| 1 |
Two sum |
Solution |
Easy |
| 2 |
Add two numbers |
Solution |
Medium |
| 17 |
Letter combinations of a phone number |
Solution |
Medium |
| 20 |
Valid parentheses |
Solution |
Easy |
| 21 |
Merge two sorted lists |
Solution |
Easy |
| 22 |
Generate parentheses |
Solution |
Medium |
| 23 |
Merge K sorted lists |
Solution |
Hard |
| 35 |
Search insert position |
Solution |
Easy |
| 37 |
Sudoku solver |
Solution |
Hard |
| 39 |
Combination sum |
Solution |
Medium |
| 42 |
Trapping rain water |
Solution |
Hard |
| 46 |
Permutations |
Solution |
Medium |
| 53 |
Maximum subarray |
Solution |
Easy |
| 62 |
Unique paths |
Solution |
Medium |
| 63 |
Unique paths II |
Solution |
Medium |
| 64 |
Minimum path sum |
Solution |
Medium |
| 68 |
Text justification |
Solution |
Hard |
| 70 |
Climbing stairs |
Solution |
Easy |
| 79 |
Word search |
Solution |
Medium |
| 93 |
Restore IP addresses |
Solution |
Medium |
| 98 |
Validate binary search tree |
Solution |
Medium |
| 100 |
Same tree |
Solution |
Easy |
| 101 |
Symmetric tree |
Solution |
Easy |
| 102 |
Binary tree level order traversal |
Solution |
Medium |
| 103 |
Binary tree zigzag level order traversal |
Solution |
Medium |
| 104 |
Maximum depth of binary tree |
Solution |
Easy |
| 107 |
Binary tree level order traversal II |
Solution |
Easy |
| 110 |
Balanced binary tree |
Solution |
Easy |
| 111 |
Minimum depth of binary tree |
Solution |
Easy |
| 112 |
Path sum |
Solution |
Easy |
| 113 |
Path sum II |
Solution |
Medium |
| 118 |
Pascal's triangle |
Solution |
Easy |
| 127 |
Word ladder |
Solution |
Medium |
| 129 |
Sum root to leaf numbers |
Solution |
Medium |
| 144 |
Binary tree preorder traversal |
Solution |
Medium |
| 169 |
Majority element |
Solution |
Easy |
| 173 |
Binary search tree iterator |
Solution |
Medium |
| 199 |
Binary tree right side view |
Solution |
Medium |
| 200 |
Number of islands |
Solution |
Medium |
| 203 |
Remove linked list elements |
Solution |
Easy |
| 207 |
Course schedule |
Solution |
Medium |
| 208 |
Implement trie (prefix tree) |
Solution |
Medium |
| 217 |
Contains duplicate |
Solution |
Easy |
| 226 |
Invert binary tree |
Solution |
Easy |
| 230 |
Kth smallest element in a BST |
Solution |
Medium |
| 234 |
Palindrome linked list |
Solution |
Easy |
| 235 |
Lowest common ancestor of a binary search tree |
Solution |
Easy |
| 236 |
Lowest common ancestor of a binary tree |
Solution |
Medium |
| 242 |
Valid anagram |
Solution |
Easy |
| 263 |
Ugly number |
Solution |
Easy |
| 297 |
Serialize and deserialize binary tree |
Solution |
Hard |
| 383 |
Ransom note |
Solution |
Easy |
| 394 |
Decode string |
Solution |
Medium |
| 404 |
Sum of left leaves |
Solution |
Easy |
| 409 |
Longest palindrome |
Solution |
Easy |
| 419 |
Battleships in a board |
Solution |
Medium |
| 429 |
N-ary tree level order traversal |
Solution |
Easy |
| 443 |
Minimum genetic mutation |
Solution |
Medium |
| 451 |
Sort characters by frequency |
Solution |
Medium |
| 461 |
Hamming distance |
Solution |
Easy |
| 463 |
Island perimeter |
Solution |
Easy |
| 478 |
Generate random point in a circle |
Solution |
Medium |
| 508 |
Most frequent subtree sum |
Solution |
Medium |
| 509 |
Fibonacci number |
Solution |
Easy |
| 513 |
Find bottom left tree value |
Solution |
Medium |
| 538 |
Convert BST to greater tree |
Solution |
Easy |
| 547 |
Friend circles |
Solution |
Medium |
| 559 |
Maximum depth of n-ary tree |
Solution |
Easy |
| 567 |
Permutation in string |
Solution |
Medium |
| 590 |
N-ary tree postorder traversal |
Solution |
Easy |
| 617 |
Merge two binary trees |
Solution |
Easy |
| 623 |
Add one row to tree |
Solution |
Medium |
| 637 |
Average of levels in binary tree |
Solution |
Easy |
| 654 |
Maximum binary tree |
Solution |
Medium |
| 657 |
Robot return to origin |
Solution |
Easy |
| 684 |
Redundant connection |
Solution |
Medium |
| 695 |
Max area of island |
Solution |
Medium |
| 700 |
Search in a binary search tree |
Solution |
Easy |
| 704 |
Binary search |
Solution |
Easy |
| 729 |
My calendar I |
Solution |
Medium |
| 733 |
Flood fill |
Solution |
Easy |
| 735 |
Asteroid collision |
Solution |
Medium |
| 743 |
Network delay time |
Solution |
Medium |
| 746 |
Min cost climbing stairs |
Solution |
Easy |
| 771 |
Jewels and stones |
Solution |
Easy |
| 778 |
Swim in rising water |
Solution |
Hard |
| 784 |
Letter case permutation |
Solution |
Easy |
| 797 |
All paths from source to target |
Solution |
Medium |
| 802 |
Find eventual safe states |
Solution |
Medium |
| 814 |
Binary tree pruning |
Solution |
Medium |
| 844 |
Backspace string compare |
Solution |
Easy |
| 846 |
Hand of straights |
Solution |
Medium |
| 849 |
Maximize distance to closest person |
Solution |
Easy |
| 856 |
Score of parentheses |
Solution |
Medium |
| 863 |
All nodes distance K in binary tree |
Solution |
Medium |
| 872 |
Leaf-similar trees |
Solution |
Easy |
| 876 |
Middle of the linked list |
Solution |
Easy |
| 884 |
Uncommon words from two sentences |
Solution |
Easy |
| 917 |
Reverse only letters |
Solution |
Easy |
| 921 |
Minimum add to make parentheses valid |
Solution |
Medium |
| 931 |
Minimum falling path sum |
Solution |
Medium |
| 934 |
Shortest bridge |
Solution |
Medium |
| 935 |
Knight dialer |
Solution |
Medium |
| 938 |
Range sum of BST |
Solution |
Easy |
| 951 |
Flip equivalent binary trees |
Solution |
Medium |
| 958 |
Check completeness of a binary tree |
Solution |
Medium |
| 965 |
Univalued binary tree |
Solution |
Easy |
| 973 |
K closest points to origin |
Solution |
Medium |
| 980 |
Unique paths III |
Solution |
Hard |
| 988 |
Smallest string starting from leaf |
Solution |
Medium |
| 993 |
Cousins in binary tree |
Solution |
Easy |
| 994 |
Rotting oranges |
Solution |
Medium |
| 1020 |
Number of enclaves |
Solution |
Medium |
| 1021 |
Remove outermost parentheses |
Solution |
Easy |
| 1022 |
Sum of root to leaf binary numbers |
Solution |
Easy |
| 1038 |
Binary search tree to greater sum tree |
Solution |
Medium |
| 1046 |
Last stone weight |
Solution |
Easy |
| 1047 |
Remove all adjacent duplicates in string |
Solution |
Easy |
| 1110 |
Delete nodes and return forest |
Solution |
Medium |
| 1129 |
Shortest path with alternating colors |
Solution |
Medium |
| 1137 |
N-th Tribonacci number |
Solution |
Easy |
| 1161 |
Maximum level sum of a binary tree |
Solution |
Medium |
| 1184 |
Distance between bus stops |
Solution |
Easy |
| 1189 |
Maximum number of balloons |
Solution |
Easy |
| 1207 |
Unique number of occurrences |
Solution |
Easy |
| 1219 |
Path with maximum gold |
Solution |
Medium |
| 1220 |
Count vowels permutation |
Solution |
Hard |
| 1254 |
Number of closed islands |
Solution |
Medium |
| 1261 |
Find elements in a contaminated binary tree |
Solution |
Medium |
| 1290 |
Convert binary number in a linked list to integer |
Solution |
Easy |
| 1302 |
Deepest leaves sum |
Solution |
Medium |
| 1305 |
All elements in two binary search trees |
Solution |
Medium |
| 1306 |
Jump game III |
Solution |
Medium |
| 1313 |
Decompress run-length encoded list |
Solution |
Easy |
| 1315 |
Sum of nodes with even-valued grandparent |
Solution |
Medium |
| 1325 |
Delete leaves with a given value |
Solution |
Medium |
| 1342 |
Number of steps to reduce a number to zero |
Solution |
Easy |
| 1365 |
How many numbers are smaller than the current number |
Solution |
Easy |
| 1391 |
Check if there is a valid path in a grid |
Solution |
Medium |
| 1436 |
Destination city |
Solution |
Easy |
| 1417 |
Reformat the string |
Solution |
Easy |
| 1422 |
Maximum score after splitting a string |
Solution |
Easy |
| 1448 |
Count good nodes in binary tree |
Solution |
Medium |
| 1456 |
Maximum number of vowels in a substring... |
Solution |
Medium |
| 1470 |
Shuffle the array |
Solution |
Easy |
| 1480 |
Running sum of 1d array |
Solution |
Easy |
| 1496 |
Path crossing |
Solution |
Easy |
| 1518 |
Water bottles |
Solution |
Easy |
| 1528 |
Shuffle string |
Solution |
Easy |
| 1557 |
Minimum number of vertices to reach all nodes |
Solution |
Medium |
| 1559 |
Detect cycles in 2D grid |
Solution |
Hard |
| 1592 |
Rearrange spaces between words |
Solution |
Easy |
| 1598 |
Crawler log folder |
Solution |
Easy |
| 1609 |
Even odd tree |
Solution |
Medium |
| 1614 |
Maximum nesting depth of the parentheses |
Solution |
Easy |
| 1615 |
Maximal network rank |
Solution |
Medium |
| 1625 |
Lexicographically smallest string... |
Solution |
Medium |
| 1807 |
Evaluate the bracket pairs of a string |
Solution |
Medium |
| 1817 |
Finding the users active minutes |
Solution |
Medium |
| 1823 |
Find the winner of the circular game |
Solution |
Medium |
