110. Balanced Binary Tree |
solution |
easy, bfs, trees |

102. Binary Tree Level Order Traversal |
solution |
Medium, bfs, trees |

107. Binary Tree Level Order Traversal II |
solution |
easy, bfs, trees |

101. Symmetric Tree |
solution |
easy, dfs, trees |

103. Binary Tree Zigzag Level Order Traversal |
solution |
Medium, bfs, trees |

199. Binary Tree Right Side View |
solution |
Medium, bfs, trees |

111. Minimum Depth of Binary Tree |
solution |
Easy, dfs, trees |

112. Path Sum |
solution |
Easy, bfs, trees |

113. Path Sum II |
solution |
Medium, bfs, backtrack, trees |

114. Flatten Binary Tree to Linked List |
solution |
Medium, bfs, trees |

100. Same Tree |
solution |
Easy, trees, bfs |

110. Balanced Binary Tree |
solution |
easy, tree, dfs |

1. Two Sum |
solution |
Easy, HashTable |

136. Single Number |
solution |
Easy, HashTable |

202. Happy Number |
solution |
Easy, Math, HashTable |

217. Contains Duplicate |
solution |
Easy, HashTable, Sets |

219. Contains Duplicate II |
solution |
Easy, HashTable |

1207. Unique Number of Occurrences |
solution |
Easy, HashTable |

13. Roman to Integer |
solution |
Easy, Strings |

151. Reverse Words in a String |
solution |
Medium, Strings |

14. Longest Common Prefix |
solution |
Easy, Strings |

67. Add Binary |
solution |
Easy, Strings |

22. Generate Parentheses |
solution |
Medium, Backtrack, Strings |

53. Maximum Subarray |
solution |
Easy, Dynamic Programming |

121. Best Time to Buy and Sell Stock |
solution |
Easy, Dynamic Programming |

122. Best Time to Buy and Sell Stock II |
solution |
Easy, Dynamic Programming |

62. Unique Paths |
solution |
Medium, Dynamic Programming |

120. Triangle |
solution |
Medium, Dynamic Programming |

49. Group Anagrams |
solution |
Medium, HashTable |

283. Move Zeroes |
solution |
Easy, Array |

844. Backspace String Compare |
solution |
Easy, String, Stack |

155. Min Stack |
solution |
Easy, Array, Stack |

543. Diameter of Binary Tree |
solution |
Easy, Trees, DFS |

5. Longest Palindromic Substring |
solution |
Medium, Strings |

144. Binary Tree Preorder Traversal |
solution |
Medium, dfs, trees |

94. Binary Tree Inorder Traversal |
solution |
Medium, dfs, trees |

739. Daily Temperatures |
solution |
Medium, Stack, Arrays |

3. Longest Substring Without Repeating Characters |
solution |
Medium, String, Arrays |

2. Add Two Numbers |
solution |
Medium, LinkedList |

300. Longest Increasing Subsequence |
solution |
Medium, Dynamic Programming |

46. Permutations |
solution |
Medium, Backtracking |

230. Kth Smallest Element in a BST |
solution |
Medium, Binary Search Tree, dfs |

56. Merge Intervals |
solution |
Medium, Arrays |

133. Clone Graph |
solution |
Medium, Graph |

841. Keys and Rooms |
solution |
Medium, Graph |