1. Two Sum [C, Swift]

7. Reverse Integer [C]

9. Palindrome Number [C]

13. Roman to Integer [C]

14. Longest Common Prefix [C]

20. Valid Parentheses [C]

21. Merge Two Sorted Lists [C]

26. Remove Duplicates from Sorted Array [C]

27. Remove Element [C]

28. Implement strStr() [C]

35. Search Insert Position [C]

38. Count and Say [C]

53. Maximum Subarray [Swift]

2. Add Two Numbers [C]

3. Longest Substring Without Repeating Characters [C]

5. Longest Palindromic Substring [C]

6. ZigZag Conversion [C]

8. String to Integer (atoi) [C]

11. Container With Most Water [C]

12. Integer to Roman [C]

15. 3Sum [C]

16. 3Sum Closest [C]

17. Letter Combinations of a Phone Number [C]

18. 4Sum [C]

19. Remove Nth Node From End of List [C]

22. Generate Parentheses [C]

24. Swap Nodes in Pairs [C]

29. Divide Two Integers [C]

31. Next Permutation [C]

33. Search in Rotated Sorted Array [C]

34. Search for a Range [C]

36. Valid Sudoku [C]

39. Combination Sum [C]

40. Combination Sum II [C]

43. Multiply Strings [C]

46. Permutations [C]

47. Permutations II [C]

48. Rotate Image [C]

49. Group Anagrams [C]

50. Pow(x, n) [C]

54. Spiral Matrix [Swift]

59. Spiral Matrix II [Swift]

4. Median of Two Sorted Arrays [C]

10. Regular Expression Matching [C]

23. Merge k Sorted Lists [C]

25. Reverse Nodes in k-Group [C]

30. Substring with Concatenation of All Words [C]

32. Longest Valid Parentheses [C]

37. Sudoku Solver [C]

41. First Missing Positive [C]

42. Trapping Rain Water [C]

44. Wildcard Matching [C]

45. Jump Game II [C]

51. N-Queens [Swift]

52. N-Queens II [Swift]