Parentheses Easy Stack  
Valid Palindrome Easy Two Pointers  
Longest Palindromic Substring Medium DP  
Palindromic Substrings Medium DP  
Encode and Decode Strings Medium Design  

🌳 Tree / Trie

Title Difficulty Tags Date
Maximum Depth of Binary Tree Easy DFS  
Same Tree Easy DFS  
Invert Binary Tree Easy DFS  
Binary Tree Maximum Path Sum Hard DFS  
Binary Tree Level Order Traversal Medium BFS 2025.07.24
Serialize and Deserialize Binary Tree Hard DFS, BFS  
Subtree of Another Tree Easy DFS  
Construct Binary Tree from Preorder and Inorder Traversal Medium DFS  
Validate Binary Search Tree Medium DFS 2025.07.30
Kth Smallest Element in a BST Medium DFS  
Lowest Common Ancestor in BST Medium BST 2025.06.19
Implement Trie (Prefix Tree) Medium Trie  
Add and Search Word Medium Trie  
Word Search II Hard Trie, DFS  

🧺 Heap / Priority Queue

Title Difficulty Tags Date
Merge K Sorted Lists Hard Heap  
Top K Frequent Elements Medium Heap  
Find Median from Data Stream Hard Heap, Design  

你可以：

  1. Which topics are most important? If you have limited time, here are the most important topics to focus on:

Arrays Hash Maps Trees Graphs