| Crack The Coding Interview |
|
|
| # |
Topic |
Question |
Difficulty |
|
|
|
|
| 1 |
Array, Hash Table |
https://leetcode.com/problems/two-sum |
Easy |
| 2 |
Hash Table, String, Sliding Window |
https://leetcode.com/problems/longest-substring-without-repeating-characters |
Medium |
| 3 |
Array, Divide and Conquer, Dynamic Programming |
https://leetcode.com/problems/maximum-subarray |
Easy |
| 4 |
Array, Two Pointers, Dynamic Programming, Stack, Monotonic Stack |
https://leetcode.com/problems/trapping-rain-water |
Hard |
| 5 |
Linked List, Math, Recursion |
https://leetcode.com/problems/add-two-numbers |
Medium |
| 6 |
Array, Two Pointers, Sorting |
https://leetcode.com/problems/3sum |
Medium |
| 7 |
String, Dynamic Programming |
https://leetcode.com/problems/longest-palindromic-substring |
Medium |
| 8 |
Array, Binary Search, Divide and Conquer |
https://leetcode.com/problems/median-of-two-sorted-arrays |
Hard |
| 9 |
Array, Two Pointers, Greedy |
https://leetcode.com/problems/container-with-most-water |
Medium |
| 10 |
Array, Dynamic Programming |
https://leetcode.com/problems/best-time-to-buy-and-sell-stock |
Easy |
| 11 |
Array, Binary Search |
https://leetcode.com/problems/search-in-rotated-sorted-array |
Medium |
| 12 |
Array, Depth-First Search, Breadth-First Search, Union Find, Matrix |
https://leetcode.com/problems/number-of-islands |
Medium |
| 13 |
Hash Table, Linked List, Design, Doubly-Linked List |
https://leetcode.com/problems/lru-cache |
Medium |
| 14 |
Array, Sorting |
https://leetcode.com/problems/merge-intervals |
Medium |
| 15 |
String, Dynamic Programming, Backtracking |
https://leetcode.com/problems/generate-parentheses |
Medium |
| 16 |
Array, Two Pointers, Binary Search, Bit Manipulation |
https://leetcode.com/problems/find-the-duplicate-number |
Medium |
| 17 |
Array, Prefix Sum |
https://leetcode.com/problems/product-of-array-except-self |
Medium |
| 18 |
String, Stack |
https://leetcode.com/problems/valid-parentheses |
Easy |
| 19 |
Array, Hash Table, Prefix Sum |
https://leetcode.com/problems/subarray-sum-equals-k |
Medium |
| 20 |
Array, Dynamic Programming |
https://leetcode.com/problems/house-robber |
Medium |
| 21 |
Array, Binary Search, Dynamic Programming |
https://leetcode.com/problems/longest-increasing-subsequence |
Medium |
| 22 |
Linked List, Recursion |
https://leetcode.com/problems/reverse-linked-list |
Easy |
| 23 |
Array, Dynamic Programming |
https://leetcode.com/problems/maximum-product-subarray |
Medium |
| 24 |
Linked List, Divide and Conquer, Heap (Priority Queue), Merge Sort |
https://leetcode.com/problems/merge-k-sorted-lists |
Hard |
| 25 |
Linked List, Recursion |
https://leetcode.com/problems/merge-two-sorted-lists |
Easy |
| 26 |
Math, Dynamic Programming, Memoization |
https://leetcode.com/problems/climbing-stairs |
Easy |
| 27 |
Array, Dynamic Programming, Breadth-First Search |
https://leetcode.com/problems/coin-change |
Medium |
| 28 |
Array, Dynamic Programming, Greedy |
https://leetcode.com/problems/jump-game |
Medium |
| 29 |
Hash Table, String, Dynamic Programming, Trie, Memoization |
https://leetcode.com/problems/word-break |
Medium |
| 30 |
Hash Table, String, Sliding Window |
https://leetcode.com/problems/minimum-window-substring |
Hard |
| 31 |
Array, Binary Search |
https://leetcode.com/problems/find-first-and-last-position-of-element-in-sorted-array |
Medium |
| 32 |
Array, Backtracking |
https://leetcode.com/problems/permutations |
Medium |
| 33 |
Array, Backtracking |
https://leetcode.com/problems/combination-sum |
Medium |
| 34 |
Hash Table, String, Backtracking |
https://leetcode.com/problems/letter-combinations-of-a-phone-number |
Medium |
| 35 |
Tree, Depth-First Search, Binary Search Tree, Binary Tree |
https://leetcode.com/problems/validate-binary-search-tree |
Medium |
| 36 |
Array, Queue, Sliding Window, Heap (Priority Queue), Monotonic Queue |
https://leetcode.com/problems/sliding-window-maximum |
Hard |
| 37 |
Tree, Depth-First Search, Binary Tree |
https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-tree |
Medium |
| 38 |
Tree, Depth-First Search, Breadth-First Search, Binary Tree |
https://leetcode.com/problems/symmetric-tree |
Easy |
| 39 |
Array, Two Pointers |
https://leetcode.com/problems/next-permutation |
Medium |
| 40 |
Array, Two Pointers, Sorting |
https://leetcode.com/problems/sort-colors |
Medium |
| 41 |
Linked List, Two Pointers |
https://leetcode.com/problems/remove-nth-node-from-end-of-list |
Medium |
| 42 |
Array, Bit Manipulation |
https://leetcode.com/problems/single-number |
Easy |
| 43 |
Array, Stack, Monotonic Stack |
https://leetcode.com/problems/largest-rectangle-in-histogram |
Hard |
| 44 |
Array, Hash Table |
https://leetcode.com/problems/first-missing-positive |
Hard |
| 45 |
Depth-First Search, Breadth-First Search, Graph, Topological Sort |
https://leetcode.com/problems/course-schedule |
Medium |
| 46 |
Dynamic Programming, Tree, Depth-First Search, Binary Tree |
https://leetcode.com/problems/binary-tree-maximum-path-sum |
Hard |
| 47 |
Array, Backtracking, Matrix |
https://leetcode.com/problems/word-search |
Medium |
| 48 |
Array, Backtracking, Bit Manipulation |
https://leetcode.com/problems/subsets |
Medium |
| 49 |
Array, Hash Table, Union Find |
https://leetcode.com/problems/longest-consecutive-sequence |
Medium |
| 50 |
Array, Divide and Conquer, Sorting, Heap (Priority Queue), Quickselect |
https://leetcode.com/problems/kth-largest-element-in-an-array |
Medium |
| 51 |
Hash Table, String, Sorting |
https://leetcode.com/problems/group-anagrams |
Medium |
| 52 |
Array, Two Pointers |
https://leetcode.com/problems/move-zeroes |
Easy |
| 53 |
Hash Table, Linked List, Two Pointers |
https://leetcode.com/problems/intersection-of-two-linked-lists |
Easy |
| 54 |
Array, Hash Table, Divide and Conquer, Sorting, Counting |
https://leetcode.com/problems/majority-element |
Easy |
| 55 |
Math, Dynamic Programming, Combinatorics |
https://leetcode.com/problems/unique-paths |
Medium |
| 56 |
Array, Math, Matrix |
https://leetcode.com/problems/rotate-image |
Medium |
| 57 |
Linked List, Two Pointers, Stack, Recursion |
https://leetcode.com/problems/palindrome-linked-list |
Easy |
| 58 |
String, Dynamic Programming |
https://leetcode.com/problems/edit-distance |
Hard |
| 59 |
String, Dynamic Programming, Recursion |
https://leetcode.com/problems/regular-expression-matching |
Hard |
| 60 |
Array, Hash Table, Divide and Conquer, Tree, Binary Tree |
https://leetcode.com/problems/construct-binary-tree-from-preorder-and-inorder-traversal |
Medium |
| 61 |
Tree, Depth-First Search, Breadth-First Search, Binary Tree |
https://leetcode.com/problems/invert-binary-tree |
Easy |
| 62 |
Array, Math, Two Pointers |
https://leetcode.com/problems/rotate-array |
Medium |
| 63 |
String, Stack, Recursion |
https://leetcode.com/problems/decode-string |
Medium |
| 64 |
Stack, Design |
https://leetcode.com/problems/min-stack |
Easy |
| 65 |
Array, Hash Table, Divide and Conquer, Sorting, Heap (Priority Queue), Bucket Sort, Counting, Quickselect |
https://leetcode.com/problems/top-k-frequent-elements |
Medium |
| 66 |
Hash Table, Linked List |
https://leetcode.com/problems/copy-list-with-random-pointer |
Medium |
| 67 |
String, Dynamic Programming, Stack |
https://leetcode.com/problems/longest-valid-parentheses |
Hard |
| 68 |
Tree, Depth-First Search, Binary Tree |
https://leetcode.com/problems/path-sum-iii |
Medium |
| 69 |
Tree, Breadth-First Search, Binary Tree |
https://leetcode.com/problems/binary-tree-level-order-traversal |
Medium |
| 70 |
Tree, Depth-First Search, Binary Tree |
https://leetcode.com/problems/diameter-of-binary-tree |
Easy |
| 71 |
Array, Dynamic Programming, Greedy |
https://leetcode.com/problems/jump-game-ii |
Medium |
| 72 |
Array, Dynamic Programming |
https://leetcode.com/problems/partition-equal-subset-sum |
Medium |
| 73 |
Stack, Tree, Depth-First Search, Binary Tree |
https://leetcode.com/problems/binary-tree-inorder-traversal |
Easy |
| 74 |
Hash Table, String, Breadth-First Search |
https://leetcode.com/problems/word-ladder |
Hard |
| 75 |
Math, Dynamic Programming, Tree, Binary Search Tree, Binary Tree |
https://leetcode.com/problems/unique-binary-search-trees |
Medium |
| 76 |
Hash Table, Linked List, Two Pointers |
https://leetcode.com/problems/linked-list-cycle |
Easy |
| 77 |
Array, Dynamic Programming, Matrix |
https://leetcode.com/problems/maximal-square |
Medium |
| 78 |
String |
https://leetcode.com/problems/longest-common-prefix |
Easy |
| 79 |
Array, Dynamic Programming, Greedy |
https://leetcode.com/problems/best-time-to-buy-and-sell-stock-ii |
Medium |
| 80 |
Array, Dynamic Programming, Matrix |
https://leetcode.com/problems/minimum-path-sum |
Medium |
| 81 |
Array, Binary Search, Divide and Conquer, Matrix |
https://leetcode.com/problems/search-a-2d-matrix-ii |
Medium |
| 82 |
Math |
https://leetcode.com/problems/reverse-integer |
Medium |
| 83 |
Array, Binary Search |
https://leetcode.com/problems/search-insert-position |
Easy |
| 84 |
Linked List, Stack, Tree, Depth-First Search, Binary Tree |
https://leetcode.com/problems/flatten-binary-tree-to-linked-list |
Medium |
| 85 |
Hash Table, String, Design, Trie |
https://leetcode.com/problems/implement-trie-prefix-tree |
Medium |
| 86 |
Array, Stack, Monotonic Stack |
https://leetcode.com/problems/daily-temperatures |
Medium |
| 87 |
Hash Table, Two Pointers, String, Greedy |
https://leetcode.com/problems/partition-labels |
Medium |
| 88 |
Math, Dynamic Programming, Breadth-First Search |
https://leetcode.com/problems/perfect-squares |
Medium |
| 89 |
String, Dynamic Programming |
https://leetcode.com/problems/decode-ways |
Medium |
| 90 |
Two Pointers, Design, Sorting, Heap (Priority Queue), Data Stream |
https://leetcode.com/problems/find-median-from-data-stream |
Hard |
| 91 |
Array, Dynamic Programming, Stack, Matrix, Monotonic Stack |
https://leetcode.com/problems/maximal-rectangle |
Hard |
| 92 |
Array, Hash Table, Greedy, Sorting, Heap (Priority Queue), Counting |
https://leetcode.com/problems/task-scheduler |
Medium |
| 93 |
Linked List, Recursion |
https://leetcode.com/problems/reverse-nodes-in-k-group |
Hard |
| 94 |
Array, Matrix, Simulation |
https://leetcode.com/problems/spiral-matrix |
Medium |
| 95 |
Array, Dynamic Programming, Backtracking |
https://leetcode.com/problems/target-sum |
Medium |
| 96 |
Array, Hash Table |
https://leetcode.com/problems/find-all-numbers-disappeared-in-an-array |
Easy |
| 97 |
Depth-First Search, Breadth-First Search, Graph, Topological Sort |
https://leetcode.com/problems/course-schedule-ii |
Medium |
| 98 |
Tree, Depth-First Search, Breadth-First Search, Binary Tree |
https://leetcode.com/problems/merge-two-binary-trees |
Easy |
| 99 |
String, Tree, Depth-First Search, Breadth-First Search, Design, Binary Tree |
https://leetcode.com/problems/serialize-and-deserialize-binary-tree |
Hard |
| 100 |
Hash Table, Linked List, Two Pointers |
https://leetcode.com/problems/linked-list-cycle-ii |
Medium |
| 101 |
Dynamic Programming, Tree, Depth-First Search, Binary Tree |
https://leetcode.com/problems/house-robber-iii |
Medium |
| 102 |
Linked List, Two Pointers, Divide and Conquer, Sorting, Merge Sort |
https://leetcode.com/problems/sort-list |
Medium |
| 103 |
Hash Table, String, Sliding Window |
https://leetcode.com/problems/find-all-anagrams-in-a-string |
Medium |
| 104 |
Tree, Depth-First Search, Breadth-First Search, Binary Tree |
https://leetcode.com/problems/binary-tree-right-side-view |
Medium |
| 105 |
String, Dynamic Programming |
https://leetcode.com/problems/palindromic-substrings |
Medium |
| 106 |
Tree, Depth-First Search, Breadth-First Search, Binary Tree |
https://leetcode.com/problems/maximum-depth-of-binary-tree |
Easy |
| 107 |
Array, Breadth-First Search, Matrix |
https://leetcode.com/problems/rotting-oranges |
Medium |
| 108 |
Array, Hash Table, Matrix |
https://leetcode.com/problems/set-matrix-zeroes |
Medium |
| 109 |
Array, Divide and Conquer, Tree, Binary Search Tree, Binary Tree |
https://leetcode.com/problems/convert-sorted-array-to-binary-search-tree |
Easy |
| 110 |
Array, Binary Search, Matrix |
https://leetcode.com/problems/search-a-2d-matrix |
Medium |
| 111 |
Array, Binary Search |
https://leetcode.com/problems/find-minimum-in-rotated-sorted-array |
Medium |
| 112 |
Tree, Depth-First Search, Breadth-First Search, Binary Tree |
https://leetcode.com/problems/populating-next-right-pointers-in-each-node |
Medium |
| 113 |
Array, Two Pointers |
https://leetcode.com/problems/remove-duplicates-from-sorted-array |
Easy |
| 114 |
Tree, Depth-First Search, Binary Search Tree, Binary Tree |
https://leetcode.com/problems/kth-smallest-element-in-a-bst |
Medium |
| 115 |
Array, Binary Search, Sliding Window, Prefix Sum |
https://leetcode.com/problems/minimum-size-subarray-sum |
Medium |
| 116 |
Array, Hash Table |
https://leetcode.com/problems/find-all-duplicates-in-an-array |
Medium |
| 117 |
Array, Dynamic Programming |
https://leetcode.com/problems/burst-balloons |
Hard |
| 118 |
Dynamic Programming, Bit Manipulation |
https://leetcode.com/problems/counting-bits |
Easy |
| 119 |
Tree, Depth-First Search, Breadth-First Search, Binary Tree |
https://leetcode.com/problems/all-nodes-distance-k-in-binary-tree |
Medium |
| 120 |
Linked List, Recursion |
https://leetcode.com/problems/swap-nodes-in-pairs |
Medium |
| 121 |
Linked List |
https://leetcode.com/problems/reverse-linked-list-ii |
Medium |
| 122 |
Array, String, Backtracking, Trie, Matrix |
https://leetcode.com/problems/word-search-ii |
Hard |
| 123 |
String, Dynamic Programming |
https://leetcode.com/problems/longest-common-subsequence |
Medium |
| 124 |
Array, Binary Search, Sorting, Heap (Priority Queue), Matrix |
https://leetcode.com/problems/kth-smallest-element-in-a-sorted-matrix |
Medium |
| 125 |
Array, Two Pointers, Sorting |
https://leetcode.com/problems/4sum |
Medium |
| 126 |
Array, Dynamic Programming |
https://leetcode.com/problems/best-time-to-buy-and-sell-stock-iii |
Hard |
| 127 |
Array, Dynamic Programming |
https://leetcode.com/problems/best-time-to-buy-and-sell-stock-with-cooldown |
Medium |
| 128 |
String, Dynamic Programming, Backtracking |
https://leetcode.com/problems/palindrome-partitioning |
Medium |
| 129 |
Linked List, Two Pointers, Stack, Recursion |
https://leetcode.com/problems/reorder-list |
Medium |
| 130 |
Array, Dynamic Programming |
https://leetcode.com/problems/min-cost-climbing-stairs |
Easy |
| 131 |
Array, Depth-First Search, Breadth-First Search, Union Find, Matrix |
https://leetcode.com/problems/max-area-of-island |
Medium |
| 132 |
Array, Binary Search, Divide and Conquer, Binary Indexed Tree, Segment Tree, Merge Sort, Ordered Set |
https://leetcode.com/problems/count-of-smaller-numbers-after-self |
Hard |
| 133 |
Array, Two Pointers, Sorting |
https://leetcode.com/problems/3sum-closest |
Medium |
| 134 |
Tree, Breadth-First Search, Binary Tree |
https://leetcode.com/problems/binary-tree-zigzag-level-order-traversal |
Medium |
| 135 |
Array, Binary Search |
https://leetcode.com/problems/find-peak-element |
Medium |
| 136 |
Array, Hash Table, Math, Design, Randomized |
https://leetcode.com/problems/insert-delete-getrandom-o1 |
Medium |
| 137 |
Tree, Depth-First Search, Binary Tree |
https://leetcode.com/problems/balanced-binary-tree |
Easy |
| 138 |
Math |
https://leetcode.com/problems/palindrome-number |
Easy |
| 139 |
Array, Backtracking |
https://leetcode.com/problems/n-queens |
Hard |
| 140 |
Array, Math, Divide and Conquer, Geometry, Sorting, Heap (Priority Queue), Quickselect |
https://leetcode.com/problems/k-closest-points-to-origin |
Medium |
| 141 |
Linked List |
https://leetcode.com/problems/odd-even-linked-list |
Medium |
| 142 |
Depth-First Search, Breadth-First Search, Graph, Topological Sort |
https://leetcode.com/problems/minimum-height-trees |
Medium |
| 143 |
Tree, Depth-First Search, Breadth-First Search, Binary Tree |
https://leetcode.com/problems/same-tree |
Easy |
| 144 |
Tree, Depth-First Search, Binary Search Tree, Binary Tree |
https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-search-tree |
Easy |
| 145 |
Array, Two Pointers, Stack, Greedy, Sorting, Monotonic Stack |
https://leetcode.com/problems/shortest-unsorted-continuous-subarray |
Medium |
| 146 |
Stack, Tree, Design, Binary Search Tree, Binary Tree, Iterator |
https://leetcode.com/problems/binary-search-tree-iterator |
Medium |
| 147 |
Dynamic Programming, Depth-First Search, Breadth-First Search, Graph, Topological Sort, Memoization |
https://leetcode.com/problems/longest-increasing-path-in-a-matrix |
Hard |
| 148 |
Array, Greedy, Sorting |
https://leetcode.com/problems/queue-reconstruction-by-height |
Medium |
| 149 |
Tree, Depth-First Search, Binary Tree |
https://leetcode.com/problems/path-sum |
Easy |
| 150 |
Tree, Binary Search Tree, Binary Tree |
https://leetcode.com/problems/delete-node-in-a-bst |
Medium |
| 151 |
Tree, Depth-First Search, String Matching, Binary Tree, Hash Function |
https://leetcode.com/problems/subtree-of-another-tree |
Easy |
| 152 |
Array, Hash Table, Math, Bit Manipulation, Sorting |
https://leetcode.com/problems/missing-number |
Easy |
| 153 |
String, Dynamic Programming |
https://leetcode.com/problems/longest-palindromic-subsequence |
Medium |
| 154 |
Array, Depth-First Search, Breadth-First Search, Union Find, Graph, Shortest Path |
https://leetcode.com/problems/evaluate-division |
Medium |
| 155 |
Array, Dynamic Programming |
https://leetcode.com/problems/house-robber-ii |
Medium |
| 156 |
Array, Dynamic Programming |
https://leetcode.com/problems/pascals-triangle |
Easy |
| 157 |
Hash Table, Depth-First Search, Breadth-First Search, Graph |
https://leetcode.com/problems/clone-graph |
Medium |
| 158 |
Array, Dynamic Programming |
https://leetcode.com/problems/coin-change-2 |
Medium |
| 159 |
Hash Table, Math, Two Pointers |
https://leetcode.com/problems/happy-number |
Easy |
| 160 |
Depth-First Search, Breadth-First Search, Union Find, Graph |
https://leetcode.com/problems/number-of-provinces |
Medium |
| 161 |
Array, Binary Search |
https://leetcode.com/problems/single-element-in-a-sorted-array |
Medium |
| 162 |
Array, Greedy |
https://leetcode.com/problems/gas-station |
Medium |
| 163 |
Dynamic Programming, Backtracking, Tree, Binary Search Tree, Binary Tree |
https://leetcode.com/problems/unique-binary-search-trees-ii |
Medium |
| 164 |
Dynamic Programming, Depth-First Search, Breadth-First Search, Graph, Heap (Priority Queue), Shortest Path |
https://leetcode.com/problems/cheapest-flights-within-k-stops |
Medium |
| 165 |
Linked List, Two Pointers |
https://leetcode.com/problems/middle-of-the-linked-list |
Easy |
| 166 |
String, Stack, Greedy, Monotonic Stack |
https://leetcode.com/problems/remove-k-digits |
Medium |
| 167 |
Array, Backtracking, Matrix |
https://leetcode.com/problems/sudoku-solver |
Hard |
| 168 |
Array, Depth-First Search, Breadth-First Search, Union Find, Matrix |
https://leetcode.com/problems/surrounded-regions |
Medium |
| 169 |
Binary Search, Tree, Depth-First Search, Binary Tree |
https://leetcode.com/problems/count-complete-tree-nodes |
Medium |
| 170 |
String, Backtracking, Breadth-First Search |
https://leetcode.com/problems/remove-invalid-parentheses |
Hard |
| 171 |
Array, Dynamic Programming, Backtracking, Bit Manipulation, Memoization, Bitmask |
https://leetcode.com/problems/partition-to-k-equal-sum-subsets |
Medium |
| 172 |
Array, Two Pointers, Binary Search |
https://leetcode.com/problems/two-sum-ii-input-array-is-sorted |
Easy |
| 173 |
Hash Table, String, Queue, Counting |
https://leetcode.com/problems/first-unique-character-in-a-string |
Easy |
| 174 |
String, Greedy, Sorting |
https://leetcode.com/problems/largest-number |
Medium |
| 175 |
Array, Math, Enumeration, Number Theory |
https://leetcode.com/problems/count-primes |
Medium |
| 176 |
Array, Two Pointers, Sorting |
https://leetcode.com/problems/squares-of-a-sorted-array |
Easy |
| 177 |
Array, Backtracking |
https://leetcode.com/problems/permutations-ii |
Medium |
| 178 |
Hash Table, String, Dynamic Programming, Backtracking, Trie, Memoization |
https://leetcode.com/problems/word-break-ii |
Hard |
| 179 |
Array, Backtracking |
https://leetcode.com/problems/combination-sum-ii |
Medium |
| 180 |
Array, Dynamic Programming |
https://leetcode.com/problems/triangle |
Medium |
| 181 |
Linked List, Recursion |
https://leetcode.com/problems/remove-linked-list-elements |
Easy |
| 182 |
Linked List, Two Pointers |
https://leetcode.com/problems/remove-duplicates-from-sorted-list-ii |
Medium |
| 183 |
Array, Hash Table, Matrix |
https://leetcode.com/problems/valid-sudoku |
Medium |
| 184 |
Backtracking, Tree, Depth-First Search, Binary Tree |
https://leetcode.com/problems/path-sum-ii |
Medium |
| 185 |
Linked List, Divide and Conquer, Tree, Binary Search Tree, Binary Tree |
https://leetcode.com/problems/convert-sorted-list-to-binary-search-tree |
Medium |
| 186 |
Array |
https://leetcode.com/problems/insert-interval |
Medium |
| 187 |
String, Dynamic Programming, Greedy, Recursion |
https://leetcode.com/problems/wildcard-matching |
Hard |
| 188 |
Array, Backtracking, Bit Manipulation |
https://leetcode.com/problems/subsets-ii |
Medium |
| 189 |
Array, Dynamic Programming, Matrix |
https://leetcode.com/problems/unique-paths-ii |
Medium |
| 190 |
Array, Binary Search, Dynamic Programming, Greedy |
https://leetcode.com/problems/split-array-largest-sum |
Hard |
| 191 |
Hash Table, String, Greedy, Sorting, Heap (Priority Queue), Counting |
https://leetcode.com/problems/reorganize-string |
Medium |
| 192 |
Hash Table, Two Pointers, String, Sliding Window |
https://leetcode.com/problems/permutation-in-string |
Medium |
| 193 |
Array, Hash Table, Sorting, Counting |
https://leetcode.com/problems/majority-element-ii |
Medium |
| 194 |
Array, Hash Table, Divide and Conquer, Tree, Binary Tree |
https://leetcode.com/problems/construct-binary-tree-from-inorder-and-postorder-traversal |
Medium |
| 195 |
Array, Dynamic Programming |
https://leetcode.com/problems/minimum-cost-for-tickets |
Medium |
| 196 |
Hash Table, String, Trie, Sorting, Heap (Priority Queue), Bucket Sort, Counting |
https://leetcode.com/problems/top-k-frequent-words |
Medium |
| 197 |
Array, Depth-First Search, Breadth-First Search, Matrix |
https://leetcode.com/problems/island-perimeter |
Easy |
| 198 |
Linked List |
https://leetcode.com/problems/remove-duplicates-from-sorted-list |
Easy |
| 199 |
Math, String, Bit Manipulation, Simulation |
https://leetcode.com/problems/add-binary |
Easy |
| 200 |
Array, Dynamic Programming, Breadth-First Search, Matrix |
https://leetcode.com/problems/01-matrix |
Medium |
| 201 |
Hash Table, String, Sorting |
https://leetcode.com/problems/valid-anagram |
Easy |
| 202 |
Math, String, Simulation |
https://leetcode.com/problems/multiply-strings |
Medium |
| 203 |
Binary Search, Interactive |
https://leetcode.com/problems/first-bad-version |
Easy |
| 204 |
String, Depth-First Search, Design, Trie |
https://leetcode.com/problems/design-add-and-search-words-data-structure |
Medium |
| 205 |
Array, Stack, Monotonic Stack |
https://leetcode.com/problems/next-greater-element-ii |
Medium |
| 206 |
Math, String, Stack |
https://leetcode.com/problems/basic-calculator-ii |
Medium |
| 207 |
Array, String, Depth-First Search, Breadth-First Search, Union Find |
https://leetcode.com/problems/accounts-merge |
Medium |
| 208 |
Two Pointers, String, Greedy |
https://leetcode.com/problems/valid-palindrome-ii |
Easy |
| 209 |
Linked List |
https://leetcode.com/problems/delete-node-in-a-linked-list |
Easy |
| 210 |
Array, Two Pointers |
https://leetcode.com/problems/interval-list-intersections |
Medium |
| 211 |
Linked List, Two Pointers |
https://leetcode.com/problems/rotate-list |
Medium |
| 212 |
Tree, Depth-First Search, Binary Tree |
https://leetcode.com/problems/sum-root-to-leaf-numbers |
Medium |
| 213 |
Array, Dynamic Programming, Matrix |
https://leetcode.com/problems/dungeon-game |
Hard |
| 214 |
Math, Recursion |
https://leetcode.com/problems/powx-n |
Medium |
| 215 |
Array, Binary Search, Sliding Window, Prefix Sum |
https://leetcode.com/problems/max-consecutive-ones-iii |
Medium |
| 216 |
Array, Hash Table, Two Pointers, Binary Search, Sorting |
https://leetcode.com/problems/intersection-of-two-arrays-ii |
Easy |
| 217 |
String, Stack, Greedy, Monotonic Stack |
https://leetcode.com/problems/remove-duplicate-letters |
Medium |
| 218 |
Tree, Depth-First Search, Binary Search Tree, Binary Tree |
https://leetcode.com/problems/recover-binary-search-tree |
Medium |
| 219 |
Depth-First Search, Breadth-First Search, Union Find, Graph |
https://leetcode.com/problems/is-graph-bipartite |
Medium |
| 220 |
Array, Hash Table, Prefix Sum |
https://leetcode.com/problems/contiguous-array |
Medium |
| 221 |
Array, Two Pointers, Binary Search, Sorting, Heap (Priority Queue) |
https://leetcode.com/problems/find-k-closest-elements |
Medium |
| 222 |
Two Pointers, String, Recursion |
https://leetcode.com/problems/reverse-string |
Easy |
| 223 |
Tree, Depth-First Search, Binary Search Tree, Binary Tree |
https://leetcode.com/problems/range-sum-of-bst |
Easy |
| 224 |
Hash Table, String, Sorting, Heap (Priority Queue), Bucket Sort, Counting |
https://leetcode.com/problems/sort-characters-by-frequency |
Medium |
| 225 |
Hash Table, String, Sliding Window |
https://leetcode.com/problems/longest-repeating-character-replacement |
Medium |
| 226 |
Stack, Tree, Depth-First Search, Binary Tree |
https://leetcode.com/problems/binary-tree-postorder-traversal |
Easy |
| 227 |
Array, Bit Manipulation |
https://leetcode.com/problems/single-number-ii |
Medium |
| 228 |
Hash Table, Math, Dynamic Programming, Heap (Priority Queue) |
https://leetcode.com/problems/ugly-number-ii |
Medium |
| 229 |
Depth-First Search, Graph, Eulerian Circuit |
https://leetcode.com/problems/reconstruct-itinerary |
Hard |
| 230 |
Array, Divide and Conquer, Binary Indexed Tree, Segment Tree, Line Sweep, Heap (Priority Queue), Ordered Set |
https://leetcode.com/problems/the-skyline-problem |
Hard |
| 231 |
Array, Bit Manipulation |
https://leetcode.com/problems/single-number-iii |
Medium |
| 232 |
Two Pointers, String, Dynamic Programming |
https://leetcode.com/problems/is-subsequence |
Easy |
| 233 |
Depth-First Search, Breadth-First Search, Graph, Heap (Priority Queue), Shortest Path |
https://leetcode.com/problems/network-delay-time |
Medium |
| 234 |
String, Tree, Depth-First Search, Binary Tree |
https://leetcode.com/problems/binary-tree-paths |
Easy |
| 235 |
Hash Table, String, Divide and Conquer, Sliding Window |
https://leetcode.com/problems/longest-substring-with-at-least-k-repeating-characters |
Medium |
| 236 |
Tree, Depth-First Search, Breadth-First Search, Binary Tree |
https://leetcode.com/problems/minimum-depth-of-binary-tree |
Easy |
| 237 |
Array, Dynamic Programming, Greedy |
https://leetcode.com/problems/best-time-to-buy-and-sell-stock-with-transaction-fee |
Medium |
| 238 |
Array |
https://leetcode.com/problems/non-decreasing-array |
Medium |
| 239 |
String, Dynamic Programming |
https://leetcode.com/problems/interleaving-string |
Medium |
| 240 |
Array, Matrix, Simulation |
https://leetcode.com/problems/game-of-life |
Medium |
| 241 |
Array, Backtracking |
https://leetcode.com/problems/combinations |
Medium |
| 242 |
Stack, Tree, Depth-First Search, Binary Tree |
https://leetcode.com/problems/binary-tree-preorder-traversal |
Easy |
| 243 |
Backtracking, Depth-First Search, Breadth-First Search, Graph |
https://leetcode.com/problems/all-paths-from-source-to-target |
Medium |
| 244 |
Array, Math |
https://leetcode.com/problems/plus-one |
Easy |
| 245 |
Array, Dynamic Programming |
https://leetcode.com/problems/best-time-to-buy-and-sell-stock-iv |
Hard |
| 246 |
Array, Greedy |
https://leetcode.com/problems/increasing-triplet-subsequence |
Medium |
| 247 |
Tree, Depth-First Search, Binary Search Tree, Binary Tree |
https://leetcode.com/problems/trim-a-binary-search-tree |
Medium |
| 248 |
Two Pointers, String, Stack, Simulation |
https://leetcode.com/problems/backspace-string-compare |
Easy |
| 249 |
Array, Binary Search, Dynamic Programming, Sliding Window, Rolling Hash, Hash Function |
https://leetcode.com/problems/maximum-length-of-repeated-subarray |
Medium |
| 250 |
Array, Binary Search, Greedy |
https://leetcode.com/problems/capacity-to-ship-packages-within-d-days |
Medium |
| 251 |
Two Pointers, String, String Matching |
https://leetcode.com/problems/implement-strstr |
Easy |
| 252 |
Hash Table, String, Backtracking, Breadth-First Search |
https://leetcode.com/problems/word-ladder-ii |
Hard |
| 253 |
Array, Sliding Window |
https://leetcode.com/problems/subarray-product-less-than-k |
Medium |
| 254 |
Array, Hash Table, Sorting |
https://leetcode.com/problems/contains-duplicate |
Easy |
| 255 |
Linked List, Depth-First Search, Doubly-Linked List |
https://leetcode.com/problems/flatten-a-multilevel-doubly-linked-list |
Medium |
| 256 |
Tree, Depth-First Search, Breadth-First Search, Binary Tree |
https://leetcode.com/problems/populating-next-right-pointers-in-each-node-ii |
Medium |
| 257 |
Array, Divide and Conquer, Stack, Tree, Monotonic Stack, Binary Tree |
https://leetcode.com/problems/maximum-binary-tree |
Medium |
| 258 |
String, Stack |
https://leetcode.com/problems/minimum-remove-to-make-valid-parentheses |
Medium |
| 259 |
Tree, Depth-First Search, Binary Tree |
https://leetcode.com/problems/distribute-coins-in-binary-tree |
Medium |
| 260 |
Depth-First Search, Graph, Biconnected Component |
https://leetcode.com/problems/critical-connections-in-a-network |
Hard |
| 261 |
Math, String, Stack, Recursion |
https://leetcode.com/problems/basic-calculator |
Hard |
| 262 |
Depth-First Search, Breadth-First Search, Union Find, Graph |
https://leetcode.com/problems/redundant-connection |
Medium |
| 263 |
Hash Table, String |
https://leetcode.com/problems/jewels-and-stones |
Easy |
| 264 |
Array, Dynamic Programming, Greedy, Sorting |
https://leetcode.com/problems/non-overlapping-intervals |
Medium |
| 265 |
Array, Depth-First Search, Breadth-First Search, Matrix |
https://leetcode.com/problems/flood-fill |
Easy |
| 266 |
String |
https://leetcode.com/problems/zigzag-conversion |
Medium |
| 267 |
Tree, Depth-First Search, Breadth-First Search, Binary Tree |
https://leetcode.com/problems/maximum-width-of-binary-tree |
Medium |
| 268 |
Math, Recursion |
https://leetcode.com/problems/permutation-sequence |
Hard |
| 269 |
Array, Stack, Tree, Binary Search Tree, Monotonic Stack, Binary Tree |
https://leetcode.com/problems/construct-binary-search-tree-from-preorder-traversal |
Medium |
| 270 |
Math, String, Dynamic Programming, Recursion, Memoization |
https://leetcode.com/problems/different-ways-to-add-parentheses |
Medium |
| 271 |
Array, Binary Search |
https://leetcode.com/problems/search-in-rotated-sorted-array-ii |
Medium |
| 272 |
Linked List, Math, Stack |
https://leetcode.com/problems/add-two-numbers-ii |
Medium |
| 273 |
Hash Table, Two Pointers, Tree, Depth-First Search, Breadth-First Search, Binary Search Tree, Binary Tree |
https://leetcode.com/problems/two-sum-iv-input-is-a-bst |
Easy |
| 274 |
Tree, Depth-First Search, Binary Search Tree, Binary Tree |
https://leetcode.com/problems/convert-bst-to-greater-tree |
Medium |
| 275 |
Linked List, Two Pointers |
https://leetcode.com/problems/partition-list |
Medium |
| 276 |
Math, Binary Search |
https://leetcode.com/problems/sqrtx |
Easy |
| 277 |
Hash Table, String |
https://leetcode.com/problems/isomorphic-strings |
Easy |
| 278 |
Array, Dynamic Programming, Binary Indexed Tree, Segment Tree |
https://leetcode.com/problems/number-of-longest-increasing-subsequence |
Medium |
| 279 |
Array, Binary Search |
https://leetcode.com/problems/binary-search |
Easy |
| 280 |
String, Dynamic Programming, Stack, Greedy |
https://leetcode.com/problems/valid-parenthesis-string |
Medium |
| 281 |
String, String Matching |
https://leetcode.com/problems/repeated-substring-pattern |
Easy |
| 282 |
Array, Two Pointers |
https://leetcode.com/problems/remove-element |
Easy |
| 283 |
Array, Dynamic Programming |
https://leetcode.com/problems/combination-sum-iv |
Medium |
| 284 |
String, Dynamic Programming |
https://leetcode.com/problems/distinct-subsequences |
Hard |
| 285 |
Array, Stack |
https://leetcode.com/problems/asteroid-collision |
Medium |
| 286 |
Array, Math, Dynamic Programming, Sorting |
https://leetcode.com/problems/largest-divisible-subset |
Medium |
| 287 |
Array, Depth-First Search, Breadth-First Search, Matrix |
https://leetcode.com/problems/pacific-atlantic-water-flow |
Medium |
| 288 |
Array, Binary Search, Stack, Monotonic Stack, Ordered Set |
https://leetcode.com/problems/132-pattern |
Medium |
| 289 |
Array, Hash Table, Dynamic Programming |
https://leetcode.com/problems/delete-and-earn |
Medium |
| 290 |
Array, Dynamic Programming, Stack, Monotonic Stack |
https://leetcode.com/problems/sum-of-subarray-minimums |
Medium |
| 291 |
Array, Dynamic Programming, Matrix |
https://leetcode.com/problems/count-square-submatrices-with-all-ones |
Medium |
| 292 |
String, Dynamic Programming |
https://leetcode.com/problems/palindrome-partitioning-ii |
Hard |
| 293 |
Tree, Depth-First Search, Breadth-First Search, Binary Tree |
https://leetcode.com/problems/sum-of-left-leaves |
Easy |
| 294 |
Bit Manipulation |
https://leetcode.com/problems/hamming-distance |
Easy |
| 295 |
Stack, Tree, Depth-First Search, Design, Queue, Iterator |
https://leetcode.com/problems/flatten-nested-list-iterator |
Medium |
| 296 |
String, Stack |
https://leetcode.com/problems/score-of-parentheses |
Medium |
| 297 |
Array, Hash Table, Two Pointers, String, Dynamic Programming |
https://leetcode.com/problems/longest-string-chain |
Medium |
| 298 |
Two Pointers, String |
https://leetcode.com/problems/valid-palindrome |
Easy |
| 299 |
Tree, Depth-First Search, Binary Tree |
https://leetcode.com/problems/longest-univalue-path |
Medium |
| 300 |
String, Backtracking, Bit Manipulation |
https://leetcode.com/problems/letter-case-permutation |
Medium |
| 301 |
Tree, Breadth-First Search, Binary Tree |
https://leetcode.com/problems/binary-tree-level-order-traversal-ii |
Medium |
| 302 |
Tree, Depth-First Search, Breadth-First Search, Binary Tree |
https://leetcode.com/problems/find-duplicate-subtrees |
Medium |
| 303 |
Dynamic Programming, Stack, Greedy, Monotonic Stack |
https://leetcode.com/problems/minimum-cost-tree-from-leaf-values |
Medium |
| 304 |
Hash Table, Linked List, Design, Doubly-Linked List |
https://leetcode.com/problems/lfu-cache |
Hard |
| 305 |
Array, Binary Search, Dynamic Programming, Sorting |
https://leetcode.com/problems/russian-doll-envelopes |
Hard |
| 306 |
Array, Binary Search, Dynamic Programming, Sorting |
https://leetcode.com/problems/maximum-profit-in-job-scheduling |
Hard |
| 307 |
Math, String, Simulation |
https://leetcode.com/problems/add-strings |
Easy |
| 308 |
Array, Hash Table, Counting |
https://leetcode.com/problems/pairs-of-songs-with-total-durations-divisible-by-60 |
Medium |
| 309 |
Stack, Design, Queue |
https://leetcode.com/problems/implement-queue-using-stacks |
Easy |
| 310 |
Array, Hash Table, Bit Manipulation, Trie |
https://leetcode.com/problems/maximum-xor-of-two-numbers-in-an-array |
Medium |
| 311 |
Hash Table, Math, String |
https://leetcode.com/problems/roman-to-integer |
Easy |
| 312 |
Array, Hash Table, Graph |
https://leetcode.com/problems/find-the-town-judge |
Easy |
| 313 |
Array, Heap (Priority Queue) |
https://leetcode.com/problems/find-k-pairs-with-smallest-sums |
Medium |
| 314 |
Array, Two Pointers, Sorting |
https://leetcode.com/problems/merge-sorted-array |
Easy |
| 315 |
String, Stack |
https://leetcode.com/problems/remove-all-adjacent-duplicates-in-string |
Easy |
| 316 |
Two Pointers, String |
https://leetcode.com/problems/reverse-words-in-a-string |
Medium |
| 317 |
Array, Hash Table |
https://leetcode.com/problems/4sum-ii |
Medium |
| 318 |
Tree, Depth-First Search, Breadth-First Search, Binary Tree |
https://leetcode.com/problems/average-of-levels-in-binary-tree |
Easy |
| 319 |
Array, Prefix Sum |
https://leetcode.com/problems/find-pivot-index |
Easy |
| 320 |
Array, Hash Table, Sorting, Counting |
https://leetcode.com/problems/how-many-numbers-are-smaller-than-the-current-number |
Easy |
| 321 |
Hash Table, Math, String |
https://leetcode.com/problems/integer-to-roman |
Medium |
| 322 |
Depth-First Search, Breadth-First Search, Graph |
https://leetcode.com/problems/keys-and-rooms |
Medium |
| 323 |
Math, Bit Manipulation, Recursion |
https://leetcode.com/problems/power-of-two |
Easy |
| 324 |
Array, Hash Table, Sliding Window, Counting |
https://leetcode.com/problems/subarrays-with-k-different-integers |
Hard |
| 325 |
Array, Math, Dynamic Programming, Recursion, Game Theory |
https://leetcode.com/problems/predict-the-winner |
Medium |
| 326 |
Array, Divide and Conquer, Dynamic Programming, Queue, Monotonic Queue |
https://leetcode.com/problems/maximum-sum-circular-subarray |
Medium |
| 327 |
Math, Dynamic Programming, Recursion, Memoization |
https://leetcode.com/problems/fibonacci-number |
Easy |
| 328 |
Divide and Conquer, Bit Manipulation |
https://leetcode.com/problems/reverse-bits |
Easy |
| 329 |
Tree, Depth-First Search, Binary Tree |
https://leetcode.com/problems/delete-nodes-and-return-forest |
Medium |
| 330 |
Array, Binary Search, Queue, Sliding Window, Heap (Priority Queue), Prefix Sum, Monotonic Queue |
https://leetcode.com/problems/shortest-subarray-with-sum-at-least-k |
Hard |
| 331 |
Array, Binary Search |
https://leetcode.com/problems/find-minimum-in-rotated-sorted-array-ii |
Hard |
| 332 |
Hash Table, String |
https://leetcode.com/problems/word-pattern |
Easy |
| 333 |
Array, Dynamic Programming |
https://leetcode.com/problems/arithmetic-slices |
Medium |
| 334 |
Array, String, Dynamic Programming |
https://leetcode.com/problems/ones-and-zeroes |
Medium |
| 335 |
Array, Backtracking, Bit Manipulation, Matrix |
https://leetcode.com/problems/unique-paths-iii |
Hard |
| 336 |
Array, Design, Binary Indexed Tree, Segment Tree |
https://leetcode.com/problems/range-sum-query-mutable |
Medium |
| 337 |
Hash Table, Tree, Depth-First Search, Breadth-First Search, Binary Tree |
https://leetcode.com/problems/vertical-order-traversal-of-a-binary-tree |
Hard |
| 338 |
Array, Greedy |
https://leetcode.com/problems/candy |
Hard |
| 339 |
Array, Two Pointers |
https://leetcode.com/problems/remove-duplicates-from-sorted-array-ii |
Medium |
| 340 |
Hash Table, String, Trie, Sorting |
https://leetcode.com/problems/number-of-matching-subsequences |
Medium |
| 341 |
Array, Binary Search |
https://leetcode.com/problems/koko-eating-bananas |
Medium |
| 342 |
Array, Hash Table, String, Breadth-First Search |
https://leetcode.com/problems/open-the-lock |
Medium |
| 343 |
String, Tree, Depth-First Search, Breadth-First Search, Design, Binary Search Tree, Binary Tree |
https://leetcode.com/problems/serialize-and-deserialize-bst |
Medium |
| 344 |
Array, Backtracking |
https://leetcode.com/problems/combination-sum-iii |
Medium |
| 345 |
Array, Hash Table, String, Trie |
https://leetcode.com/problems/palindrome-pairs |
Hard |
| 346 |
Array, Hash Table, String |
https://leetcode.com/problems/verifying-an-alien-dictionary |
Easy |
| 347 |
Array, Math, Stack |
https://leetcode.com/problems/evaluate-reverse-polish-notation |
Medium |
| 348 |
Array, Breadth-First Search, Heap (Priority Queue), Matrix |
https://leetcode.com/problems/trapping-rain-water-ii |
Hard |
| 349 |
Array, Sliding Window, Prefix Sum |
https://leetcode.com/problems/maximum-points-you-can-obtain-from-cards |
Medium |
| 350 |
Tree, Depth-First Search, Breadth-First Search, Binary Tree |
https://leetcode.com/problems/cousins-in-binary-tree |
Easy |
| 351 |
Math, Bit Manipulation |
https://leetcode.com/problems/divide-two-integers |
Medium |
| 352 |
String, Dynamic Programming |
https://leetcode.com/problems/delete-operation-for-two-strings |
Medium |
| 353 |
Array, Greedy, Sorting |
https://leetcode.com/problems/minimum-number-of-arrows-to-burst-balloons |
Medium |
| 354 |
Array, Hash Table, Prefix Sum |
https://leetcode.com/problems/subarray-sums-divisible-by-k |
Medium |
| 355 |
Two Pointers, String |
https://leetcode.com/problems/count-binary-substrings |
Easy |
| 356 |
String, Backtracking |
https://leetcode.com/problems/restore-ip-addresses |
Medium |
| 357 |
Array, Matrix, Simulation |
https://leetcode.com/problems/spiral-matrix-ii |
Medium |
| 358 |
Hash Table, Stack, Design, Ordered Set |
https://leetcode.com/problems/maximum-frequency-stack |
Hard |
| 359 |
Math, Dynamic Programming |
https://leetcode.com/problems/integer-break |
Medium |
| 360 |
Array, Two Pointers, Sorting |
https://leetcode.com/problems/sort-array-by-parity |
Easy |
| 361 |
Dynamic Programming, Tree, Depth-First Search, Binary Tree |
https://leetcode.com/problems/binary-tree-cameras |
Hard |
| 362 |
Array, Dynamic Programming, Greedy |
https://leetcode.com/problems/wiggle-subsequence |
Medium |
| 363 |
Array, Depth-First Search, Breadth-First Search |
https://leetcode.com/problems/jump-game-iii |
Medium |
| 364 |
Bit Manipulation |
https://leetcode.com/problems/number-of-1-bits |
Easy |
| 365 |
Tree, Binary Search Tree, Binary Tree |
https://leetcode.com/problems/insert-into-a-binary-search-tree |
Medium |
| 366 |
Array, Math, Sorting |
https://leetcode.com/problems/maximum-product-of-three-numbers |
Easy |
| 367 |
Math, String, Backtracking |
https://leetcode.com/problems/expression-add-operators |
Hard |
| 368 |
Math, String |
https://leetcode.com/problems/excel-sheet-column-title |
Easy |
| 369 |
Array, Binary Search, Divide and Conquer, Binary Indexed Tree, Segment Tree, Merge Sort, Ordered Set |
https://leetcode.com/problems/reverse-pairs |
Hard |
| 370 |
Dynamic Programming, Tree, Depth-First Search, Graph |
https://leetcode.com/problems/sum-of-distances-in-tree |
Hard |
| 371 |
Array, Greedy, Sorting |
https://leetcode.com/problems/two-city-scheduling |
Medium |
| 372 |
String, Stack |
https://leetcode.com/problems/remove-all-adjacent-duplicates-in-string-ii |
Medium |
| 373 |
Array, Design, Matrix, Prefix Sum |
https://leetcode.com/problems/range-sum-query-2d-immutable |
Medium |
| 374 |
Math, Dynamic Programming |
https://leetcode.com/problems/2-keys-keyboard |
Medium |
| 375 |
Array, Hash Table, Two Pointers, Binary Search, Sorting |
https://leetcode.com/problems/intersection-of-two-arrays |
Easy |
| 376 |
Array, Stack, Simulation |
https://leetcode.com/problems/validate-stack-sequences |
Medium |
| 377 |
Hash Table, String, Greedy |
https://leetcode.com/problems/longest-palindrome |
Easy |
| 378 |
Tree, Binary Search Tree, Binary Tree |
https://leetcode.com/problems/search-in-a-binary-search-tree |
Easy |
| 379 |
Array, Dynamic Programming, Greedy, Heap (Priority Queue) |
https://leetcode.com/problems/minimum-number-of-refueling-stops |
Hard |
| 380 |
Array, Two Pointers, Binary Search, Greedy, Sorting |
https://leetcode.com/problems/valid-triangle-number |
Medium |
| 381 |
Dynamic Programming, Tree, Recursion, Memoization, Binary Tree |
https://leetcode.com/problems/all-possible-full-binary-trees |
Medium |
| 382 |
Two Pointers, String |
https://leetcode.com/problems/reverse-words-in-a-string-iii |
Easy |
| 383 |
Math, String |
https://leetcode.com/problems/excel-sheet-column-number |
Easy |
| 384 |
Array, Dynamic Programming, Matrix |
https://leetcode.com/problems/cherry-pickup |
Hard |
| 385 |
Array, Hash Table, Linked List, Design, Hash Function |
https://leetcode.com/problems/design-hashmap |
Easy |
| 386 |
Tree, Depth-First Search, Binary Tree |
https://leetcode.com/problems/binary-tree-pruning |
Medium |
| 387 |
Math, Bit Manipulation |
https://leetcode.com/problems/sum-of-two-integers |
Medium |
| 388 |
Stack, Design, Monotonic Stack, Data Stream |
https://leetcode.com/problems/online-stock-span |
Medium |
| 389 |
Linked List, Math |
https://leetcode.com/problems/convert-binary-number-in-a-linked-list-to-integer |
Easy |
| 390 |
Tree, Depth-First Search, Binary Search Tree, Binary Tree |
https://leetcode.com/problems/binary-search-tree-to-greater-sum-tree |
Medium |
| 391 |
Array |
https://leetcode.com/problems/max-consecutive-ones |
Easy |
| 392 |
Array, Prefix Sum |
https://leetcode.com/problems/running-sum-of-1d-array |
Easy |
| 393 |
Math, Greedy |
https://leetcode.com/problems/maximum-swap |
Medium |
| 394 |
String, Rolling Hash, String Matching, Hash Function |
https://leetcode.com/problems/shortest-palindrome |
Hard |
| 395 |
Depth-First Search, Union Find, Graph |
https://leetcode.com/problems/most-stones-removed-with-same-row-or-column |
Medium |
| 396 |
Tree, Depth-First Search, Binary Tree |
https://leetcode.com/problems/maximum-difference-between-node-and-ancestor |
Medium |
| 397 |
Array, Dynamic Programming |
https://leetcode.com/problems/frog-jump |
Hard |
| 398 |
Array, Dynamic Programming |
https://leetcode.com/problems/pascals-triangle-ii |
Easy |
| 399 |
Tree, Depth-First Search, Breadth-First Search, Binary Tree |
https://leetcode.com/problems/deepest-leaves-sum |
Medium |
| 400 |
Array, Depth-First Search, Breadth-First Search, Matrix |
https://leetcode.com/problems/shortest-bridge |
Medium |
| 401 |
Bit Manipulation |
https://leetcode.com/problems/bitwise-and-of-numbers-range |
Medium |
| 402 |
Math, Binary Search, Dynamic Programming |
https://leetcode.com/problems/super-egg-drop |
Hard |
| 403 |
Array, Sliding Window, Sorting, Bucket Sort, Ordered Set |
https://leetcode.com/problems/contains-duplicate-iii |
Medium |
| 404 |
Math, String, Simulation |
https://leetcode.com/problems/robot-bounded-in-circle |
Medium |
| 405 |
Stack, Tree, Depth-First Search, Binary Search Tree, Binary Tree |
https://leetcode.com/problems/increasing-order-search-tree |
Easy |
| 406 |
Array, Hash Table, String |
https://leetcode.com/problems/find-common-characters |
Easy |
| 407 |
Array, Two Pointers, String |
https://leetcode.com/problems/shortest-distance-to-a-character |
Easy |
| 408 |
Array, Greedy |
https://leetcode.com/problems/can-place-flowers |
Easy |
| 409 |
Array, Hash Table, Sliding Window |
https://leetcode.com/problems/contains-duplicate-ii |
Easy |
| 410 |
Array, Hash Table, Math, Counting |
https://leetcode.com/problems/number-of-good-pairs |
Easy |
| 411 |
String, Stack, Greedy |
https://leetcode.com/problems/minimum-add-to-make-parentheses-valid |
Medium |
| 412 |
Array, Dynamic Programming, Greedy, Sorting |
https://leetcode.com/problems/maximum-length-of-pair-chain |
Medium |
| 413 |
Depth-First Search, Breadth-First Search, Union Find, Graph |
https://leetcode.com/problems/possible-bipartition |
Medium |
| 414 |
Array, Hash Table, Greedy, Heap (Priority Queue) |
https://leetcode.com/problems/split-array-into-consecutive-subsequences |
Medium |
| 415 |
Array, Depth-First Search, Breadth-First Search, Union Find, Matrix |
https://leetcode.com/problems/making-a-large-island |
Hard |
| 416 |
Array, Breadth-First Search, Matrix |
https://leetcode.com/problems/shortest-path-in-binary-matrix |
Medium |
| 417 |
Tree, Depth-First Search, Breadth-First Search, Binary Tree |
https://leetcode.com/problems/count-good-nodes-in-binary-tree |
Medium |
| 418 |
Array |
https://leetcode.com/problems/shuffle-the-array |
Easy |
| 419 |
Array, Hash Table, Sliding Window, Heap (Priority Queue) |
https://leetcode.com/problems/sliding-window-median |
Hard |
| 420 |
Array, Binary Search |
https://leetcode.com/problems/kth-missing-positive-number |
Easy |
| 421 |
Array, Binary Search |
https://leetcode.com/problems/peak-index-in-a-mountain-array |
Easy |
| 422 |
Array, Linked List, Stack, Monotonic Stack |
https://leetcode.com/problems/next-greater-node-in-linked-list |
Medium |
| 423 |
Array, Dynamic Programming |
https://leetcode.com/problems/minimum-swaps-to-make-sequences-increasing |
Hard |
| 424 |
Array, Divide and Conquer, Sorting, Quickselect |
https://leetcode.com/problems/wiggle-sort-ii |
Medium |
| 425 |
Array, Hash Table, Greedy, Sliding Window, Sorting, Heap (Priority Queue) |
https://leetcode.com/problems/smallest-range-covering-elements-from-k-lists |
Hard |
| 426 |
Math, String, Recursion |
https://leetcode.com/problems/integer-to-english-words |
Hard |
| 427 |
Array, Dynamic Programming |
https://leetcode.com/problems/partition-array-for-maximum-sum |
Medium |
| 428 |
Array, Sorting, Bucket Sort, Radix Sort |
https://leetcode.com/problems/maximum-gap |
Hard |
| 429 |
Tree, Depth-First Search, Binary Search Tree, Binary Tree |
https://leetcode.com/problems/find-mode-in-binary-search-tree |
Easy |
| 430 |
Array, Hash Table, Binary Search, Dynamic Programming |
https://leetcode.com/problems/longest-arithmetic-subsequence |
Medium |
| 431 |
Array, Dynamic Programming |
https://leetcode.com/problems/last-stone-weight-ii |
Medium |
| 432 |
Array, Heap (Priority Queue) |
https://leetcode.com/problems/last-stone-weight |
Easy |
| 433 |
Tree, Depth-First Search, Breadth-First Search, Binary Tree |
https://leetcode.com/problems/find-bottom-left-tree-value |
Medium |
| 434 |
Depth-First Search, Breadth-First Search, Union Find, Graph |
https://leetcode.com/problems/regions-cut-by-slashes |
Medium |
| 435 |
Array, Dynamic Programming, Backtracking, Bit Manipulation, Bitmask |
https://leetcode.com/problems/beautiful-arrangement |
Medium |
| 436 |
Array, Dynamic Programming, Matrix |
https://leetcode.com/problems/minimum-falling-path-sum |
Medium |
| 437 |
Array, Matrix, Simulation |
https://leetcode.com/problems/diagonal-traverse |
Medium |
| 438 |
Array, Queue, Sliding Window, Heap (Priority Queue), Ordered Set, Monotonic Queue |
https://leetcode.com/problems/longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit |
Medium |
| 439 |
Bit Manipulation |
https://leetcode.com/problems/number-complement |
Easy |
| 440 |
Math, Binary Search |
https://leetcode.com/problems/valid-perfect-square |
Easy |
| 441 |
Math, Binary Search |
https://leetcode.com/problems/arranging-coins |
Easy |
| 442 |
Math, Two Pointers, String |
https://leetcode.com/problems/next-greater-element-iii |
Medium |
| 443 |
Array, Binary Search, Depth-First Search, Breadth-First Search, Union Find, Heap (Priority Queue), Matrix |
https://leetcode.com/problems/path-with-minimum-effort |
Medium |
| 444 |
Array, String, Trie |
https://leetcode.com/problems/search-suggestions-system |
Medium |
| 445 |
Array, Two Pointers, Matrix, Simulation |
https://leetcode.com/problems/flipping-an-image |
Easy |
| 446 |
Tree, Design, Binary Search Tree, Heap (Priority Queue), Binary Tree, Data Stream |
https://leetcode.com/problems/kth-largest-element-in-a-stream |
Easy |
| 447 |
Array, Binary Search, Dynamic Programming, Matrix, Ordered Set |
https://leetcode.com/problems/max-sum-of-rectangle-no-larger-than-k |
Hard |
| 448 |
Hash Table, String, Binary Search, Design |
https://leetcode.com/problems/time-based-key-value-store |
Medium |
| 449 |
Linked List, Sorting |
https://leetcode.com/problems/insertion-sort-list |
Medium |
| 450 |
Two Pointers, String |
https://leetcode.com/problems/string-compression |
Medium |
| 451 |
Tree, Depth-First Search, Breadth-First Search |
https://leetcode.com/problems/maximum-depth-of-n-ary-tree |
Easy |
| 452 |
Math |
https://leetcode.com/problems/factorial-trailing-zeroes |
Medium |
| 453 |
Array, Sorting, Heap (Priority Queue), Simulation, Prefix Sum |
https://leetcode.com/problems/car-pooling |
Medium |
| 454 |
Tree, Depth-First Search, Breadth-First Search, Binary Tree |
https://leetcode.com/problems/find-largest-value-in-each-tree-row |
Medium |
| 455 |
String, Dynamic Programming |
https://leetcode.com/problems/shortest-common-supersequence |
Hard |
| 456 |
Dynamic Programming |
https://leetcode.com/problems/number-of-dice-rolls-with-target-sum |
Medium |
| 457 |
Hash Table, Linked List, Design, Heap (Priority Queue) |
https://leetcode.com/problems/design-twitter |
Medium |
| 458 |
Array, Depth-First Search |
https://leetcode.com/problems/array-nesting |
Medium |
| 459 |
Array, Math, Dynamic Programming, Game Theory |
https://leetcode.com/problems/stone-game |
Medium |
| 460 |
Array, Hash Table |
https://leetcode.com/problems/degree-of-an-array |
Easy |
| 461 |
Hash Table, String, Bit Manipulation, Sorting |
https://leetcode.com/problems/find-the-difference |
Easy |
| 462 |
Tree, Depth-First Search, Breadth-First Search, Binary Search Tree, Binary Tree |
https://leetcode.com/problems/minimum-absolute-difference-in-bst |
Easy |
| 463 |
Array, Binary Search, Matrix |
https://leetcode.com/problems/count-negative-numbers-in-a-sorted-matrix |
Easy |
| 464 |
Array, Greedy, Heap (Priority Queue) |
https://leetcode.com/problems/course-schedule-iii |
Hard |
| 465 |
Hash Table, Tree, Depth-First Search, Breadth-First Search, Binary Tree |
https://leetcode.com/problems/smallest-subtree-with-all-the-deepest-nodes |
Medium |
| 466 |
Array, Matrix, Simulation |
https://leetcode.com/problems/reshape-the-matrix |
Easy |
| 467 |
Array, Matrix |
https://leetcode.com/problems/toeplitz-matrix |
Easy |
| 468 |
Dynamic Programming |
https://leetcode.com/problems/knight-probability-in-chessboard |
Medium |
| 469 |
Array, Two Pointers, Binary Search, Sorting |
https://leetcode.com/problems/find-k-th-smallest-pair-distance |
Hard |
| 470 |
Design, Segment Tree, Ordered Set |
https://leetcode.com/problems/my-calendar-i |
Medium |
| 471 |
String, Dynamic Programming |
https://leetcode.com/problems/minimum-ascii-delete-sum-for-two-strings |
Medium |
| 472 |
Array, Breadth-First Search, Matrix |
https://leetcode.com/problems/shortest-path-in-a-grid-with-obstacles-elimination |
Hard |
| 473 |
Array, Design, Prefix Sum |
https://leetcode.com/problems/range-sum-query-immutable |
Easy |
| 474 |
Tree, Breadth-First Search, Binary Tree |
https://leetcode.com/problems/check-completeness-of-a-binary-tree |
Medium |
| 475 |
Array |
https://leetcode.com/problems/maximize-distance-to-closest-person |
Medium |
| 476 |
Stack, Design, Queue |
https://leetcode.com/problems/implement-stack-using-queues |
Easy |
| 477 |
Math, Dynamic Programming, Bit Manipulation, Memoization, Game Theory, Bitmask |
https://leetcode.com/problems/can-i-win |
Medium |
| 478 |
Hash Table, String, Sorting |
https://leetcode.com/problems/custom-sort-string |
Medium |
| 479 |
Array, Hash Table |
https://leetcode.com/problems/brick-wall |
Medium |
| 480 |
Array, Hash Table, Stack, Monotonic Stack |
https://leetcode.com/problems/next-greater-element-i |
Easy |
| 481 |
Tree, Depth-First Search, Binary Tree |
https://leetcode.com/problems/sum-of-root-to-leaf-binary-numbers |
Easy |
| 482 |
Depth-First Search, Breadth-First Search, Graph, Topological Sort |
https://leetcode.com/problems/find-eventual-safe-states |
Medium |
| 483 |
Array, Queue, Sorting, Simulation |
https://leetcode.com/problems/reveal-cards-in-increasing-order |
Medium |
| 484 |
Array, String, Dynamic Programming, Depth-First Search, Trie |
https://leetcode.com/problems/concatenated-words |
Hard |
| 485 |
Array, Two Pointers, Greedy, Sorting |
https://leetcode.com/problems/boats-to-save-people |
Medium |
| 486 |
Array, Hash Table, Divide and Conquer, Tree, Binary Tree |
https://leetcode.com/problems/construct-binary-tree-from-preorder-and-postorder-traversal |
Medium |
| 487 |
Array, Dynamic Programming, Binary Indexed Tree |
https://leetcode.com/problems/count-number-of-teams |
Medium |
| 488 |
Hash Table, String, Bit Manipulation, Sliding Window, Rolling Hash, Hash Function |
https://leetcode.com/problems/repeated-dna-sequences |
Medium |
| 489 |
Hash Table, String, Sliding Window |
https://leetcode.com/problems/substring-with-concatenation-of-all-words |
Hard |
| 490 |
Array, Hash Table, Breadth-First Search |
https://leetcode.com/problems/bus-routes |
Hard |
| 491 |
Array, Hash Table, String |
https://leetcode.com/problems/find-and-replace-pattern |
Medium |
| 492 |
Array, Binary Search, Depth-First Search, Breadth-First Search, Union Find, Heap (Priority Queue), Matrix |
https://leetcode.com/problems/swim-in-rising-water |
Hard |
| 493 |
Depth-First Search, Breadth-First Search, Union Find, Graph |
https://leetcode.com/problems/number-of-operations-to-make-network-connected |
Medium |
| 494 |
Array, Divide and Conquer, Sorting, Heap (Priority Queue), Merge Sort, Bucket Sort, Radix Sort, Counting Sort |
https://leetcode.com/problems/sort-an-array |
Medium |
| 495 |
Array, Backtracking, Matrix |
https://leetcode.com/problems/path-with-maximum-gold |
Medium |
| 496 |
Array, Hash Table, Bit Manipulation, Sorting |
https://leetcode.com/problems/set-mismatch |
Easy |
| 497 |
Linked List |
https://leetcode.com/problems/split-linked-list-in-parts |
Medium |
| 498 |
Array, Two Pointers, Dynamic Programming, Enumeration |
https://leetcode.com/problems/longest-mountain-in-array |
Medium |
| 499 |
String, String Matching |
https://leetcode.com/problems/rotate-string |
Easy |
| 500 |
Array, Hash Table, String |
https://leetcode.com/problems/unique-email-addresses |
Easy |
0