- Range DP (2)
- String (23)
- Math (16)
- DP (55)
- Double Sequence DP (3)
- BFS (11)
- Segment Tree (1)
- Design (8)
- DFS (29)
- Game Theory (4)
- Hash Table (19)
- Backtracking (11)
- Sort (6)
- Tree (20)
- Trie (7)
- BST (16)
- Permutation (1)
- Partition DP (4)
- Heap (6)
- Interval DP (1)
- Stack (12)
- Linked List (8)
- Binary Indexed Tree (1)
- Graph (5)
- Brainteaser (1)
- Union Find (7)
- Sweep Line (4)
- Interval (1)
- Sequence DP (12)
- Bitwise DP (1)
- MiniMax (1)
- Two Pointers (15)
- Basic Implementation (2)
- Backpack DP (3)
- Bit Manipulation (9)
- Divide and Conquer (5)
- Status DP (1)
- Topological Sort (4)
- Greedy (7)
- Hash Map (1)
- Coordinate DP (10)
- Monotonous Stack (1)
- Binary Tree (2)
- Binary Search (24)
- Array (45)
- Memoization (7)
- Two Stacks (1)
- backtracking (1)
- Two Pointer (1)
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Scramble String.java | Hard | Java | [DP, Range DP, String] | |
| 1 | Burst Balloons.java | Hard | Java | [DP, Divide and Conquer, Memoization, Range DP] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Judge Route Circle.java | Easy | Java | [String] | |
| 1 | First Unique Character in a String.java | Easy | Java | [Hash Table, String] | |
| 2 | Reverse Vowels of a String.java | Easy | Java | [String, Two Pointers] | |
| 3 | Scramble String.java | Hard | Java | [DP, Range DP, String] | |
| 4 | Interleaving String.java | Hard | Java | [DP, String] | |
| 5 | Letter Combinations of a Phone Number.java | Medium | Java | [Backtracking, String] | |
| 6 | Edit Distance.java | Hard | Java | [DP, Double Sequence DP, String] | |
| 7 | Distinct Subsequences.java | Hard | Java | [DP, String] | |
| 8 | Regular Expression Matching.java | Review | Java | [Backtracking, DP, String] | |
| 9 | Wildcard Matching.java | Hard | Java | [Backtracking, DP, Greedy, String] | |
| 10 | Add Binary.java | Easy | Java | [Math, String] | |
| 11 | Longest Substring Without Repeating Characters.java | Medium | Java | [Hash Table, String, Two Pointers] | |
| 12 | Minimum Window Substring.java | Hard | Java | [Hash Table, String, Two Pointers] | |
| 13 | Longest Substring with At Most K Distinct Characters.java | Medium | Java | [Hash Table, String] | |
| 14 | Palindrome Pairs.java | Hard | Java | [Hash Table, String, Trie] | |
| 15 | Change to Anagram.java | Easy | Java | [String] | |
| 16 | Compare Version Numbers.java | Medium | Java | [String] | |
| 17 | Compare Strings.java | Easy | Java | [String] | |
| 18 | Count and Say.java | Easy | Java | [Basic Implementation, String] | |
| 19 | One Edit Distance.java | Medium | Java | [String] | |
| 20 | Decode Ways.java | Medium | Java | [DP, Partition DP, String] | |
| 21 | Group Anagrams.java | Medium | Java | [Hash Map, String] | |
| 22 | Flip Game.java | Easy | Java | [String] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Power of Three.java | Easy | Java | [Math] | |
| 1 | Plus One.java | Easy | Java | [Array, Math] | |
| 2 | Power of Two.java | Easy | Java | [Bit Manipulation, Math] | |
| 3 | Encode and Decode TinyURL.java | Medium | Java | [Hash Table, Math] | |
| 4 | Perfect Squares.java | Medium | Java | [BFS, DP, Math, Partition DP] | |
| 5 | Valid Perfect Square.java | Review | Java | [Binary Search, Math] | |
| 6 | Pow(x,n).java | Medium | Java | [Binary Search, Math] | |
| 7 | Add Binary.java | Easy | Java | [Math, String] | |
| 8 | Add Digits.java | Easy | Java | [Math] | |
| 9 | Add Two Numbers.java | Medium | Java | [Linked List, Math] | |
| 10 | Reverse Integer.java | Easy | Java | [Math] | |
| 11 | Sqrt(x).java | Easy | Java | [Binary Search, Math] | |
| 12 | Continuous Subarray Sum.java | Medium | Java | [Coordinate DP, DP, Math] | |
| 13 | Count Primes.java | Easy | Java | [Hash Table, Math] | |
| 14 | Excel Sheet Column Number.java | Easy | Java | [Math] | |
| 15 | Excel Sheet Column Title.java | Easy | Java | [Math] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Coin Change.java | Medium | Java | [DP, Memoization, Sequence DP] | |
| 1 | Maximum Product Subarray.java | Medium | Java | [Array, DP] | |
| 2 | k Sum.java | Hard | Java | [DP] | |
| 3 | Longest Increasing Subsequence.java | Medium | Java | [Binary Search, Coordinate DP, DP, Memoization, Sequence DP] | |
| 4 | Unique Binary Search Tree.java | Medium | Java | [BST, DP, Tree] | |
| 5 | Unique Paths II.java | Medium | Java | [Array, Coordinate DP, DP] | |
| 6 | Bomb Enemy.java | Medium | Java | [Coordinate DP, DP] | |
| 7 | Perfect Squares.java | Medium | Java | [BFS, DP, Math, Partition DP] | |
| 8 | Backpack VI.java | Medium | Java | [DP] | |
| 9 | Copy Books.java | Hard | Java | [Binary Search, DP, Partition DP] | |
| 10 | Backpack III.java | Review | Java | [DP] | |
| 11 | Longest Palindromic Subsequence.java | Medium | Java | [DP] | |
| 12 | Scramble String.java | Hard | Java | [DP, Range DP, String] | |
| 13 | Best Time to Buy and Sell Stock with Cooldown.java | Medium | Java | [DP] | |
| 14 | Longest Common Subsequence.java | Medium | Java | [DP, Double Sequence DP] | |
| 15 | Interleaving String.java | Hard | Java | [DP, String] | |
| 16 | Edit Distance.java | Hard | Java | [DP, Double Sequence DP, String] | |
| 17 | Distinct Subsequences.java | Hard | Java | [DP, String] | |
| 18 | Regular Expression Matching.java | Review | Java | [Backtracking, DP, String] | |
| 19 | Wildcard Matching.java | Hard | Java | [Backtracking, DP, Greedy, String] | |
| 20 | Ones and Zeroes.java | Hard | Java | [DP] | |
| 21 | Word Break II.java | Review | Java | [Backtracking, DP] | |
| 22 | Unique Path.java | Medium | Java | [Array, Coordinate DP, DP] | |
| 23 | Maximal Rectangle.java | Hard | Java | [Array, DP, Hash Table, Stack] | |
| 24 | Maximal Square.java | Medium | Java | [Coordinate DP, DP] | |
| 25 | Longest Increasing Path in a Matrix.java | Hard | Java | [DFS, DP, Memoization, Topological Sort] | |
| 26 | Coins in a Line.java | Medium | Java | [DP, Game Theory, Greedy] | |
| 27 | Coins in a Line II.java | Medium | Java | [Array, DP, Game Theory, Memoization, MiniMax] | |
| 28 | Climbing Stairs.java | Easy | Java | [DP, Memoization, Sequence DP] | |
| 29 | Coins in a Line III.java | Hard | Java | [Array, DP, Game Theory, Interval DP, Memoization] | |
| 30 | Burst Balloons.java | Hard | Java | [DP, Divide and Conquer, Memoization, Range DP] | |
| 31 | Nim Game.java | Easy | Java | [Brainteaser, DP, Game Theory] | |
| 32 | K Edit Distance.java | Hard | Java | [DP, Double Sequence DP, Trie] | |
| 33 | Jump Game.java | Medium | Java | [Array, DP, Greedy] | |
| 34 | Coin Change 2.java | Medium | Java | [DP, Sequence DP] | |
| 35 | Paint House.java | Easy | Java | [DP, Sequence DP] | |
| 36 | Decode Ways.java | Medium | Java | [DP, Partition DP, String] | |
| 37 | Longest Continuous Increasing Subsequence.java | Easy | Java | [Array, Coordinate DP, DP] | |
| 38 | Minimum Path Sum.java | Medium | Java | [Array, Coordinate DP, DP] | |
| 39 | Counting Bits.java | Medium | Java | [Bit Manipulation, Bitwise DP, DP] | |
| 40 | Continuous Subarray Sum.java | Medium | Java | [Coordinate DP, DP, Math] | |
| 41 | House Robber.java | Easy | Java | [DP, Sequence DP] | |
| 42 | House Robber II.java | Medium | Java | [DP, Sequence DP] | |
| 43 | House Robber III.java | Medium | Java | [DFS, DP, Status DP, Tree] | |
| 44 | Paint House II.java | Hard | Java | [DP, Sequence DP] | |
| 45 | Best Time to Buy and Sell Stock I.java | Easy | Java | [Array, DP, Sequence DP] | |
| 46 | Best Time to Buy and Sell Stock II.java | Easy | Java | [Array, DP, Greedy, Sequence DP] | |
| 47 | Best Time to Buy and Sell Stock III .java | Hard | Java | [Array, DP, Sequence DP] | |
| 48 | Best Time to Buy and Sell Stock IV.java | Hard | Java | [DP, Sequence DP] | |
| 49 | Russian Doll Envelopes.java | Hard | Java | [Binary Search, Coordinate DP, DP] | |
| 50 | Jump Game II.java | Hard | Java | [Array, Coordinate DP, DP, Greedy] | |
| 51 | Palindrome Partitioning II.java | Hard | Java | [DP, Partition DP] | |
| 52 | Backpack.java | Medium | Java | [Backpack DP, DP] | |
| 53 | Backpack II.java | Medium | Java | [Backpack DP, DP] | |
| 54 | Backpack V.java | Medium | Java | [Backpack DP, DP] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Longest Common Subsequence.java | Medium | Java | [DP, Double Sequence DP] | |
| 1 | Edit Distance.java | Hard | Java | [DP, Double Sequence DP, String] | |
| 2 | K Edit Distance.java | Hard | Java | [DP, Double Sequence DP, Trie] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Perfect Squares.java | Medium | Java | [BFS, DP, Math, Partition DP] | |
| 1 | Clone Graph.java | Medium | Java | [BFS, DFS, Graph] | |
| 2 | Number of Islands.java | Medium | Java | [BFS, DFS, Union Find] | |
| 3 | Graph Valid Tree.java | Medium | Java | [BFS, DFS, Graph, Union Find] | |
| 4 | Surrounded Regions.java | Review | Java | [BFS, DFS, Union Find] | |
| 5 | Trapping Rain Water II.java | Hard | Java | [BFS, Heap] | |
| 6 | Course Schedule.java | Medium | Java | [BFS, DFS, Graph, Topological Sort] | |
| 7 | Course Schedule II.java | Medium | Java | [BFS, DFS, Graph, Topological Sort] | |
| 8 | Alien Dictionary.java | Hard | Java | [BFS, Backtracking, DFS, Graph, Topological Sort] | |
| 9 | Binary Tree Preorder Traversal.java | Easy | Java | [BFS, DFS, Stack, Tree] | |
| 10 | Complete Binary Tree.java | Easy | Java | [BFS, DFS, Tree] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Building Outline.java | Review | Java | [Binary Indexed Tree, Divide and Conquer, Heap, Segment Tree, Sweep Line] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Binary Search Tree Iterator.java | Medium | Java | [BST, Design, Stack, Tree] | |
| 1 | Flatten Nested List Iterator.java | Medium | Java | [Design, Stack] | |
| 2 | Implement Trie.java | Medium | Java | [Design, Trie] | |
| 3 | Add and Search Word.java | Medium | Java | [Backtracking, Design, Trie] | |
| 4 | Data Stream Median.java | Hard | Java | [Design, Heap] | |
| 5 | Sliding Window Median.java | Hard | Java | [Design, Heap] | |
| 6 | Min Stack.java | Easy | Java | [Design, Stack] | |
| 7 | Implement Queue using Stacks.java | Easy | Java | [Design, Stack] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Nested List Weight Sum.java | Easy | Java | [DFS] | |
| 1 | Same Tree.java | Easy | Java | [DFS, Tree] | |
| 2 | Convert Sorted Array to Binary Search Tree.java | Easy | Java | [DFS, Tree] | |
| 3 | Binary Tree Maximum Path Sum.java | Review | Java | [DFS, Tree] | |
| 4 | Construct Binary Tree from Inorder and Preorder Traversal.java | Medium | Java | [Array, DFS, Tree] | |
| 5 | Path Sum.java | Easy | Java | [DFS, Tree] | |
| 6 | Balanced Binary Tree.java | Medium | Java | [DFS, Tree] | |
| 7 | Populating Next Right Pointers in Each Node.java | Medium | Java | [DFS, Tree] | |
| 8 | Validate Binary Search Tree.java | Medium | Java | [BST, DFS, Tree] | |
| 9 | Convert Sorted List to Binary Search Tree.java | Medium | Java | [DFS, Linked List] | |
| 10 | Flatten Binary Tree to Linked List.java | Medium | Java | [Binary Tree, DFS] | |
| 11 | Binary Tree Paths.java | Easy | Java | [Binary Tree, DFS] | |
| 12 | Clone Graph.java | Medium | Java | [BFS, DFS, Graph] | |
| 13 | Number of Islands.java | Medium | Java | [BFS, DFS, Union Find] | |
| 14 | Graph Valid Tree.java | Medium | Java | [BFS, DFS, Graph, Union Find] | |
| 15 | Surrounded Regions.java | Review | Java | [BFS, DFS, Union Find] | |
| 16 | Word Search II.java | Hard | Java | [Backtracking, DFS, Trie] | |
| 17 | Expression Expand.java | Medium | Java | [DFS, Divide and Conquer, Stack] | |
| 18 | Find Peak Element II.java | Hard | Java | [Binary Search, DFS, Divide and Conquer] | |
| 19 | Longest Increasing Path in a Matrix.java | Hard | Java | [DFS, DP, Memoization, Topological Sort] | |
| 20 | Path Sum II.java | Easy | Java | [DFS, Tree] | |
| 21 | Course Schedule.java | Medium | Java | [BFS, DFS, Graph, Topological Sort] | |
| 22 | Course Schedule II.java | Medium | Java | [BFS, DFS, Graph, Topological Sort] | |
| 23 | Alien Dictionary.java | Hard | Java | [BFS, Backtracking, DFS, Graph, Topological Sort] | |
| 24 | Binary Tree Preorder Traversal.java | Easy | Java | [BFS, DFS, Stack, Tree] | |
| 25 | Complete Binary Tree.java | Easy | Java | [BFS, DFS, Tree] | |
| 26 | House Robber III.java | Medium | Java | [DFS, DP, Status DP, Tree] | |
| 27 | Palindrome Partitioning.java | Medium | Java | [Backtracking, DFS] | |
| 28 | Flip Game II.java | Review | Java | [DFS, backtracking] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Coins in a Line.java | Medium | Java | [DP, Game Theory, Greedy] | |
| 1 | Coins in a Line II.java | Medium | Java | [Array, DP, Game Theory, Memoization, MiniMax] | |
| 2 | Coins in a Line III.java | Hard | Java | [Array, DP, Game Theory, Interval DP, Memoization] | |
| 3 | Nim Game.java | Easy | Java | [Brainteaser, DP, Game Theory] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Jewels and Stones.java | Easy | Java | [Hash Table] | |
| 1 | Find Anagram Mappings.java | Easy | Java | [Hash Table] | |
| 2 | Island Perimeter.java | Easy | Java | [Hash Table] | |
| 3 | First Unique Character in a String.java | Easy | Java | [Hash Table, String] | |
| 4 | Encode and Decode TinyURL.java | Medium | Java | [Hash Table, Math] | |
| 5 | 2 Sum.java | Easy | Java | [Array, Hash Table] | |
| 6 | 4 Sum.java | Medium | Java | [Hash Table] | |
| 7 | Intersection of Two Arrays II.java | Easy | Java | [Binary Search, Hash Table, Sort, Two Pointers] | |
| 8 | Valid Anagram.java | Easy | Java | [Hash Table, Sort] | |
| 9 | Longest Substring Without Repeating Characters.java | Medium | Java | [Hash Table, String, Two Pointers] | |
| 10 | Minimum Window Substring.java | Hard | Java | [Hash Table, String, Two Pointers] | |
| 11 | Longest Substring with At Most K Distinct Characters.java | Medium | Java | [Hash Table, String] | |
| 12 | Palindrome Pairs.java | Hard | Java | [Hash Table, String, Trie] | |
| 13 | Maximal Rectangle.java | Hard | Java | [Array, DP, Hash Table, Stack] | |
| 14 | Binary Tree Inorder Traversal.java | Easy | Java | [Hash Table, Stack, Tree] | |
| 15 | Contains Duplicate.java | Easy | Java | [Array, Hash Table] | |
| 16 | Contains Duplicate II.java | Easy | Java | [Array, Hash Table] | |
| 17 | Find All Anagrams in a String.java | Easy | Java | [Hash Table] | |
| 18 | Count Primes.java | Easy | Java | [Hash Table, Math] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Letter Combinations of a Phone Number.java | Medium | Java | [Backtracking, String] | |
| 1 | Regular Expression Matching.java | Review | Java | [Backtracking, DP, String] | |
| 2 | Wildcard Matching.java | Hard | Java | [Backtracking, DP, Greedy, String] | |
| 3 | Word Break II.java | Review | Java | [Backtracking, DP] | |
| 4 | Add and Search Word.java | Medium | Java | [Backtracking, Design, Trie] | |
| 5 | Word Search II.java | Hard | Java | [Backtracking, DFS, Trie] | |
| 6 | Word Search.java | Medium | Java | [Array, Backtracking] | |
| 7 | Word Squares.java | Hard | Java | [Backtracking, Trie] | |
| 8 | Alien Dictionary.java | Hard | Java | [BFS, Backtracking, DFS, Graph, Topological Sort] | |
| 9 | Palindrome Partitioning.java | Medium | Java | [Backtracking, DFS] | |
| 10 | Permutations II.java | Medium | Java | [Backtracking] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Wiggle Sort.java | Medium | Java | [Array, Sort] | |
| 1 | Intersection of Two Arrays II.java | Easy | Java | [Binary Search, Hash Table, Sort, Two Pointers] | |
| 2 | Valid Anagram.java | Easy | Java | [Hash Table, Sort] | |
| 3 | Meeting Rooms.java | Easy | Java | [Sort, Sweep Line] | |
| 4 | Number of Airplane in the sky.java | Medium | Java | [Array, Interval, Sort, Sweep Line] | |
| 5 | Meeting Rooms II.java | Medium | Java | [Greedy, Heap, Sort, Sweep Line] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Unique Binary Search Tree.java | Medium | Java | [BST, DP, Tree] | |
| 1 | Trim a Binary Search Tree.java | Easy | Java | [BST, Tree] | |
| 2 | Binary Search Tree Iterator.java | Medium | Java | [BST, Design, Stack, Tree] | |
| 3 | Same Tree.java | Easy | Java | [DFS, Tree] | |
| 4 | Convert Sorted Array to Binary Search Tree.java | Easy | Java | [DFS, Tree] | |
| 5 | Binary Tree Maximum Path Sum.java | Review | Java | [DFS, Tree] | |
| 6 | Construct Binary Tree from Inorder and Preorder Traversal.java | Medium | Java | [Array, DFS, Tree] | |
| 7 | Path Sum.java | Easy | Java | [DFS, Tree] | |
| 8 | Balanced Binary Tree.java | Medium | Java | [DFS, Tree] | |
| 9 | Populating Next Right Pointers in Each Node.java | Medium | Java | [DFS, Tree] | |
| 10 | Validate Binary Search Tree.java | Medium | Java | [BST, DFS, Tree] | |
| 11 | Max Tree.java | Medium | Java | [Stack, Tree] | |
| 12 | Binary Tree Inorder Traversal.java | Easy | Java | [Hash Table, Stack, Tree] | |
| 13 | Path Sum II.java | Easy | Java | [DFS, Tree] | |
| 14 | Binary Tree Postorder Traversal.java | Medium | Java | [Stack, Tree, Two Stacks] | |
| 15 | Closest Binary Search Tree Value.java | Easy | Java | [BST, Binary Search, Tree] | |
| 16 | Count Complete Tree Nodes.java | Medium | Java | [Binary Search, Tree] | |
| 17 | Binary Tree Preorder Traversal.java | Easy | Java | [BFS, DFS, Stack, Tree] | |
| 18 | Complete Binary Tree.java | Easy | Java | [BFS, DFS, Tree] | |
| 19 | House Robber III.java | Medium | Java | [DFS, DP, Status DP, Tree] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Maximum XOR of Two Numbers in an Array.java | Medium | Java | [Bit Manipulation, Trie] | |
| 1 | Implement Trie.java | Medium | Java | [Design, Trie] | |
| 2 | Add and Search Word.java | Medium | Java | [Backtracking, Design, Trie] | |
| 3 | Word Search II.java | Hard | Java | [Backtracking, DFS, Trie] | |
| 4 | Word Squares.java | Hard | Java | [Backtracking, Trie] | |
| 5 | Palindrome Pairs.java | Hard | Java | [Hash Table, String, Trie] | |
| 6 | K Edit Distance.java | Hard | Java | [DP, Double Sequence DP, Trie] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Shuffle an Array.java | Medium | Java | [Permutation] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Perfect Squares.java | Medium | Java | [BFS, DP, Math, Partition DP] | |
| 1 | Copy Books.java | Hard | Java | [Binary Search, DP, Partition DP] | |
| 2 | Decode Ways.java | Medium | Java | [DP, Partition DP, String] | |
| 3 | Palindrome Partitioning II.java | Hard | Java | [DP, Partition DP] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Kth Smallest Number in Sorted Matrix.java | Medium | Java | [Binary Search, Heap] | |
| 1 | Trapping Rain Water II.java | Hard | Java | [BFS, Heap] | |
| 2 | Data Stream Median.java | Hard | Java | [Design, Heap] | |
| 3 | Sliding Window Median.java | Hard | Java | [Design, Heap] | |
| 4 | Meeting Rooms II.java | Medium | Java | [Greedy, Heap, Sort, Sweep Line] | |
| 5 | Building Outline.java | Review | Java | [Binary Indexed Tree, Divide and Conquer, Heap, Segment Tree, Sweep Line] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Coins in a Line III.java | Hard | Java | [Array, DP, Game Theory, Interval DP, Memoization] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Binary Search Tree Iterator.java | Medium | Java | [BST, Design, Stack, Tree] | |
| 1 | Flatten Nested List Iterator.java | Medium | Java | [Design, Stack] | |
| 2 | Trapping Rain Water.java | Hard | Java | [Array, Stack, Two Pointers] | |
| 3 | Min Stack.java | Easy | Java | [Design, Stack] | |
| 4 | Implement Queue using Stacks.java | Easy | Java | [Design, Stack] | |
| 5 | Expression Expand.java | Medium | Java | [DFS, Divide and Conquer, Stack] | |
| 6 | Largest Rectangle in Histogram.java | Hard | Java | [Array, Monotonous Stack, Stack] | |
| 7 | Max Tree.java | Medium | Java | [Stack, Tree] | |
| 8 | Maximal Rectangle.java | Hard | Java | [Array, DP, Hash Table, Stack] | |
| 9 | Binary Tree Inorder Traversal.java | Easy | Java | [Hash Table, Stack, Tree] | |
| 10 | Binary Tree Postorder Traversal.java | Medium | Java | [Stack, Tree, Two Stacks] | |
| 11 | Binary Tree Preorder Traversal.java | Easy | Java | [BFS, DFS, Stack, Tree] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Add Two Numbers.java | Medium | Java | [Linked List, Math] | |
| 1 | Add Two Numbers II.java | Medium | Java | [Linked List] | |
| 2 | Convert Sorted List to Binary Search Tree.java | Medium | Java | [DFS, Linked List] | |
| 3 | Linked List Cycle.java | Easy | Java | [Linked List, Two Pointers] | |
| 4 | Remove Nth Node From End of List.java | Medium | Java | [Linked List, Two Pointers] | |
| 5 | Linked List Cycle II.java | Medium | Java | [Linked List, Two Pointers] | |
| 6 | Swap Nodes in Pairs.java | Medium | Java | [Linked List] | |
| 7 | Delete Node in a Linked List.java | Easy | Java | [Linked List] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Building Outline.java | Review | Java | [Binary Indexed Tree, Divide and Conquer, Heap, Segment Tree, Sweep Line] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Clone Graph.java | Medium | Java | [BFS, DFS, Graph] | |
| 1 | Graph Valid Tree.java | Medium | Java | [BFS, DFS, Graph, Union Find] | |
| 2 | Course Schedule.java | Medium | Java | [BFS, DFS, Graph, Topological Sort] | |
| 3 | Course Schedule II.java | Medium | Java | [BFS, DFS, Graph, Topological Sort] | |
| 4 | Alien Dictionary.java | Hard | Java | [BFS, Backtracking, DFS, Graph, Topological Sort] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Nim Game.java | Easy | Java | [Brainteaser, DP, Game Theory] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Connecting Graph.java | Medium | Java | [Union Find] | |
| 1 | Connecting Graph II.java | Medium | Java | [Union Find] | |
| 2 | Connecting Graph III.java | Medium | Java | [Union Find] | |
| 3 | Number of Islands.java | Medium | Java | [BFS, DFS, Union Find] | |
| 4 | Number of Islands II.java | Hard | Java | [Union Find] | |
| 5 | Graph Valid Tree.java | Medium | Java | [BFS, DFS, Graph, Union Find] | |
| 6 | Surrounded Regions.java | Review | Java | [BFS, DFS, Union Find] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Meeting Rooms.java | Easy | Java | [Sort, Sweep Line] | |
| 1 | Number of Airplane in the sky.java | Medium | Java | [Array, Interval, Sort, Sweep Line] | |
| 2 | Meeting Rooms II.java | Medium | Java | [Greedy, Heap, Sort, Sweep Line] | |
| 3 | Building Outline.java | Review | Java | [Binary Indexed Tree, Divide and Conquer, Heap, Segment Tree, Sweep Line] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Number of Airplane in the sky.java | Medium | Java | [Array, Interval, Sort, Sweep Line] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Coin Change.java | Medium | Java | [DP, Memoization, Sequence DP] | |
| 1 | Longest Increasing Subsequence.java | Medium | Java | [Binary Search, Coordinate DP, DP, Memoization, Sequence DP] | |
| 2 | Climbing Stairs.java | Easy | Java | [DP, Memoization, Sequence DP] | |
| 3 | Coin Change 2.java | Medium | Java | [DP, Sequence DP] | |
| 4 | Paint House.java | Easy | Java | [DP, Sequence DP] | |
| 5 | House Robber.java | Easy | Java | [DP, Sequence DP] | |
| 6 | House Robber II.java | Medium | Java | [DP, Sequence DP] | |
| 7 | Paint House II.java | Hard | Java | [DP, Sequence DP] | |
| 8 | Best Time to Buy and Sell Stock I.java | Easy | Java | [Array, DP, Sequence DP] | |
| 9 | Best Time to Buy and Sell Stock II.java | Easy | Java | [Array, DP, Greedy, Sequence DP] | |
| 10 | Best Time to Buy and Sell Stock III .java | Hard | Java | [Array, DP, Sequence DP] | |
| 11 | Best Time to Buy and Sell Stock IV.java | Hard | Java | [DP, Sequence DP] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Counting Bits.java | Medium | Java | [Bit Manipulation, Bitwise DP, DP] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Coins in a Line II.java | Medium | Java | [Array, DP, Game Theory, Memoization, MiniMax] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Reverse Vowels of a String.java | Easy | Java | [String, Two Pointers] | |
| 1 | 2 Sum II - Input array is sorted.java | Medium | Java | [Array, Binary Search, Two Pointers] | |
| 2 | 2 Sum II.java | Medium | Java | [Array, Binary Search, Two Pointers] | |
| 3 | 3 Sum Closest.java | Medium | Java | [Array, Two Pointers] | |
| 4 | 3 Sum.java | Medium | Java | [Array, Two Pointers] | |
| 5 | 3 Sum Smaller.java | Medium | Java | [Array, Two Pointers] | |
| 6 | Intersection of Two Arrays II.java | Easy | Java | [Binary Search, Hash Table, Sort, Two Pointers] | |
| 7 | Minimum Size Subarray Sum.java | Medium | Java | [Array, Binary Search, Two Pointers] | |
| 8 | Longest Substring Without Repeating Characters.java | Medium | Java | [Hash Table, String, Two Pointers] | |
| 9 | Minimum Window Substring.java | Hard | Java | [Hash Table, String, Two Pointers] | |
| 10 | Linked List Cycle.java | Easy | Java | [Linked List, Two Pointers] | |
| 11 | Remove Nth Node From End of List.java | Medium | Java | [Linked List, Two Pointers] | |
| 12 | Linked List Cycle II.java | Medium | Java | [Linked List, Two Pointers] | |
| 13 | Trapping Rain Water.java | Hard | Java | [Array, Stack, Two Pointers] | |
| 14 | Find the Duplicate Number.java | Medium | Java | [Array, Binary Search, Two Pointers] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Cosine Similarity.java | Easy | Java | [Basic Implementation] | |
| 1 | Count and Say.java | Easy | Java | [Basic Implementation, String] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Backpack.java | Medium | Java | [Backpack DP, DP] | |
| 1 | Backpack II.java | Medium | Java | [Backpack DP, DP] | |
| 2 | Backpack V.java | Medium | Java | [Backpack DP, DP] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Power of Two.java | Easy | Java | [Bit Manipulation, Math] | |
| 1 | Sum of Two Integers.java | Easy | Java | [Bit Manipulation] | |
| 2 | Swap Bits.java | Easy | Java | [Bit Manipulation] | |
| 3 | Update Bits.java | Medium | Java | [Bit Manipulation] | |
| 4 | Maximum XOR of Two Numbers in an Array.java | Medium | Java | [Bit Manipulation, Trie] | |
| 5 | Majority Element.java | Easy | Java | [Array, Bit Manipulation, Divide and Conquer] | |
| 6 | Convert Integer A to Integer B.java | Easy | Java | [Bit Manipulation] | |
| 7 | Count 1 in Binary.java | Easy | Java | [Bit Manipulation] | |
| 8 | Counting Bits.java | Medium | Java | [Bit Manipulation, Bitwise DP, DP] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Majority Element.java | Easy | Java | [Array, Bit Manipulation, Divide and Conquer] | |
| 1 | Expression Expand.java | Medium | Java | [DFS, Divide and Conquer, Stack] | |
| 2 | Find Peak Element II.java | Hard | Java | [Binary Search, DFS, Divide and Conquer] | |
| 3 | Building Outline.java | Review | Java | [Binary Indexed Tree, Divide and Conquer, Heap, Segment Tree, Sweep Line] | |
| 4 | Burst Balloons.java | Hard | Java | [DP, Divide and Conquer, Memoization, Range DP] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | House Robber III.java | Medium | Java | [DFS, DP, Status DP, Tree] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Longest Increasing Path in a Matrix.java | Hard | Java | [DFS, DP, Memoization, Topological Sort] | |
| 1 | Course Schedule.java | Medium | Java | [BFS, DFS, Graph, Topological Sort] | |
| 2 | Course Schedule II.java | Medium | Java | [BFS, DFS, Graph, Topological Sort] | |
| 3 | Alien Dictionary.java | Hard | Java | [BFS, Backtracking, DFS, Graph, Topological Sort] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Queue Reconstruction by Height.java | Medium | Java | [Greedy] | |
| 1 | Wildcard Matching.java | Hard | Java | [Backtracking, DP, Greedy, String] | |
| 2 | Meeting Rooms II.java | Medium | Java | [Greedy, Heap, Sort, Sweep Line] | |
| 3 | Coins in a Line.java | Medium | Java | [DP, Game Theory, Greedy] | |
| 4 | Jump Game.java | Medium | Java | [Array, DP, Greedy] | |
| 5 | Best Time to Buy and Sell Stock II.java | Easy | Java | [Array, DP, Greedy, Sequence DP] | |
| 6 | Jump Game II.java | Hard | Java | [Array, Coordinate DP, DP, Greedy] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Group Anagrams.java | Medium | Java | [Hash Map, String] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Longest Increasing Subsequence.java | Medium | Java | [Binary Search, Coordinate DP, DP, Memoization, Sequence DP] | |
| 1 | Unique Paths II.java | Medium | Java | [Array, Coordinate DP, DP] | |
| 2 | Bomb Enemy.java | Medium | Java | [Coordinate DP, DP] | |
| 3 | Unique Path.java | Medium | Java | [Array, Coordinate DP, DP] | |
| 4 | Maximal Square.java | Medium | Java | [Coordinate DP, DP] | |
| 5 | Longest Continuous Increasing Subsequence.java | Easy | Java | [Array, Coordinate DP, DP] | |
| 6 | Minimum Path Sum.java | Medium | Java | [Array, Coordinate DP, DP] | |
| 7 | Continuous Subarray Sum.java | Medium | Java | [Coordinate DP, DP, Math] | |
| 8 | Russian Doll Envelopes.java | Hard | Java | [Binary Search, Coordinate DP, DP] | |
| 9 | Jump Game II.java | Hard | Java | [Array, Coordinate DP, DP, Greedy] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Largest Rectangle in Histogram.java | Hard | Java | [Array, Monotonous Stack, Stack] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Flatten Binary Tree to Linked List.java | Medium | Java | [Binary Tree, DFS] | |
| 1 | Binary Tree Paths.java | Easy | Java | [Binary Tree, DFS] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Guess Number Higher or Lower.java | Easy | Java | [Binary Search] | |
| 1 | 2 Sum II - Input array is sorted.java | Medium | Java | [Array, Binary Search, Two Pointers] | |
| 2 | 2 Sum II.java | Medium | Java | [Array, Binary Search, Two Pointers] | |
| 3 | Longest Increasing Subsequence.java | Medium | Java | [Binary Search, Coordinate DP, DP, Memoization, Sequence DP] | |
| 4 | Copy Books.java | Hard | Java | [Binary Search, DP, Partition DP] | |
| 5 | Valid Perfect Square.java | Review | Java | [Binary Search, Math] | |
| 6 | Intersection of Two Arrays II.java | Easy | Java | [Binary Search, Hash Table, Sort, Two Pointers] | |
| 7 | Find Peak Element.java | Medium | Java | [Array, Binary Search] | |
| 8 | Pow(x,n).java | Medium | Java | [Binary Search, Math] | |
| 9 | Minimum Size Subarray Sum.java | Medium | Java | [Array, Binary Search, Two Pointers] | |
| 10 | Kth Smallest Number in Sorted Matrix.java | Medium | Java | [Binary Search, Heap] | |
| 11 | Find Minimum in Rotated Sorted Array.java | Medium | Java | [Array, Binary Search] | |
| 12 | Find Minimum in Rotated Sorted Array II.java | Hard | Java | [Array, Binary Search] | |
| 13 | Find Peak Element II.java | Hard | Java | [Binary Search, DFS, Divide and Conquer] | |
| 14 | Sqrt(x).java | Easy | Java | [Binary Search, Math] | |
| 15 | First Bad Version.java | Easy | Java | [Binary Search] | |
| 16 | Wood Cut.java | Medium | Java | [Binary Search] | |
| 17 | Find the Duplicate Number.java | Medium | Java | [Array, Binary Search, Two Pointers] | |
| 18 | Maximum Average Subarray II.java | Review | Java | [Array, Binary Search] | |
| 19 | Classical Binary Search.java | Easy | Java | [Binary Search] | |
| 20 | Closest Binary Search Tree Value.java | Easy | Java | [BST, Binary Search, Tree] | |
| 21 | Count Complete Tree Nodes.java | Medium | Java | [Binary Search, Tree] | |
| 22 | Closest Number in Sorted Array.java | Easy | Java | [Binary Search] | |
| 23 | Russian Doll Envelopes.java | Hard | Java | [Binary Search, Coordinate DP, DP] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Plus One.java | Easy | Java | [Array, Math] | |
| 1 | Wiggle Sort.java | Medium | Java | [Array, Sort] | |
| 2 | 2 Sum.java | Easy | Java | [Array, Hash Table] | |
| 3 | 2 Sum II - Input array is sorted.java | Medium | Java | [Array, Binary Search, Two Pointers] | |
| 4 | 2 Sum II.java | Medium | Java | [Array, Binary Search, Two Pointers] | |
| 5 | Maximum Product Subarray.java | Medium | Java | [Array, DP] | |
| 6 | 3 Sum Closest.java | Medium | Java | [Array, Two Pointers] | |
| 7 | Triangle Count.java | Medium | Java | [Array] | |
| 8 | 3 Sum.java | Medium | Java | [Array, Two Pointers] | |
| 9 | Unique Paths II.java | Medium | Java | [Array, Coordinate DP, DP] | |
| 10 | 3 Sum Smaller.java | Medium | Java | [Array, Two Pointers] | |
| 11 | Array Partition I.java | Easy | Java | [Array] | |
| 12 | 1-bit and 2-bit Characters.java | Easy | Java | [Array] | |
| 13 | Non-decreasing Array.java | Easy | Java | [Array] | |
| 14 | Max Consecutive Ones.java | Easy | Java | [Array] | |
| 15 | Find All Numbers Disappeared in an Array.java | Easy | Java | [Array] | |
| 16 | Maximum Average Subarray I.java | Easy | Java | [Array] | |
| 17 | Largest Number At Least Twice of Others.java | Easy | Java | [Array] | |
| 18 | Toeplitz Matrix.java | Easy | Java | [Array] | |
| 19 | Find Peak Element.java | Medium | Java | [Array, Binary Search] | |
| 20 | Majority Element.java | Easy | Java | [Array, Bit Manipulation, Divide and Conquer] | |
| 21 | Construct Binary Tree from Inorder and Preorder Traversal.java | Medium | Java | [Array, DFS, Tree] | |
| 22 | Minimum Size Subarray Sum.java | Medium | Java | [Array, Binary Search, Two Pointers] | |
| 23 | Find Minimum in Rotated Sorted Array.java | Medium | Java | [Array, Binary Search] | |
| 24 | Find Minimum in Rotated Sorted Array II.java | Hard | Java | [Array, Binary Search] | |
| 25 | Word Search.java | Medium | Java | [Array, Backtracking] | |
| 26 | Trapping Rain Water.java | Hard | Java | [Array, Stack, Two Pointers] | |
| 27 | Largest Rectangle in Histogram.java | Hard | Java | [Array, Monotonous Stack, Stack] | |
| 28 | Find the Duplicate Number.java | Medium | Java | [Array, Binary Search, Two Pointers] | |
| 29 | Game of Life.java | Medium | Java | [Array] | |
| 30 | Maximum Average Subarray II.java | Review | Java | [Array, Binary Search] | |
| 31 | Number of Airplane in the sky.java | Medium | Java | [Array, Interval, Sort, Sweep Line] | |
| 32 | Unique Path.java | Medium | Java | [Array, Coordinate DP, DP] | |
| 33 | Maximal Rectangle.java | Hard | Java | [Array, DP, Hash Table, Stack] | |
| 34 | Coins in a Line II.java | Medium | Java | [Array, DP, Game Theory, Memoization, MiniMax] | |
| 35 | Coins in a Line III.java | Hard | Java | [Array, DP, Game Theory, Interval DP, Memoization] | |
| 36 | Contains Duplicate.java | Easy | Java | [Array, Hash Table] | |
| 37 | Contains Duplicate II.java | Easy | Java | [Array, Hash Table] | |
| 38 | Jump Game.java | Medium | Java | [Array, DP, Greedy] | |
| 39 | Longest Continuous Increasing Subsequence.java | Easy | Java | [Array, Coordinate DP, DP] | |
| 40 | Minimum Path Sum.java | Medium | Java | [Array, Coordinate DP, DP] | |
| 41 | Best Time to Buy and Sell Stock I.java | Easy | Java | [Array, DP, Sequence DP] | |
| 42 | Best Time to Buy and Sell Stock II.java | Easy | Java | [Array, DP, Greedy, Sequence DP] | |
| 43 | Best Time to Buy and Sell Stock III .java | Hard | Java | [Array, DP, Sequence DP] | |
| 44 | Jump Game II.java | Hard | Java | [Array, Coordinate DP, DP, Greedy] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Coin Change.java | Medium | Java | [DP, Memoization, Sequence DP] | |
| 1 | Longest Increasing Subsequence.java | Medium | Java | [Binary Search, Coordinate DP, DP, Memoization, Sequence DP] | |
| 2 | Longest Increasing Path in a Matrix.java | Hard | Java | [DFS, DP, Memoization, Topological Sort] | |
| 3 | Coins in a Line II.java | Medium | Java | [Array, DP, Game Theory, Memoization, MiniMax] | |
| 4 | Climbing Stairs.java | Easy | Java | [DP, Memoization, Sequence DP] | |
| 5 | Coins in a Line III.java | Hard | Java | [Array, DP, Game Theory, Interval DP, Memoization] | |
| 6 | Burst Balloons.java | Hard | Java | [DP, Divide and Conquer, Memoization, Range DP] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Binary Tree Postorder Traversal.java | Medium | Java | [Stack, Tree, Two Stacks] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Flip Game II.java | Review | Java | [DFS, backtracking] |
| Squence | Problem | Level | Language | Tags | Video Tutorial |
|---|---|---|---|---|---|
| 0 | Permutation in String.java | Medium | Java | [Two Pointer] |