Up to date (2018-7-8), there are 833 Algorithms questions on LeetCode Online Judge.
The number of questions is increasing continually.
Here are the Solutions of some of these questions.
I'll keep updating for full summary and better Solution & Analysis.
Stay tuned for updates.
| Title | Bug free | Difficulty | Tags | Solution & Analysis & Note |
|---|---|---|---|---|
| 1.Two Sum | 3/24/2018 |
Easy | Array Hash Table |
c++ |
| 4.Median of Two Sorted Arrays | 9/7/2018 ★☆☆ |
Hard | Array Binary Search Divided and Conquer |
c++ |
| 11.Container With Most Water | 6/3/2018 |
Medium | Array Two Pointers |
c++ |
| 16.3Sum Closest | 3/26/2018 |
Medium | Array Two Pointers |
c++ |
| 17.Letter Combinations of a Phone Number | 7/21/2018 |
Medium | String Backtracking |
c++ |
| 18.4Sum | 5/23/2018 |
Medium | Array Hash Table Two Pointers |
c++ |
| 19. Remove Nth Node From End of List | 7/14/2018 |
Medium | Link List Two Pointers |
c++ |
| 20. Valid Parentheses | 7/22/2018 |
Easy | String Stack |
c++ |
| 21. Merge Two Sorted Lists | 10/7/2018 ★★★ |
Easy | Link List |
c++ |
| 22. Generate Parentheses | 9/7/2018 ★★☆ |
Medium | Backtracking String |
c++ |
| 26.Remove Duplicates from Sorted Array | 7/10/2018 |
Easy | Array |
c++ |
| 28.Implement strStr() | 6/8/2018 |
Easy | Two Pointers string |
c++ |
| 29.Divide Two Integers | ★☆☆ |
Medium | Math Binary Search |
c++ |
| 33.Search in Rotated Sorted Array | 8/23/2018 |
Medium | Array Binary Search |
c++ |
| 31.Next Permutation | ★☆☆ |
Medium | Array |
c++ |
| 34.Find First and Last Position of Element in Sorted Array | 8/29/2018 |
Medium | Array Binary Search |
c++ |
| 35.Search Insert Position | 4/4/2018 |
Easy | Array Binary Search |
c++ |
| 36. Valid Sudoku | 7/30/2018 |
Medium | Hash Table |
c++ |
| 37. Sudoku Solver | 7/30/2018 |
Hard | Hash Table Backtracking |
c++ |
| 38.Count and Say | 8/8/2018 |
Easy | String |
c++ |
| 39.Combination Sum | 7/21/2018 |
Medium | Array Backtracking |
c++ |
| 40.Combination Sum II | 6/26/2018 |
Medium | Array Backtracking |
c++ |
| 41.First Missing Positive | 5/20/2018 ★☆☆ |
Hard | Array |
c++ |
| 42.Trapping Rain Water | 6/3/2018 ★☆☆ |
Hard | Array Two Pointers stack |
c++ |
| 45.Jump Game II | 5/3/2018 ★☆☆ |
Hard | Array Greedy |
c++ |
| 46. Permutations | 7/21/2018 |
Medium | Backtracking |
c++ |
| 47. Permutations II | 6/26/2018 ★☆☆ |
Medium | Backtracking |
c++ |
| 48.Rotate Image | 10/6/2018 |
Medium | Array |
c++ |
| 49. Group Anagrams | 8/8/2018 ★☆☆ |
Medium | String Hash Table |
c++ |
| 50. Pow(x, n) | ★☆☆ |
Medium | Math Binary Search |
c++ |
| 52.N-Queens II | 7/23/2018 ★☆☆ |
Hard | Backtracking |
c++ |
| 53. Maximum Subarray | 8/2/2018 |
Easy | Array Devide and Conquer Dynamic Programming |
c++ |
| 54.Spiral Matrix | 6/26/2018 |
Medium | Array |
c++ |
| 55.Jump Game | 5/2/2018 |
Medium | Array Greedy |
c++ |
| 56.Merge Intervals | 10/7/2018 ★☆☆ |
Medium | Array Sort |
c++ |
| 57.Insert Interval | ★☆☆ |
Medium | Array Sort |
c++ |
| 59.Spiral Matrix II | 6/2/2018 ★☆☆ |
Medium | Array |
c++ |
| 60.Permutation Sequence | 6/19/2018 ★☆☆ |
Medium | Math Backtracking |
c++ |
| 61.Rotate List | 7/15/2018 |
Medium | Link List Two Points |
c++ |
| 62.Unique Paths | 8/30/2018 |
Medium | Array Dynamic Programming |
c++ |
| 63.Unique Paths II | 8/30/2018 |
Medium | Array Dynamic Programming |
c++ |
| 64. Minimum Path Sum | ★★☆ |
Medium | Array Dynamic Programming |
c++ |
| 66.Plus One | ★★☆ |
Easy | Array Math |
c++ |
| 69.Sqrt(x) | 11/7/2018 |
Easy | Math Binary Search |
c++ |
| 72.Edit Distance | 5/3/2018 |
Hard | String Dynamic Programming |
c++ |
| 73.Set Matrix Zeroes | 10/6/2018 |
Medium | Array |
c++ |
| 74.Search a 2D Matrix | 8/30/2018 |
Medium | Array Binary Search |
c++ |
| 75.Sort Colors | 8/23/2018 |
Medium | Sort Two Points Array |
c++ |
| 78. Subsets | 6/12/2018 |
Medium | Array Backtracking Bit Manipulation |
c++ |
| 79.Word Search | 10/5/2018 ★☆☆ |
Medium | Array Backtracking |
c++ |
| 80.Remove Duplicates from Sorted Array II | ★☆☆ |
Medium | Array Two Pointers |
c++ |
| 81. Search in Rotated Sorted Array II | 9/6/2018 ★☆☆ |
Medium | Array Binary Search |
c++ |
| 83. Remove Duplicates from Sorted List | 7/14/2018 |
Easy | Link List |
c++ |
| 88.Merge Sorted Array | 9/6/2018 ★☆☆ |
Easy | Array Two Pointers |
c++ |
| 90. Subsets II | 7/14/2018 |
Medium | Array Backtracking |
c++ |
| 92.Reverse Linked List II | 7/14/2018 ★☆☆ |
Medium | Linked List |
c++ |
| 93.Restore IP Addresses | 6/28/2018 |
Medium | String Backtracking |
c++ |
| 94.Binary Tree Inorder Traversal | 5/17/1018 |
Medium | Hash Table Stack Tree |
c++ |
| 98. Validate Binary Search Tree | 10/6/2018 |
Medium | Tree Depth-first Search |
c++ |
| 101.Symmetric Tree | 10/6/2018 |
Easy | Tree Depth-first Search Breadth-first Search |
c++ |
| 102. Binary Tree Level Order Traversal | 3/9/2018 |
Medium | Tree Breadth-first Search |
c++ |
| 103. Binary Tree Zigzag Level Order Traversal | 10/6/2018 |
Medium | Tree Stack Breadth-first Search |
c++ |
| 104. Maximum Depth of Binary Tree | 3/10/2018 |
Easy | Tree Depth-first Search |
c++ |
| 105.Construct Binary Tree from Preorder and Inorder Traversal | 8/5/2018 ★☆☆ |
Medium | Array Depth-first Search Tree |
c++ |
| 106.Construct Binary Tree from Inorder and Postorder Traversal | 10/6/2018 ★☆☆ |
Medium | Array Depth-first Search Tree |
c++ |
| 107. Binary Tree Level Order Traversal II | 3/9/2018 |
Easy | Tree Breadth-first Search |
c++ |
| 110. Balanced Binary Tree | 3/10/2018 ★☆☆ |
Easy | Tree Depth-first Search |
c++ |
| 111. Minimum Depth of Binary Tree | 5/21/2018 ★☆☆ |
Easy | Tree Depth-first Search Breadth-first Search |
c++ |
| 112. Path Sum | 10/6/2018 |
Easy | Tree Depth-first Search |
c++ |
| 118. Pascal's Triangle | 7/9/2018 |
Easy | Array |
c++ |
| 119.Pascal's Triangle II | ★★☆ |
Easy | Array |
c++ |
| 120.Triangle | 9/6/2018 ★☆☆ |
Medium | Array Dynamic Programming |
c++ |
| 121. Best Time to Buy and Sell Stock | 7/8/2018 |
Easy | Array Dynamic Programming |
c++ |
| 122. Best Time to Buy and Sell Stock II | 7/20/2018 |
Easy | Array Greedy |
c++ |
| 123. Best Time to Buy and Sell Stock III | 8/3/2018 |
Hard | Array Dynamic Processing |
c++ |
| 124. Binary Tree Maximum Path Sum | 10/6/2018 ★☆☆ |
Hard | Tree Depth-first Search |
c++ |
| 127. Remove Element | 7/9/2018 |
Easy | Array Two Pointers |
c++ |
| 129. Sum Root to Leaf Numbers | 3/21/2018 |
Medium | Tree Depth-first Search |
c++ |
| 131. Palindrome Partitioning | 6/28/2018 |
Medium | Backtracking |
c++ |
| 132. Palindrome Partitioning II | 9/2/2018 ★☆☆ |
Hard | Dynamic Programing |
c++ |
| 133. Clone Graph | × |
Medium | Depth-first Search Breadth-first Search Graph |
c++ |
| 138. Copy List with Random Pointer | 7/27/2018 |
Medium | Link List Hash Table |
c++ |
| 141. Linked List Cycle | 9/4/2018 |
Easy | Link List Two Point |
c++ |
| 142. Linked List Cycle II | 9/4/2018 |
Medium | Link List Two Point |
c++ |
| 143. Reorder List | 9/4/2018 |
Medium | Link List |
c++ |
| 144.Binary Tree Preorder Traversal | 5/17/2018 |
Medium | Stack Tree |
c++ |
| 145.Binary Tree Postorder Traversal | 5/20/2018 |
Hard | Stack Tree |
c++ |
| 146.LRU Cache | 7/29/2018 ★★★ |
Hard | Design |
c++ |
| 147.Insertion Sort List | 7/16/2018 ★★☆ |
Medium | Link List |
c++ |
| 148.Sort List | 7/28/2016 ★★☆ |
Medium | Link List Sort |
c++ |
| 151. Reverse Words in a String | 8/8/2018 |
Medium | String |
c++ |
| 153.Find Minimum in Rotated Sorted Array | 9/4/2018 |
Medium | Array Binary Search |
c++ |
| 154.Find Minimum in Rotated Sorted Array II | 9/6/2018 ★☆☆ |
Hard | Array Binary Search |
c++ |
| 160.Intersection of Two Linked Lists | 7/16/2018 |
Easy | Link List |
c++ |
| 161. One Edit Distance | 8/13/2018 |
Medium | String |
c++ |
| 162.Find Peak Element | 9/5/2018 |
Medium | Array Binary Search |
c++ |
| 165. Compare Version Numbers | 11/7/2018 |
Medium | String |
c++ |
| 167.Two Sum II - Input array is sorted | 5/22/2018 |
Easy | Array Two Pointers Binary-search Tree |
c++ |
| 169. Majority Element | 9/5/2018 ★★☆ |
Easy | Array Devide and Conquer Bit manipulation |
c++ |
| 174.Dungeon Game | 9/6/2018 ★☆☆ |
Hard | Binary-search Tree Dynamic Programming |
c++ |
| 186. Reverse Words in a String II | 8/22/2018 |
Medium | String |
c++ |
| 188.Best Time to Buy and Sell Stock IV | 8/4/2018 |
Hard | Dynamic Processing |
c++ |
| 189.Rotate Array | 9/6/2018 |
Easy | Array |
c++ |
| 198.House Robber | 8/5/2018 |
Easy | Dynamic Processing |
c++ |
| 206.Reverse Linked List | 5/21/2018 |
Easy | Linked List |
c++ |
| 209.Minimum Size Subarray Sum | 9/6/2018 ★☆☆ |
Easy | Array Two Point Binary Search |
c++ |
| 213.House Robber II | 8/5/2018 |
Medium | Dynamic Processing |
c++ |
| 216.Combination Sum III | 6/20/2018 |
Medium | Array Backtracking |
c++ |
| 217. Contains Duplicate | 7/8/2018 |
Easy | Array Hash Table |
c++ |
| 219.Contains Duplicate II | 9/6/2018 |
Easy | Array Hash Table |
c++ |
| 220. Contains Duplicate III | 9/6/2018 ★☆☆ |
Medium | Binary Search |
c++ |
| 222.Count Complete Tree Nodes | 9/6/2018 ★★☆ |
Medium | Binary Search Tree |
c++ |
| 229.Majority Element II | 9/5/2018 ★☆☆ |
Medium | Array |
c++ |
| 230.Kth Smallest Element in a BST | 9/13/2018 ★★★ |
Medium | Binary Search Tree |
c++ |
| 235.Lowest Common Ancestor of a Binary Search Tree | 8/7/2018 ★☆☆ |
Easy | Tree |
c++ |
| 236.Lowest Common Ancestor of a Binary Tree | 10/6/2018 |
Medium | Tree |
c++ |
| 238.Product of Array Except Self | 6/3/2018 |
Medium | Array |
c++ |
| 238. Product of Array Except Self | 7/12/2018 |
Medium | Array |
c++ |
| 240.Search a 2D Matrix II | 9/13/2018 ★☆☆ |
Medium | Binary Search Divide and Conquer |
c++ |
| 252.Meeting Rooms | 9/14/2018 |
Easy | Sort |
c++ |
| 253.Meeting Rooms II | 9/19/2018 ★☆☆ |
Medium | Sort Heap Greedy |
c++ |
| 266. Palindrome Permutation | 8/13/2018 |
Easy | Hash Table |
c++ |
| 268. Missing Number | 9/19/2018 ★☆☆ |
Easy | Array Math Bit manipulation |
c++ |
| 270. Closest Binary Search Tree Value | 10/6/2018 |
Easy | Tree Binary Search |
c++ |
| 272. Closest Binary Search Tree Value II | 9/20/2018 |
Hard | Tree Stack |
c++ |
| 274.H-Index | 9/20/2018 |
Medium | Hash Table Sort |
c++ |
| 275.H-Index II | 9/21/2018 ★☆☆ |
Medium | Binary Search |
c++ |
| 277. Find the Celebrity | 9/21/2018 |
Medium | Array |
c++ |
| 278.First Bad Version | 9/21/2018 |
Easy | Binary Search |
c++ |
| 283. Move Zeroes | 9/21/2018 |
Easy | Array Two Pointers |
c++ |
| 285. Inorder Successor in BST | 10/6/2018 ★☆☆ |
Medium | Tree |
c++ |
| 287.Find the Duplicate Number | 9/21/2018 |
Medium | Array Two Pointers Binary Search |
c++ |
| 300.Longest Increasing Subsequence | 9/21/2018 ★☆☆ |
Medium | Binary Search Dynamic Programming |
c++ |
| 301.Remove Invalid Parentheses | /9/24/2018 ★☆☆ |
Medium | Depth-first Search Breadth-first Search |
c++ |
| 309.Best Time to Buy and Sell Stock with Cooldown | 9/24/2018 ★☆☆ |
Medium | Dynamic Processing |
c++ |
| 339. Nested List Weight Sum | 9/25/2018 |
Easy | Depth-first Search |
c++ |
| 346. Moving Average from Data Stream | 9/25/2018 |
Medium | Design Queue |
c++ |
| 348.Design Tic-Tac-Toe | 9/25/2018 |
Medium | Design |
c++ |
| 349.Intersection of Two Arrays | 8/28/2018 |
Easy | Hash Table Two Pointers Binary Search Sort |
c++ |
| 350.Intersection of Two Arrays II | 9/26/2018 |
Easy | Hash Table Two Pointers Binary Search Sort |
c++ |
| 354.Russian Doll Envelopes | 9/26/2018 |
Hard | Binary Search Dynamic Programming |
c++ |
| 363.Max Sum of Rectangle No Larger Than K | 10/2/2018 |
Hard | Binary Search Dynamic Programming Queue |
c++ |
| 364. Nested List Weight Sum II | 10/2/2018 |
Medium | Depth-first Search |
c++ |
| 367.Valid Perfect Square | 10/2/2018 |
Easy | Math Binary Search |
c++ |
| 374.Guess Number Higher or Lower | 10/2/2018 |
Easy | Binary Search |
c++ |
| 377.Combination Sum IV | 10/2/2018 ★☆☆ |
Medium | Dynamic Programming |
c++ |
| 378.Kth Smallest Element in a Sorted Matrix | 10/2/2018 ★☆☆ |
Medium | Binary Search Heap |
c++ |
| 392.Is Subsequence | 10/2/2018 ★☆☆ |
Medium | Binary Search Dynamic Programming Greedy |
c++ |
| 407.Trapping Rain Water II | ✖ | Hard | Array Breadth-first Search |
c++ |
| 410. Split Array Largest Sum | 10/3/2018 ★☆☆ |
Hard | Binary Search Dynamic Programming |
c++ |
| 414.Third Maximum Number | 10/2/2018 ★★★ |
Easy | Array |
c++ |
| 441. Arranging Coins | 10/2/2018 ★☆☆ |
Easy | Math Binary Search |
c++ |
| 436. Find Right Interval | ignore |
Medium | Binary Search |
c++ |
| 442. Find All Duplicates in an Array | 10/3/2018 |
Medium | Array |
c++ |
| 448. Find All Numbers Disappeared in an Array | 10/3/2018 |
Easy | Array |
c++ |
| 454.4Sum II | 10/3/2018 |
Medium | Hash Table Binary Search |
c++ |
| 473. Matchsticks to Square | 10/3/2018 ★☆☆ |
Medium | Depth-first Search |
c++ |
| 475.Heaters | 10/3/2018 ★☆☆ |
Easy | Binary Search |
c++ |
| 483.Smallest Good Base | hard | Binary Search |
c++ | |
| 485. Max Consecutive Ones | 10/3/2018 |
Easy | Array |
c++ |
| 495. Teemo Attacking | 10/3/2018 |
Medium | Array |
c++ |
| 501. Find Mode in Binary Search Tree | 10/3/2018 |
Easy | Tree |
c++ |
| 532.K-diff Pairs in an Array | 10/3/2018 ★☆☆ |
Easy | Array Hash Table Two Pointers |
c++ |
| 543.Diameter of Binary Tree | 8/8/2018 |
Easy | Tree |
c++ |
| 560.Subarray Sum Equals K | 10/3/2018 ★☆☆ |
Medium | Array Hash Table |
c++ |
| 561. Array Partition I | ★☆☆ |
Easy | Array |
c++ |
| 565.Array Nesting | 10/3/2018 ★☆☆ |
Medium | Array |
c++ |
| 566. Reshape the Matrix | ★☆☆ |
Easy | Array |
c++ |
| 567. Permutation in String | 10/4/2018 ★☆☆ |
Medium | Two Pointers |
c++ |
| 581.Shortest Unsorted Continuous Subarray | 10/4/2018 ★☆☆ |
Easy | Array |
c++ |
| 605. Can Place Flowers | 10/4/2018 |
Easy | Array |
c++ |
| 611.Valid Triangle Number | 10/4/2018 ★☆☆ |
Medium | Array Binary Search Tow Pointers |
c++ |
| 621.Task Scheduler | 10/4/2018 ★☆☆ |
Medium | Array Queue Greedy |
c++ |
| 628.Maximum Product of Three Numbers | 10/4/2018 ★☆☆ |
Easy | Array |
c++ |
| 643.Maximum Average Subarray I | 10/4/2018 |
Easy | Array |
c++ |
| 653.Two Sum IV - Input is a BST | 8/6/2018 |
Easy | Tree |
c++ |
| 661. Image Smoother | 10/3/2018 |
Easy | Array |
c++ |
| 658. Find K Closest Elements | 10/4/2018 ★☆☆ |
Medium | Binary Search |
c++ |
| 665.Non-decreasing Array | 10/4/2018 ★☆☆ |
Easy | Array |
c++ |
| 667. Beautiful Arrangement II | 10/4/2018 ★☆☆ |
Medium | Array |
c++ |
| 668. Kth Smallest Number in Multiplication Table | Hard | Binary Search |
c++ | |
| 674.Longest Continuous Increasing Subsequence | 10/4/2018 |
Easy | Array |
c++ |
| 681. Next Closest Time | ignore |
Medium | String |
c++ |
| 683. K Empty Slots | ★☆☆ |
Hard | Array Binary Search Tree |
c++ |
| 687. Longest Univalue Path | 10/4/2018 ★☆☆ |
Easy | Tree Recursion |
c++ |
| 695. Max Area of Island | 10/4/2018 ★☆☆ |
Easy | Array Depth-first search |
c++ |
| 697. Degree of an Array | 10/4/2018 ★☆☆ |
Easy | Array |
c++ |
| 713.Subarray Product Less Than K | 10/4/2018 ★☆☆ |
Medium | Array Two Points |
c++ |
| 714.Best Time to Buy and Sell Stock with Transaction Fee | ★☆☆ |
Medium | Array Greedy Dynamic Programming |
c++ |
| 717. 1-bit and 2-bit Characters | 10/5/2018 ★☆☆ |
Easy | Array |
c++ |
| 718. Maximum Length of Repeated Subarray | 10/5/2018 ★☆☆ |
Medium | Array Hash Table Binary Search Dynamic Programming |
c++ |
| 719. Find K-th Smallest Pair Distance | Hard | Array Binary Search Heap |
c++ | |
| 724. Find Pivot Index | 10/5/2018 ★☆☆ |
Easy | Array |
c++ |
| 729.My Calendar I | 10/5/2018 ★☆☆ |
Medium | Array |
c++ |
| 744. Find Smallest Letter Greater Than Target | 10/5/2018 |
Easy | Binary Search |
c++ |
| 746. Min Cost Climbing Stairs | 10/5/2018 |
Easy | Array Dynamic Programming |
c++ |
| 747. Largest Number At Least Twice of Others | 10/5/2018 |
Easy | Array |
c++ |
| 766. Toeplitz Matrix | 10/5/2018 |
Easy | Array |
c++ |
| 769. Max Chunks To Make Sorted | 10/5/2018 ★☆☆ |
Medium | Array |
c++ |
| 775.Global and Local Inversions | 10/5/2018 ★☆☆ |
Medium | Array Math |
c++ |
| 778. Swim in Rising Water | Hard | Binary Search Heap Depth-first Search Union Find |
c++ | |
| 786. K-th Smallest Prime Fraction | Hard | Binary Search Heap |
c++ | |
| 792.Number of Matching Subsequences | 10/5/2018 ★☆☆ |
Medium | Array |
c++ |
| 793. K-th Smallest Prime Fraction | Hard | Binary Search |
c++ | |
| 825.Friends Of Appropriate Ages | 10/5/2018 |
Medium | Array |
c++ |
| 830. Positions of Large Groups | 7/8/2018 |
Easy | Array |
c++ |
| 832.Flipping an Image | 7/8/2018 |
Easy | Array |
c++ |
| 840.Magic Squares In Grid | 7/10/2018 |
Easy | Array |
c++ |
| 849.Maximize Distance to Closest Person | 7/10/2018 |
Easy | Array |
c++ |
| 852. Peak Index in a Mountain Array | 10/5/2018 |
Easy | Binary Search |
c++ |
| 868. Transpose Matrix | 7/8/2018 |
Easy | Array |
c++ |
| 402. Remove K Digits | 8/20/2018 |
Medium | Stack Greedy |
c++ |
| 273.Integer to English Words | 8/21/2018 |
Hard | String Math |
c++ |
| 171. Excel Sheet Column Number | 8/21/2018 |
Easy | Math |
c++ |
| 223. Rectangle Area | 8/21/2018 |
Medium | Math |
c++ |
| 658. Find K Closest Elements | 8/21/2018 |
Medium | Binary Search |
c++ |
| 232. Implement Queue using Stacks | 8/21/2018 |
Easy | Stack Design |
c++ |
| 116. Populating Next Right Pointers in Each Node | 8/21/2018 |
Medium | Tree Depth-first Search |
c++ |
| 191. Number of 1 Bits | 8/21/2018 |
Easy | Bit Manipulation |
c++ |
| 237.Delete Node in a Linked List | 8/22/2018 |
Medium | Linked List |
c++ |
| 10. Regular Expression Matching | × |
Hard | Backtracking String Dynamic Programming |
c++ |
| 695.Max Area of Island | 8/23/2018 |
Easy | Array Depth-first Search |
c++ |
| 415.Add Strings | 8/23/2018 |
Easy | Math |
c++ |
| 445.Add Two Numbers II | 8/27/2018 |
Medium | Linked List Math |
c++ |
| 43 | ★☆☆ |
Medium | `` | c++ |
| 212. Word Search II | 10/5/2018 ★☆☆ |
Hard | BackTracking Trie |
c++ |
| 2.Add Two Numbers | 8/27/2018 |
Medium | Linked List Math |
c++ |
| 525. Contiguous Array | 8/27/2018 |
Medium | Hash Table |
c++ |
| 187. Repeated DNA Sequences | 8/28/2018 |
Medium | Hash Table Bit Manipulation |
c++ |
| 347.Top K Frequent Elements | 8/28/2018 |
Medium | Hash Table Heap |
c++ |
| 200.Number of Islands | 10/5/2018 ★☆☆ |
Medium | Depth-first Search Breadth-first Search Union Find |
c++ |
| 305. Number of Islands II | 9/17/2018 ☆☆☆ |
Hard | Union Find |
c++ |
| 208. Implement Trie (Prefix Tree) | 10/6/2018 ☆☆☆ |
Medium | Trie Design |
c++ |
| 297. Serialize and Deserialize Binary Tree | 10/6/2018 ☆☆☆ |
Hard | Tree Design |
c++ |
| 173. Binary Search Tree Iterator | 10/6/2018 ☆☆☆ |
Medium | Tree Design Stack |
c++ |
| 117. Populating Next Right Pointers in Each Node II | 10/6/2018 ☆☆☆ |
Hard | Binary Search Tree |
c++ |
| 114. Flatten Binary Tree to Linked List | 10.6.2018 ☆☆☆ |
Medium | Tree Depth-first Search |
c++ |
| 24. Swap Nodes in Pairs | 10/6/2018 ★☆☆ |
Medium | Linked List |
c++ |
| 23. Merge k Sorted Lists | 10/7/2018 ★☆☆ |
Hard | Linked List Divide and Conquer Heap |
c++ |
| 25. Reverse Nodes in k-Group | 10/7/2018 ★☆☆ |
Hard | Linked List |
c++ |
| 71. Simplify Path | ignore |
Medium | Stack String |
c++ |
| 5. Longest Palindromic Substring | 10/7/2018 ★☆☆ |
Medium | Dynamic Programming String |
c++ |
| 91. Decode Ways | 10/7/2018 ★☆☆ |
Medium | Dynamic Programming String |
c++ |
| 125. Valid Palindrome | ignore |
Easy | Two Pointers String |
c++ |
| 8. String to Integer (atoi) | ignore |
Medium | String Math |
c++ |
| 215.Kth Largest Element in an Array | 10/7/2018 ★☆☆ |
Medium | Heap Divide and Conquer |
c++ |
| 168.Excel Sheet Column Title | 10/7/2018 ★☆☆ |
Medium | Math |
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| 258.Add Digits | 10/7/2018 ★☆☆ |
Medium | Math |
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| 207. Course Schedule | 10/7/2018 ★☆☆ |
Medium | Depth-first Search Breadth-first Search Graph Topological Sort |
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| 692.Top K Frequent Words | 10/7/2018 ★☆☆ |
Medium | Hash Table Heap Trie |
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| 328.Odd Even Linked List | 10/7/2018 |
Medium | Linked List |
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| 329.Longest Increasing Path in a Matrix | 10/7/2018 ★☆☆ |
Hard | Depth-first Search Topological Sort Memoization |
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| 284. Peeking Iterator | 11/7/2018 ★☆☆ |
Medium | Design |
c++ |
| 7. Reverse Integer | 11/7/2018 ★☆☆ |
Easy | Math |
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| 221. Maximal Square | 11/7/2018 ★☆☆ |
Medium | Dynamic Programming |
c++ |
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Medium | |
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Medium | |
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Medium | |
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