- E indicate Easy, M indicate Medium and H indicate Hard.
- "+" means need to redo.
- "-" means failed to solve.
- "?" means cannot understand the purpose of this problem.
- "^" means needing a faster solution.
- Arrays
- Recursion and Dynamic Programming
- Fast and Slow Pointers
- Stack and Queue
- Search and Sorting
- Trees and Graphs
| index | date | notes |
|---|---|---|
| 212.Contains Duplicate (E) | 2021-06-26 | |
| 268.Missing Number (E) | 2021-06-27 | + |
| 448.Find All Numbers Disappeared in an Array (E) | 2021-06-27 | run time error |
| 136. Single Number (E) | 2021-06-28 | |
| 344. Reverse String (E) | 2021-06-29 | in-place |
| 541. Reverse String II (E) | 2021-07-01 | + |
| 566. Reshape the Matrix (E) | 2021-07-11 | ^ |
| 66. Plus One (E) | 2021-07-14 | |
| 268. Missing Number (E) | 2021-07-15 | |
| 242. Valid Anagram (E) | 2021-07-15 | |
| 384. Shuffle an Array (M) | 2021-07-20 | ++ deep copy of list |
| 7. Reverse Integer (E) | 2021-07-21 | |
| 11. Container With Most Water (M) | 2021-07-25 | |
| 13. Roman to Integer (E) | 2021-07-27 | |
| 3. Longest Substring Without Repeating Characters (M) | 2021-07-28 | |
| 409. Longest Palindrome (E) | 2021-07-31 | |
| 383. Ransom Note (E) | 2021-08-02 | |
| 5. Longest Palindromic Substring (M) | 2021-08-05 | + |
| 169. Majority Element (E) | 2021-08-06 | + |
| 8. String to Integer (atoi) (M) | 2021-08-07 | + |
| 9. Palindrome Number | 2021-08-07 | |
| 12. Integer to Roman (M) | 2021-08-09 | |
| 14. Longest Common Prefix (E) | 2021-08-09 | |
| 26. Remove Duplicates from Sorted Array (E) | 2021-08-10 | |
| 16. 3Sum Closest(M) | 2021-08-11 | + |
| 35. Search Insert Position (E) | 2021-08-18 | |
| 48. Rotate Image (M) | 2021-08-18 | + |
| 43. Multiply Strings (M) | 2021-08-21 | |
| 49. Group Anagrams (M) | 2021-08-29 | |
| 36. Valid Sudoku (M) | 2021-08-30 | |
| 848. Shifting Letters (M) | 2021-09-08 | ord() and chr() |
| 56. Merge Intervals (M) | 2021-10-06 | |
| index | date | notes |
|---|---|---|
| 70. Climbing Stairs (E) | 2021-06-28 | |
| 121. Best Time to Buy and Sell Stock (E) | 2021-06-28 | + |
| 53. Maximum Subarray (E) | 2021-07-05 | - |
| 303. Range Sum Query - Immutable (E) | 2021-07-05 | ? |
| 46. Permutations (M) | 2021-07-06 | |
| 322. Coin Change (M) | 2021-07-08 | ++ |
| 338. Counting_Bits (E)) | 2021-07-08 | bin operation |
| 198. House Robber (M) | 2021-07-12 | + |
| 118. Pascal's Triangle (E) | 2021-07-28 | |
| 17. Letter Combinations of a Phone Number (M) | 2021-08-15 | Backtrack |
| 45. Jump Game II (M) | 2021-08-21 | |
| 55. Jump Game (M) | 2021-08-21 | |
| 198. House Robber (E) | 2021-09-11 | |
| 1911. Maximum Alternating Subsequence Sum (M) | 2021-09-12 | + |
| 300. Longest Increasing Subsequence (M) | 2021-09-12 | + |
| 416. Partition Equal Subset Sum (M) | 2021-09-12 | + |
| 213. House Robber II (M) | 2021-09-26 | |
| index | date | notes |
|---|---|---|
| 141. Linked List Cycle (E) | 2021-07-09 | |
| 876. Middle of the Linked List (E) | 2021-07-09 | |
| 206. Reverse Linked List (E) | 2021-07-10 | + |
| 19. Remove Nth Node From End of List (M) | 2021-07-11 | |
| 234. Palindrome Linked List (E) | 2021-07-12 | |
| 2. Add Two Numbers (M) | 2021-07-19 | |
| 82. Remove Duplicates from Sorted List II (M) | 2021-07-27 | + |
| 27. Remove Element (E) | 2021-08-01 | |
| 24. Swap Nodes in Pairs (M) | 2021-08-16 | ++ |
| index | date | notes |
|---|---|---|
| 20. Valid Parentheses (E) | 2021-07-16 | |
| 232. Implement Queue using Stacks (E) | 2021-07-18 | |
| 155. Min Stack (E) | 2021-07-27 | ^ |
| 641. Design Circular Deque (M) | 2021-08-01 | |
| 225. Implement Stack using Queues (E) | 2021-08-03 | |
| index | date | notes |
|---|---|---|
| 704. Binary Search (E) | 2021-07-23 | |
| 169. Majority Element (E) | 2021-07-29 | + |
| 15. 3Sum (M) | 2021-08-02 | + |
| 69. Sqrt(x) (E) | 2021-08-03 | + |
| 31. Next Permutation (M) | 2021-08-17 | ++ |
| 33. Search in Rotated Sorted Array (M) | 2021-08-26 | + |
| 34. Find First and Last Position of Element in Sorted Array (M) | 2021-08-26 | |
| index | date | notes |
|---|---|---|
| 98. Validate Binary Search Tree (M) | 2021-08-23 | + |
| 100. Same Tree (E) | 2021-08-23 | |
| 94. Binary Tree Inorder Traversal (E) | 2021-08-23 | |
| 96. Unique Binary Search Trees (M) | 2021-09-02 | |
| 95. Unique Binary Search Trees II (M) | 2021-09-07 | ++ |
| 987. Vertical Order Traversal of a Binary Tree (H) | 2021-10-08 | |