- easy
- okay
- hard
- [1] Contains Duplicate
- [1] Valid Anagram
- [1] Two Sum
- [1] Group Anagrams
- Top K Frequent Elements
- [2] Product of Array Except Self
- Valid Sudoku
- Encode And Decode Strings
- Longest Consecutive Sequence
- [1] Valid Palindrome
- [1] Two Sum II Input Array Is Sorted
- [3] 3Sum
- [2] Container With Most Water
- Trapping Rain Water
- [2] Best Time to Buy And Sell Stock
- [2] Longest Substring Without Repeating Characters
- [2] Longest Repeating Character Replacement
- Permutation In String
- Minimum Window Substring
- Sliding Window Maximum
- [2] Valid Parentheses
- [2] Min Stack
- Evaluate Reverse Polish Notation
- Generate Parentheses
- Daily Temperatures
- Car Fleet
- Largest Rectangle In Histogram
- [2] Binary Search
- [2] Search a 2D Matrix
- [2] Koko Eating Bananas
- [2] Search In Rotated Sorted Array
- Find Minimum In Rotated Sorted Array
- Time Based Key Value Store
- Median of Two Sorted Arrays
- [2] Reverse Linked List
- [1] Merge Two Sorted Lists
- Reorder List
- Remove Nth Node From End of List
- Copy List With Random Pointer
- Add Two Numbers
- [2] Linked List Cycle
- [1] Find The Duplicate Number
- LRU Cache
- Merge K Sorted Lists
- Reverse Nodes In K Group
- [2] Invert Binary Tree
- [2] Maximum Depth of Binary Tree
- Diameter of Binary Tree
- [2] Balanced Binary Tree
- Same Tree
- Subtree of Another Tree
- Lowest Common Ancestor of a Binary Search Tree
- Binary Tree Level Order Traversal
- Binary Tree Right Side View
- Count Good Nodes In Binary Tree
- Validate Binary Search Tree
- Kth Smallest Element In a Bst
- Construct Binary Tree From Preorder And Inorder Traversal
- Binary Tree Maximum Path Sum
- Serialize And Deserialize Binary Tree
- Implement Trie Prefix Tree
- Design Add And Search Words Data Structure
- Word Search II
- Kth Largest Element In a Stream
- Last Stone Weight
- K Closest Points to Origin
- Kth Largest Element In An Array
- Task Scheduler
- Design Twitter
- Find Median From Data Stream
- Subsets
- Combination Sum
- Permutations
- Subsets II
- Combination Sum II
- Word Search
- Palindrome Partitioning
- Letter Combinations of a Phone Number
- N Queens
- Number of Islands
- Clone Graph
- Max Area of Island
- Pacific Atlantic Water Flow
- Surrounded Regions
- Rotting Oranges
- Walls And Gates
- Course Schedule
- Course Schedule II
- Redundant Connection
- Number of Connected Components In An Undirected Graph
- Graph Valid Tree
- Word Ladder
- Reconstruct Itinerary
- Min Cost to Connect All Points
- Network Delay Time
- Swim In Rising Water
- Alien Dictionary
- Cheapest Flights Within K Stops
- Climbing Stairs
- Min Cost Climbing Stairs
- House Robber
- House Robber II
- Longest Palindromic Substring
- Palindromic Substrings
- Decode Ways
- Coin Change
- Maximum Product Subarray
- Word Break
- Longest Increasing Subsequence
- Partition Equal Subset Sum
- Unique Paths
- Longest Common Subsequence
- Best Time to Buy And Sell Stock With Cooldown
- Coin Change II
- Target Sum
- Interleaving String
- Longest Increasing Path In a Matrix
- Distinct Subsequences
- Edit Distance
- Burst Balloons
- Regular Expression Matching
- Maximum Subarray
- Jump Game
- Jump Game II
- Gas Station
- Hand of Straights
- Merge Triplets to Form Target Triplet
- Partition Labels
- Valid Parenthesis String
- Insert Interval
- Merge Intervals
- Non Overlapping Intervals
- Meeting Rooms
- Meeting Rooms II
- Minimum Interval to Include Each Query
- Rotate Image
- Spiral Matrix
- Set Matrix Zeroes
- Happy Number
- Plus One
- Pow(x, n)
- Multiply Strings
- Detect Squares
- Single Number
- Number of 1 Bits
- Counting Bits
- Reverse Bits
- Missing Number
- Sum of Two Integers
- Reverse Integer