Arrays & Hashing
- 0217.Contains Duplicate - Easy
- 0242.Valid Anagram - Easy
- 0001.Two Sum - Easy
- 0049.Group Anagrams - Medium
- 0347.Top K Frequent Elements - Medium
- 0271.Encode and Decode Strings - Medium
- 0238.Product of Array Except Self - Medium
- 0036.Valid Sudoku - Medium
- 0128.Longest Consecutive Sequence - Medium
Two Pointers
- 0125.Valid Palindrome - Easy
- 0167.Two Sum II - Medium
- 0015.3Sum - Medium
- 0011.Container w Most Water - Medium
- 0042.Trapping Rain Water - Hard
Sliding Window
- 0121.Best Time to Buy and Sell Stock - Easy
- 0003.Longest Substring wo Repeating Characters - Medium
- 0424.Longest Repeating Character Replacement - Medium
- 0567.Permutation in String
Stack
- 0020.Valid Parentheses - Easy
- 0155.Min Stack - Medium
Binary Search
- 0704.Binary_Search - Easy
- 0875.Koko Eating Bananas - Medium
Linked List
- 0206.Reverse Linked List - Easy
- 0146.LRU Cache - Medium
Trees
Heap / Priority Queue
- 0215.Kth Largest Element in an Array - Medium
Backtracking
- 0022.Generate Parentheses - Medium
Tries
Graphs
- 0200.Number of Islands - Medium
- 0695.Max Area of Island - Medium
- 0994.Rotting Oranges - Medium
- 0207.Course Schedule - Medium
Advanced Graphs
1-D Dynamic Programming
- 0198.House Robber - Medium
2-D Dynamic Programming
Greedy
Intervals
- 0057.Insert Interval - Medium
- 0056.Merge Intervals - Medium
Math & Geometry
- 0048.Rotate Image - Medium