1 | To lower case | Easy |

2 | Anagrams | Easy |

3 | Compare strings | Easy |

4 | Reverse string | Easy |

5 | Reverse words | Easy |

6 | Kth smallest node in a binary search tree | Medium |

7 | Reverse words 2 | Easy |

8 | Contains duplicate | Easy |

9 | Same tree | Easy |

10 | Reverse integer | Easy |

11 | Hamming weight | Easy |

12 | Missing number | Easy |

13 | Maximum subarray | Easy |

14 | Merge sorted lists | Hard |

15 | Unique number | Easy |

16 | First unique character | Easy |

17 | Longest common prefix | Easy |

18 | Valid palindrome | Easy |

19 | Valid parentheses | Easy |

20 | Majority item | Easy |

21 | Find difference | Easy |

22 | Detect capital | Easy |

23 | Excel sheet column number | Easy |

24 | Count bits | Medium |

25 | Reverse bits | Easy |

26 | Linked list cycle | Easy |

27 | Climb stairs | Easy |

28 | Arrays intersection | Easy |

29 | Largest Number | Medium |

30 | Subarrays of sum K | Medium |

31 | Find array duplicates | Medium |

32 | Arrays intersection 2 | Easy |

33 | Longest continuous increasing subsequence | Easy |

34 | Longest increasing subsequence | Medium |

35 | Maximum average subarray | Easy |

36 | Add one | Easy |

37 | Smallest subarray | Medium |

38 | Hamming distance | Easy |

39 | Jewels and stones | Easy |

40 | Longest substring without repeating | Medium |

41 | Sum of the left leaves | Easy |

42 | Symmetric tree | Easy |

43 | Invert binary tree | Easy |

44 | Maximum depth of a binary tree | Easy |

45 | Minimum depth of a binary tree | Easy |

46 | Averages of levels in a binary tree | Easy |

47 | Level order traversal of a binary tree | Easy |

48 | Balanced binary tree | Easy |

49 | Binary tree path sum | Easy |

50 | Binary tree sum numbers | Medium |