Leet code problems:
| No. | Problem | Difficulty | Topics |
|---|---|---|---|
| 1. | 1.Two Sum | Easy | |
| 2. | 9.Palindrome number | Easy | |
| 3. | 13.Roman to Integer | Easy | |
| 4. | 14.Longest Common Prefix | Easy | |
| 5. | 20.Valid Parentheses | Easy | string, stack |
| 6. | 21.Merge Two Sorted Lists | Easy | |
| 7. | 26.Remove Duplicates from Sorted | Easy | |
| 8. | 27.Remove Element | Easy | |
| 9. | 28.Find the Index of the First Occurrence in a String | Easy | |
| 10. | 35.Search Insert Position | Easy | |
| 11. | 58.Length of Last Word | Easy | |
| 12. | 771.Jewels and Stones | Easy | |
| 13. | 1365.How many numbers are smaller than the current number | Easy | |
| 14. | 763.Partition Labels | Medium | |
| 15. | 922.Sort Array By Parity II | Easy | Array, 2 pointers, Sorting |
| 16. | 125.Valid Palindrome | Easy | 2 pointers, String |
| 17. | 75.Sort Colors | Medium | 2 pointers, String, Array |
| 18. | 11.Container with most water | Medium | 2 pointers, greedy, array |
| 19. | 141.Linked List Cycle | Easy | 2 pointers, Linked List, HashMap |
| 20. | 237.Delete the node in a linked list | Medium | Linked List |
| 21. | 19. Remove Nth Node From End of List | Medium | Linked List, Two Pointers |
| 22. | 21. Merge Two Sorted Lists | Easy | Linked List, Two Pointers, Recursion |
| 23. | 234. Palindrome Linked Lists | Easy | Linked List, Two Pointers, Recursion, Stack |
| 24. | 203. Remove Linked List Elements | Easy | Linked List, Two Pointers, Recursion |
| 25. | 160. Intersection of 2 linked lists | Easy | Linked List, Two Pointers, Hash Table |
| 26. | 876. Middle of the linked list | Easy | Linked List, Two Pointers |
| 27. | 23. Merge K sorted lists | Hard | Linked List, Merge Sort |
| 28. | 643. Maximum Average Subarray 1 | Easy | Sliding window, array |
| 29. | 217. Contains duplicate I | Easy | array, hash table, sorting |
| 30. | 219. Contains duplicate II | Easy | Sliding window, array, hash table |
| 31. | 242. Valid Anagram | Easy | string, hash table, sorting |
| 32. | 49. Group Anagram | Medium | array, hash table, sort, string |
| 33. | 347. Top K Frequent Elements | Medium | array, hash table, divide and conquer, sort, heap, bucket sort, counting, quick select |
| 34. | 238. Product of array except itself | Medium | array, prefix sum |
| 35. | 36. Valid Sudoku | Medium | array, hash-table, matrix |
| 36. | 271. Encode and decode strings (+) | Medium | string |
| 37. | 128. Longest Consecutive Sequence | Medium | array, hash-table, union find |
| 38. | 167. Two Sums II (Sorted Input) | Medium | array, two pointers, binary search |
| 39. | 15. 3 Sum | Medium | array, two pointers, sorting |
| 40. | 42. Trapping Rain Water | Hard | array, two pointers, dynamic programming, stack/queue, monotonic stack |
| 41. | 155. Min Stack | Medium | stack, design |
| 42. | 150. Evaluate Reverse Polish Notation | Medium | stack, array, math |
| 43. | 22. Generate Parentheses | Medium | string, dynamic programming, backtracking |
| 44. | 739. Daily Temperatures | Medium | array, monotonic stack, stack |
| 45. | 84. Largest Rectangle in Histogram | Hard | array, monotonic stack, stack |
| 46. | 704. Binary Search | Easy | array, binary search |
| 47. | 278. First Bad Version | Easy | binary search, interactive |
| 48. | 69. Sqrt(x) | Easy | binary search, math |