@Zen_with_AI: The key to improving efficiency in brushing LeetCode is essentially pattern recognition. When you get a new problem, do…

The key to improving efficiency in brushing LeetCode is essentially pattern recognition. When you get a new problem, don't blindly brute-force enumerate; instead, complete abstraction within 30 seconds: Seeing "maximum/minimum of a contiguous subarray" --> associate with sliding window; Seeing "Top K problems" --> directly lock onto heap/priority queue; Seeing "shortest path in a graph" --> instantly apply BFS template. Algorithm interviews aren't about competing on impromptu inspiration, but on proficiency in feature extraction and code templates. Break down common data structures and algorithm patterns thoroughly, and you'll naturally match the optimal solution instantly when you see a problem. ---- 🚀 Suggestion: Bookmark this! NeetCode 150 complete brushing list + pattern classification quick reference Brushing problems isn't about quantity but quality—master these 150 classic problems by pattern classification, and the core essence of improving on LeetCode is "pattern recognition." When you see a problem's requirements, you'll be able to abstract the corresponding data structure and algorithm template in seconds, and the interview is basically locked in! Below is the NeetCode 150's 15 core categories and complete problem list to help you start your pattern recognition training: --- 📌 1. Array & Hashing (Arrays and Hashing) - 9 problems 1. Contains Duplicate 2. Valid Anagram 3. Two Sum 4. Group Anagrams 5. Top K Frequent Elements 6. Product of Array Except Self 7. Valid Sudoku 8. Encode and Decode Strings 9. Longest Consecutive Sequence --- 📌 2. Two Pointers (Two Pointers) - 5 problems 1. Valid Palindrome 2. Two Sum II Input Array Is Sorted 3. 3Sum 4. Container With Most Water 5. Trapping Rain Water --- 📌 3. Sliding Window (Sliding Window) - 6 problems 1. Best Time to Buy And Sell Stock 2. Longest Substring Without Repeating Characters 3. Longest Repeating Character Replacement 4. Permutation In String 5. Minimum Window Substring 6. Sliding Window Maximum --- 📌 4. Stack (Stack) - 7 problems 1. Valid Parentheses 2. Min Stack 3. Evaluate Reverse Polish Notation 4. Generate Parentheses 5. Daily Temperatures 6. Car Fleet 7. Largest Rectangle In Histogram --- 📌 5. Binary Search (Binary Search) - 7 problems 1. Binary Search 2. Search a 2D Matrix 3. Koko Eating Bananas 4. Find Minimum In Rotated Sorted Array 5. Search In Rotated Sorted Array 6. Time Based Key-Value Store 7. Median of Two Sorted Arrays --- 📌 6. Linked List (Linked List) - 11 problems 1. Reverse Linked List 2. Merge Two Sorted Lists 3. Reorder List 4. Remove Nth Node From End of List 5. Copy List With Random Pointer 6. Add Two Numbers 7. Linked List Cycle 8. Find The Duplicate Number 9. LRU Cache 10. Merge K Sorted Lists 11. Reverse Nodes In K-Group --- 📌 7. Trees (Binary Trees) - 15 problems 1. Invert Binary Tree 2. Maximum Depth of Binary Tree 3. Diameter of Binary Tree 4. Balanced Binary Tree 5. Same Tree 6. Subtree of Another Tree 7. Lowest Common Ancestor of a BST 8. Binary Tree Level Order Traversal 9. Binary Tree Right Side View 10. Count Good Nodes In Binary Tree 11. Validate Binary Search Tree 12. Kth Smallest Element In a BST 13. Construct Binary Tree From Preorder And Inorder Traversal 14. Binary Tree Maximum Path Sum 15. Serialize And Deserialize Binary Tree --- 📌 8. Tries (Tries) - 3 problems 1. Implement Trie Prefix Tree 2. Design Add And Search Words Data Structure 3. Word Search II --- 📌 9. Heap / Priority Queue (Heap / Priority Queue) - 7 problems 1. Kth Largest Element In a Stream 2. Last Stone Weight 3. K Closest Points to Origin 4. Kth Largest Element In An Array 5. Task Scheduler 6. Design Twitter 7. Find Median From Data Stream --- 📌 10. Backtracking (Backtracking) - 9 problems 1. Subsets 2. Combination Sum 3. Permutations 4. Subsets II 5. Combination Sum II 6. Word Search 7. Palette Partitioning 8. Letter Combinations of a Phone Number 9. N-Queens --- 📌 11. Graphs (Graphs) - 13 problems 1. Number of Islands 2. Max Area of Island 3. Clone Graph 4. Walls And Gates 5. Rotting Oranges 6. Pacific Atlantic Water Flow 7. Surrounded Regions 8. Course Schedule 9. Course Schedule II 10. Graph Valid Tree 11. Number of Connected Components In An Undirected Graph 12. Redundant Connection 13. Word Ladder --- 📌 12. Advanced Graphs (Advanced Graphs) - 6 problems 1. Reconstruct Itinerary 2. Min Cost to Connect All Points 3. Network Delay Time 4. Swim In Rising Water 5. Alien Dictionary 6. Cheapest Flights Within K Stops --- 📌 13. 1D Dynamic Programming (1D Dynamic Programming) - 12 problems 1. Climbing Stairs 2. Min Cost Climbing Stairs 3. House Robber 4. House Robber II 5. Longest Palindromic Substring 6. Palindromic Substrings 7. Decode Ways 8. Coin Change 9. Maximum Product Subarray 10. Word Break 11. Longest Increasing Subsequence 12. Partition Equal Subset Sum --- 📌 14. 2D Dynamic Programming (2D Dynamic Programming) - 11 problems 1. Unique Paths 2. Longest Common Subsequence 3. Best Time to Buy And Sell Stock With Cooldown 4. Coin Change II 5. Target Sum 6. Interleaving String 7. Longest Increasing Path In a Matrix 8. Distinct Subsequences 9. Edit Distance 10. Burst Balloons 11. Regular Expression Matching --- 📌 15. Greedy, Intervals, Math & Bit Manipulation (Greedy/Intervals/Math & Bit Manipulation) - 29 problems • Greedy: 1. Maximum Subarray 2. Jump Game 3. Jump Game II 4. Gas Station 5. Hand of Straights 6. Merge Triplets to Form Target Triplet 7. Partition Labels 8. Valid Parenthesis String • Intervals: 9. Insert Interval 10. Merge Intervals 11. Non-Overlapping Intervals 12. Meeting Rooms 13. Meeting Rooms II 14. Minimum Interval to Include Each Query • Bit Manipulation: 15. Single Number 16. Number of 1 Bits 17. Counting Bits 18. Reverse Bits 19. Missing Number 20. Sum of Two Integers 21. Reverse Integer • Math & Geometry: 22. Rotate Image 23. Spiral Matrix 24. Set Matrix Zeroes 25. Happy Number 26. Pow(x, n) 27. Multiply Strings 28. Detect Squares