| E |
1. Two Sum |
| M |
2. Add Two Numbers |
| M |
3. Longest Substring Without Repeating Characters |
| M |
5. Longest Palindromic Substring |
| M |
6. ZigZag Conversion |
| E |
7. Reverse Integer |
| E |
9. Palindrome Number |
| M |
11. Container With Most Water |
| M |
12. Integer to Roman |
| E |
13. Roman to Integer |
| E |
14. Longest Common Prefix |
| M |
15. 3Sum |
| M |
16. 3Sum Closest |
| M |
17. Letter Combinations of a Phone Number |
| E |
20. Valid Parentheses |
| E |
21. Merge Two Sorted Lists |
| M |
22. Generate Parentheses |
| E |
26. Remove Duplicates from Sorted Array |
| E |
27. Remove Element |
| E |
28. Implement strStr() |
| M |
31. Next Permutation |
| M |
33. Search in Rotated Sorted Array |
| M |
34. Find First and Last Position of Element in Sorted Array |
| E |
35. Search Insert Position |
| M |
36. Valid Sudoku |
| M |
38. Count and Say |
| M |
39. Combination Sum |
| M |
40. Combination Sum II |
| H |
42. Trapping Rain Water |
| M |
43. Multiply Strings |
| M |
45. Jump Game II |
| M |
46. Permutations |
| M |
47. Permutations II |
| M |
48. Rotate Image |
| M |
49. Group Anagrams |
| M |
50. Pow(x, n) |
| H |
51. N-Queens |
| H |
52. N-Queens II |
| M |
53. Maximum Subarray |
| M |
54. Spiral Matrix |
| M |
55. Jump Game |
| M |
56. Merge Intervals |
| M |
57. Insert Interval |
| E |
58. Length of Last Word |
| M |
59. Spiral Matrix II |