| 1 |
Two Sum |
Easy |
O(N) |
O(N) |
|
|
|
| 7 |
Reverse Integer |
Easy |
O(log x) |
O(1) |
|
Tricky |
|
| 11 |
Container With Most Water |
Medium |
O(N) |
O(1) |
Array, Two Pointers, Greedy |
|
|
| 12 |
Integer to Roman |
Medium |
O(N) |
O(N) |
Math, String |
|
|
| 13 |
Roman to Integer |
Easy |
O(N) |
O(1) |
Math, String |
|
|
| 15 |
3Sum |
Medium |
O(N^2) |
O(N^2) |
Array, Two Pointers |
|
|
| 17 |
Letter Combinations of a Phone Number |
Medium |
O(2^2) |
O(2^N) |
String, Backtracking, DFS, Recursion |
|
|
| 19 |
Remove Nth Node From End of List |
Medium |
O(N) |
O(1) |
Linked List, Two Pointers |
|
|
| 20 |
Valid Parentheses |
Easy |
O(N) |
O(N) |
String, Stack |
|
|
| 21 |
Merge Two Sorted Lists |
Easy |
O(N) |
O(1) |
Linked List |
|
|
| 22 |
Generate Parentheses |
Medium |
Complex |
Complex |
String, Backtracking |
|
|
| 24 |
Swap Nodes in Pairs |
Medium |
O(N) |
O(N) |
Linked List |
|
|
| 25 |
Reverse Nodes in k-Group |
Hard |
O(N) |
O(1) |
Linked List, Recursion |
|
|
| 30 |
Substring with Concatenation of All Words |
Hard |
O(NK) |
O(K) |
Array, Backtracking |
|
|
| 32 |
Longest Valid Parentheses |
Hard |
O(N) |
O(N) |
String, Dynamic Programming |
|
|
| 34 |
Find First and Last Position of Element in Sorted Array |
Medium |
O(logN) |
O(1) |
Array, Binary Search |
Template for Binary Search |
|
| 39 |
Combination Sum |
Medium |
O(N^2) |
O(N) |
Array, Backtracking |
|
|
| 42 |
Trapping Rain Water |
Hard |
O(N) |
O(N) |
Array, Two Pointers, Dynamic Programming, Stack |
|
|
| 45 |
Jump Game II |
Medium |
O(N) |
O(1) |
Array, Greedy |
|
|
| 46 |
Permutations |
Medium |
O(N!) |
O(N!) |
Backtracking |
|
|
| 47 |
Permutations II |
Medium |
O(N!) |
O(N!) |
Backtracking |
|
|
| 48 |
Rotate Image |
Medium |
O(N*M) |
O(1) |
Array |
|
|
| 51 |
N-Queens |
Hard |
O(N!) |
O(N^2) |
Backtracking |
|
|
| 51 |
N-Queens II |
Hard |
O(N!) |
O(N^2) |
Backtracking |
|
|
| 53 |
Maximum Subarray |
Easy |
O(N) |
O(1) |
|
|
|
| 57 |
Insert Interval |
Hard |
O(N) |
O(N) |
Array, Sort, Greedy |
|
|
| 59 |
Spiral Matrix II |
Medium |
O(N^2) |
O(N^2) |
Array |
|
|
| 61 |
Rotate List |
Medium |
O(N) |
O(1) |
Linked List, Two Pointers |
|
|
| 63 |
Unique Paths II |
Medium |
O(M*N) |
O(M) |
Array, Dynamic Programming |
|
|
| 71 |
Simplify Path |
Medium |
O(N) |
O(N) |
String, Stack |
|
|
| 72 |
Edit Distance |
Hard |
O(N*M) |
O(N) |
String, Dynamic Programming |
|
|
| 74 |
Search a 2D Matrix |
Medium |
O(logN + logM) |
O(1) |
Binary Search |
|
|
| 76 |
Minimum Window Substring |
Hard |
O(S+T) |
O(S+T) |
Hash Table, Two Pointers, String, Sliding Window |
|
|
| 78 |
Subsets |
Medium |
O(N*2^N) |
O(N*2^N) |
Backtracking, Bit Manipulation |
|
|
| 80 |
Remove Duplicates from Sorted Array II |
Medium |
O(N) |
O(1) |
Array, Two Pointers |
|
|
| 82 |
Remove Duplicates from Sorted List II |
Medium |
O(N) |
O(1) |
Linked List |
|
|
| 84 |
Largest Rectangle in Histogram |
Hard |
O(N) |
O(N) |
Array, Stack, Monotonic Stack |
|
|
| 85 |
Maximal Rectangle |
Hard |
O(R*C*C) |
O(C) |
Array, Dynamic Programming, Stack, Matrix, Monotonic Stack |
|
|
| 89 |
Gray Code |
Medium |
O(2^N) |
O(2^N) |
Math, Backtracking, Bit Manipulation |
|
|
| 91 |
Decode Ways |
Medium |
O(N) |
O(N) |
String, Dynamic Programming |
|
|
| 92 |
Reverse Linked List II |
Medium |
O(N) |
O(1) |
Linked List |
|
|
| 94 |
Binary Tree Inorder Traversal |
Easy |
O(N) |
O(N) |
Stack, Tree, DFS, Binary Tree |
|
|
| 99 |
Recover Binary Search Tree |
Hard |
O(N) |
O(N) |
Tree, DFS |
|
|
| 100 |
Same Tree |
Easy |
O(N) |
O(H) |
Tree, Pythonic |
|
|
| 102 |
Binary Tree Level Order Traversal |
Medium |
O(N) |
O(N) |
Tree, BFS |
|
|
| 104 |
Maximum Depth of Binary Tree |
Easy |
O(N) |
O(N) |
Tree, BFS, DFS |
|
|
| 105 |
Construct Binary Tree from Preorder and Inorder Traversal |
Medium |
O(N) |
O(N) |
Array, Tree, DFS |
|
|
| 106 |
Construct Binary Tree from Inorder and Postorder Traversal |
Medium |
O(N) |
O(N) |
Array, Hash Table, Divide and Conquer, Tree, Binary Tree |
|
|
| 107 |
Binary Tree Level Order Traversal II |
Easy |
O(N) |
O(N) |
Tree, BFS |
|
|
| 111 |
Minimum Depth of Binary Tree |
Easy |
O(N) |
O(H) |
Tree, DFS, BFS |
|
|
| 114 |
Flatten Binary Tree to Linked List |
Medium |
O(N) |
O(1) |
Tree, DFS |
|
|
| 115 |
Distinct Subsequences |
Medium |
O(N) |
O(1) |
String, Dynamic Programming |
|
|
| 116 |
Populating Next Right Pointers in Each Node |
Medium |
O(N) |
O(N) |
Tree, DFS, BFS |
|
|
| 119 |
Pascal's Triangle II |
Easy |
O(k^2) |
O(k) |
Array |
|
|
| 121 |
Best Time to Buy and Sell Stock |
Easy |
O(N) |
O(1) |
Dynamic Programming |
|
|
| 122 |
Best Time to Buy and Sell Stock II |
Easy |
O(N) |
O(1) |
Array, Greedy |
|
|
| 125 |
Valid Palindrome |
Easy |
O(1) |
O(1) |
String |
|
|
| 127 |
Word Ladder |
Hard |
O(M^2*N) |
O(M^2*N) |
BFS |
|
|
| 128 |
Longest Consecutive Sequence |
Medium |
O(N) |
O(N) |
Array |
|
|
| 130 |
Surrounded Regions |
Medium |
O(N*M) |
O(N*M) |
Array, BFS, DFS, Union Find, Matrix |
|
|
| 131 |
Palindrome Partitioning |
Medium |
O(N*2^N) |
O(N*N) |
String, Dynamic Programming, Backtracking |
|
|
| 133 |
Clone Graph |
Medium |
O(N+M) |
O(N) |
DFS, BFS, Graph |
|
|
| 134 |
Gas Station |
Medium |
O(N) |
O(N) |
Dynamic Programming, Greedy |
|
|
| 135 |
Candy |
Hard |
O(N) |
O(N) |
Greedy |
|
|
| 138 |
Copy List with Random Pointer |
Medium |
O(N) |
O(N) |
Hash Table, Linked List |
|
|
| 139 |
Word Break |
Medium |
O(N^2) |
O(N) |
Dynamic Programming |
|
|
| 141 |
Linked List Cycle |
Easy |
O(N) |
O(1) |
Linked List, Two Pointers |
|
|
| 142 |
Linked List Cycle II |
Medium |
O(N) |
O(1) |
Linked List, Two Pointers |
|
|
| 143 |
Reorder List |
Medium |
O(N) |
O(1) |
Linked List |
|
|
| 144 |
Binary Tree Preorder Traversal |
Easy |
O(N) |
O(N) |
Stack, Tree, DFS, Binary Tree |
|
|
| 145 |
Binary Tree Postorder Traversal |
Easy |
O(N) |
O(N) |
Stack, Tree, DFS, Binary Tree |
|
|
| 146 |
LRU Cache |
Medium |
Design |
Design |
Hash Table, Linked List, Design, Doubly-Linked List |
|
|
| 147 |
Insertion Sort List |
Medium |
O(N^2) |
O(1) |
Sort, Linked List |
|
|
| 151 |
Evaluate Reverse Polish Notation |
Medium |
O(N) |
O(N) |
Stack |
|
|
| 151 |
Reverse Words in a String |
Easy |
O(N) |
O(N) |
String |
|
|
| 152 |
Maximum Product Subarray |
Medium |
O(N) |
O(N) |
Dynamic Programming, Array |
|
|
| 153 |
Find Minimum in Rotated Sorted Array |
Medium |
O(logN) |
O(1) |
Binary Search |
|
|
| 154 |
Find Minimum in Rotated Sorted Array II |
Hard |
O(logN) |
O(1) |
Binary Search |
|
|
| 159 |
Longest Substring with At Most Two Distinct Characters |
Medium |
O(N) |
O(1) |
Premium, Hash Table, Two Pointers, String, Sliding Window |
|
|
| 165 |
Compare Version Numbers |
Medium |
O(N) |
O(1) |
String |
|
|
| 168 |
Excel Sheet Column Title |
Medium |
O(logN) |
O(logN) |
Math |
Math Tricks |
|
| 171 |
Excel Sheet Column Number |
Easy |
O(N) |
O(1) |
String |
|
|
| 175 |
Combine Two Tables |
Easy |
N/A |
N/A |
Database |
|
|
| 178 |
Rank Scores |
Medium |
N/A |
N/A |
Database |
|
|
| 179 |
Largest Number |
Medium |
O(NlogN) |
O(1) |
Sort |
|
|
| 182 |
Duplicate Emails |
Easy |
N/A |
N/A |
Database |
|
|
| 183 |
Customers Who Never Order |
Easy |
N/A |
N/A |
Database |
|
|
| 187 |
Repeated DNA Sequences |
Medium |
O(N-L) |
O(N-L) |
Hash Table, Bit Manipulation |
|
|
| 190 |
Reverse Bits |
Easy |
O(1) |
O(1) |
Bit Manipulation |
|
|
| 198 |
House Robber |
Medium |
O(N) |
O(1) |
Dynamic Programming |
|
|
| 200 |
Number of Islands |
Medium |
O(R*C) |
O(R*C) |
Array, BFS, DFS, Union Find, Matrix |
|
|
| 203 |
Count Primes |
Easy |
O(N) |
O(1) |
Linked List, Recursion |
|
|
| 204 |
Count Primes |
Medium |
O(loglogN) |
O(N) |
Hash Table, Math |
|
|
| 207 |
Course Schedule |
Medium |
O(N + E) |
O(N + E) |
BFS, DFS, Graph, Topological Sort |
|
|
| 208 |
Implement Trie (Prefix Tree) |
Medium |
Varying |
Varying |
Design, Trie |
|
|
| 209 |
Minimum Size Subarray Sum |
Medium |
O(N) |
O(1) |
Array, Two Pointers, Binary Search |
|
|
| 211 |
Add and Search Word - Data structure design |
Medium |
O(M) |
O(1) |
Trie, Design |
|
|
| 213 |
House Robber II |
Medium |
O(N) |
O(1) |
Dynamic Programming |
|
|
| 215 |
Kth Largest Element in an Array |
Medium |
O(NlogK) |
O(K) |
Heap |
|
|
| 216 |
Combination Sum III |
Medium |
O(N^2) |
O(N^2) |
Array, Backtracking |
|
|
| 218 |
The Skyline Problem |
Hard |
O(NlogN) |
O(N) |
Divide and Conquer, Heap, Binary Indexed Tree, Segment Tree, Line Sweep |
|
|
| 220 |
Contains Duplicate III |
Medium |
O(N) |
O(N) |
Sort, Ordered Map |
|
|
| 221 |
Maximal Square |
Medium |
O(N * M) |
O(1) |
Array, Dynamic Programming |
|
|
| 222 |
Count Complete Tree Nodes |
Medium |
O(logN * logN) |
O(1) |
Binary Search, Tree |
|
|
| 227 |
Basic Calculator II |
Medium |
O(N) |
O(N) |
String, Stack |
|
|
| 228 |
Summary Ranges |
Easy |
O(N) |
O(1) |
Array |
|
|
| 229 |
Majority Element II |
Medium |
O(N) |
O(1) |
Array |
|
|
| 230 |
Kth Smallest Element in a BST |
Medium |
O(H + k) |
O(H + k) |
Tree, DFS |
Use general formula for tree traversal |
|
| 231 |
Power of Two |
Easy |
O(1) |
O(1) |
Bit Manipulation |
Important technique in bit manipulation |
|
| 234 |
Palindrome Linked List |
Easy |
O(N) |
O(1) |
Linked List, Two Pointers |
|
|
| 239 |
Sliding Window Maximum |
Hard |
O(N) |
O(N) |
Monotonic Dequeue, Sliding Window, Heap |
|
|
| 252 |
Meeting Rooms |
Easy |
O(NlogN) |
O(1) |
Premium, Sort |
|
🔒 |
| 253 |
Meeting Rooms II |
Medium |
O(NlogN) |
O(N) |
Premium, Heap, Greedy, Sort |
|
🔒 |
| 264 |
Ugly Number II |
Medium |
O(1) |
O(1) |
Heap, Dynamic Programming |
|
|
| 268 |
Missing Number |
Easy |
O(N) |
O(1) |
Array, Math, Bit Manipulation |
|
|
| 270 |
Closest Binary Search Tree Value |
Easy |
O(H) |
O(1) |
Premium, Binary Search, Tree |
|
🔒 |
| 273 |
Integer to English Words |
Medium |
O(logN) |
O(1) |
Math, String |
|
|
| 274 |
H-Index |
Medium |
O(NlogN) |
O(N) |
Hash Table, Sort |
There is a better solution |
|
| 279 |
Perfect Squares |
Medium |
O(NlogN) |
O(N) |
Math, Dynamic Programming, BFS |
|
|
| 283 |
Move Zeroes |
Easy |
O(N) |
O(1) |
Array, Two Pointers |
|
|
| 284 |
Peeking Iterator |
Medium |
O(NlogN) |
O(N) |
Design |
|
|
| 289 |
Game of Life |
Medium |
O(M*N) |
O(1) |
Array |
|
|
| 290 |
Word Pattern |
Easy |
O(N) |
O(N) |
Hash Table |
|
|
| 295 |
Find Median from Data Stream |
Hard |
O(logN) |
O(N) |
Design, Hard, Heap |
|
|
| 296 |
Best Meeting Point |
Hard |
O(M*N) |
O(M+N) |
Premium, Math |
|
🔒 |
| 297 |
Serialize and Deserialize Binary Tree |
Hard |
O(N) |
O(N) |
Tree, Design |
|
|
| 299 |
Bulls and Cows |
Easy |
O(N) |
O(N) |
Hash Table |
|
|
| 300 |
Longest Increasing Subsequence |
Medium |
O(NlogN) |
O(N) |
Binary Search, Dynamic Programming, Popular Algorithm |
|
|
| 304 |
Range Sum Query 2D - Immutable |
Medium |
O(1) |
O(R*C) |
Dynamic Programming |
Matrix Range Sum Trick |
|
| 307 |
Range Sum Query - Mutable |
Medium |
O(logN) |
O(logN) |
Array, Design, Binary Indexed Tree, Segment Tree |
|
|
| 310 |
Minimum Height Trees |
Medium |
O(V) |
O(V) |
BFS, Graph |
|
|
| 312 |
Burst Balloons |
Hard |
O(N^3) |
O(N^2) |
Array, Dynamic Programming |
|
|
| 315 |
Count of Smaller Numbers After Self |
Hard |
O(NlogN) |
O(N) |
Array, Binary Search, Divide and Conquer, Binary Indexed Tree, Segment Tree, Merge Sort, Ordered Set |
|
|
| 316 |
Remove Duplicate Letters |
Hard |
O(N) |
O(1) |
Greedy, Tricky, Stack |
|
|
| 317 |
Shortest Distance from All Buildings |
Hard |
O(N*M) |
O(N*M) |
BFS, Premium |
|
🔒 |
| 319 |
Bulb Switcher |
Medium |
O(1) |
O(1) |
Math, Tricky |
|
|
| 320 |
Generalized Abbreviation |
Medium |
O(N*2^N) |
O(N) |
Premium, Backtracking |
|
🔒 |
| 322 |
Coin Change |
Medium |
O(A*N) |
O(A) |
Dynamic Programming |
|
|
| 328 |
Odd Even Linked List |
Medium |
O(N) |
O(1) |
Linked List |
|
|
| 329 |
Longest Increasing Path in a Matrix |
Hard |
O(R*C) |
O(R*C) |
DFS, Topology Sort, Memoization |
|
|
| 331 |
Verify Preorder Serialization of a Binary Tree |
Medium |
O(N) |
O(N) |
String, Stack, Tree, Binary Tree |
|
|
| 334 |
Increasing Triplet Subsequence |
Medium |
O(N) |
O(1) |
Array |
|
|
| 337 |
House Robber III |
Medium |
O(N) |
O(N) |
Dynamic Programming, Tree, DFS |
|
|
| 338 |
Counting Bits |
Medium |
O(N) |
O(N) |
Dynamic Programming, Bit Manipulation |
|
|
| 342 |
Power of Four |
Easy |
O(1) |
O(1) |
Math, Bit Manipulation |
|
|
| 344 |
Integer Break |
Medium |
O(N) |
O(1) |
Math, Dynamic Programming |
|
|
| 346 |
Moving Average from Data Stream |
Easy |
O(1) |
O(N) |
Premium, Design |
|
🔒 |
| 347 |
Top K Frequent Elements |
Medium |
O(N) |
O(N) |
Hash Table, Heap |
|
|
| 348 |
Design Tic-Tac-Toe |
Medium |
O(1) |
O(N^2) |
Premium, Design |
|
🔒 |
| 351 |
Android Unlock Patterns |
Medium |
O(N!) |
O(N) |
Dynamic Programming, Backtracking, Premium |
|
🔒 |
| 354 |
Russian Doll Envelopes |
Hard |
O(NlogN) |
O(N) |
Binary Search, Dynamic Programming |
|
|
| 357 |
Count Numbers with Unique Digits |
Medium |
O(1) |
O(1) |
Math, Dynamic Programming, Backtracking |
|
|
| 361 |
Bomb Enemy |
Medium |
O(N*M) |
O(N*M) |
Premium, Dynamic Programming |
|
🔒 |
| 362 |
Design Hit Counter |
Medium |
O(1) |
O(N) |
Design, Premium |
|
🔒 |
| 363 |
Max Sum of Rectangle No Larger Than K |
Hard |
O(R*R*C*logC) |
O(R*C) |
Array, Binary Search, Dynamic Programming, Matrix, Ordered Set |
|
|
| 367 |
Valid Perfect Square |
Easy |
O(logN) |
O(1) |
Math, Binary Search |
|
|
| 376 |
Wiggle Subsequence |
Medium |
O(N) |
O(1) |
Greedy, Dynamic Programming |
|
|
| 377 |
Combination Sum IV |
Medium |
O(T*N) |
O(T) |
Dynamic Programming |
|
|
| 378 |
Kth Smallest Element in a Sorted Matrix |
Medium |
O(N^2logK) |
O(K) |
Heap, Binary Search |
|
|
| 380 |
Insert Delete GetRandom |
Medium |
O(1) |
O(N) |
Array, Hash Table, Design |
|
|
| 384 |
Shuffle an Array |
Medium |
O(N) |
O(N) |
|
|
|
| 387 |
First Unique Character in a String |
Easy |
O(N) |
O(N) |
|
|
|
| 389 |
Find the Difference |
Medium |
O(N) |
O(1) |
Hash Table, Bit Manipulation |
|
|
| 394 |
Decode String |
Medium |
O(maxK*N) |
O(N) |
Stack, DFS |
|
|
| 395 |
Longest Substring with At Least K Repeating Characters |
Medium |
O(NlogN) |
O(N) |
Divide and Conquer, Recursion, Sliding Window |
|
|
| 399 |
Evaluate Division |
Medium |
O(N*M) |
O(N) |
Union Find, Graph |
|
|
| 402 |
Remove K Digits |
Medium |
O(N) |
O(N) |
Greedy |
|
|
| 404 |
Sum of Left Leaves |
Easy |
O(N) |
O(H) |
Tree |
|
|
| 406 |
Queue Reconstruction by Height |
Medium |
O(N^2) |
O(N) |
Greedy |
Clever solution |
|
| 413 |
Arithmetic Slices |
Medium |
O(N) |
O(1) |
Math, Dynamic Programming |
|
|
| 416 |
Partition Equal Subset Sum |
Medium |
O(M*N) |
O(M) |
Dynamic Programming |
|
|
| 417 |
Pacific Atlantic Water Flow |
Medium |
O(R*C) |
O(R*C) |
DFS, BFS |
|
|
| 419 |
Battleships in a Board |
Medium |
O(N*N) |
O(1) |
Array, DFS |
|
|
| 423 |
Reconstruct Original Digits from English |
Medium |
O(N) |
O(N) |
Math |
|
|
| 425 |
Word Squares |
Hard |
Complex |
Complex |
Back Tracking, Trie, Premium |
|
🔒 |
| 428 |
Serialize and Deserialize N-ary Tree |
Hard |
O(N) |
O(H) |
Tree, Premium |
|
🔒 |
| 431 |
Encode N-ary Tree to Binary Tree |
Hard |
O(N) |
O(H) |
Tree, Premium |
|
🔒 |
| 433 |
Minimum Genetic Mutation |
Medium |
O(E+V) |
O(E+V) |
Hash Table, String, BFS |
|
|
| 435 |
Non-overlapping Intervals |
Medium |
O(NlogN) |
O(1) |
Greedy |
Tricky, Hard |
|
| 436 |
Find Right Interval |
Medium |
O(NlogN) |
O(N) |
Binary Search |
Bad Description |
|
| 437 |
Path Sum III |
Medium |
O(N) |
O(N) |
Tree |
Tricky, Hard |
|
| 438 |
Find All Anagrams in a String |
Medium |
O(N_s + N_p) |
O(1) |
Hash Table |
|
|
| 441 |
Arranging Coins |
Easy |
O(1) |
O(1) |
Math, Binary Search |
|
|
| 442 |
Find All Duplicates in an Array |
Medium |
O(N) |
O(1) |
Array |
|
|
| 445 |
Add Two Numbers II |
Medium |
O(N) |
O(N) |
Linked List |
|
|
| 449 |
Serialize and Deserialize BST |
Medium |
O(N) |
O(N) |
Tree |
|
|
| 450 |
Delete Node in a BST |
Medium |
O(H) |
O(H) |
Binary Search Tree |
|
|
| 451 |
Sort Characters By Frequency |
Medium |
O(N) |
O(N) |
Hash Table, Sorting, Pythonic |
|
|
| 452 |
Minimum Number of Arrows to Burst Balloons |
Medium |
O(NlogN) |
O(1) |
Sort, Greedy |
|
|
| 454 |
4Sum II |
Medium |
O(N^2) |
O(N^2) |
Array |
|
|
| 456 |
132 Pattern |
Medium |
O(N) |
O(N) |
Stack |
|
|
| 458 |
Poor Pigs |
Hard |
O(1) |
O(1) |
Math |
|
|
| 462 |
Minimum Moves to Equal Array Elements II |
Median |
O(NlogN) |
O(N) |
Math |
|
|
| 463 |
Island Perimeter |
Easy |
O(N*M) |
O(1) |
Greedy |
|
|
| 470 |
Implement Rand10() Using Rand7() |
Medium |
O(1) |
O(1) |
Math |
|
|
| 473 |
Matchsticks to Square |
Medium |
O(4^N) |
O(4^N) |
DFS, Dynamic Programming |
|
|
| 474 |
Ones and Zeroes |
Medium |
O(K*M*N) |
O(K*M*N) |
Dynamic Programming |
|
|
| 476 |
Number Complement |
Easy |
O(N) |
O(1) |
Bit Manipulation |
|
|
| 478 |
Generate Random Point in a Circle |
Medium |
O(1) |
O(1) |
Math, Random, Rejection Sampling |
|
|
| 491 |
Increasing Subsequences |
Medium |
O(Combination) |
O(Combination) |
DFS |
|
|
| 494 |
Target Sum |
Medium |
O(N*T) |
O(T) |
Dynamic Programming, DFS |
Template for DP |
|
| 495 |
Teemo Attacking |
Medium |
O(N) |
O(1) |
Array |
|
|
| 497 |
Random Point in Non-overlapping Rectangles |
Medium |
O(logN) |
O(N) |
Design, Binary Search |
|
|
| 498 |
Diagonal Traverse |
Medium |
O(R*C) |
O(R*C) |
Array |
|
|
| 502 |
IPO |
Hard |
O(NlogN) |
O(N) |
Array, Greedy, Sorting, Heap |
|
|
| 506 |
Relative Ranks |
Medium |
O(NlogN) |
O(N) |
Array, Sorting, Heap (Priority Queue) |
|
|
| 510 |
Inorder Successor in BST II |
Medium |
O(H) |
O(1) |
Tree, Premium |
|
🔒 |
| 514 |
Freedom Trail |
Hard |
O(N*M) |
O(N*M) |
String, Dynamic Programming, Depth-First Search, Breadth-First Search |
|
🔒 |
| 520 |
Detect Capital |
Easy |
O(N) |
O(1) |
|
|
|
| 524 |
Longest Word in Dictionary through Deleting |
Medium |
Complex |
Complex |
Two Pointers, Sort |
|
|
| 525 |
Contiguous Array |
Medium |
O(N) |
O(N) |
Hash Table |
Very good problem |
|
| 528 |
Random Pick with Weight |
Medium |
O(N), O(logN) |
O(N), O(1) |
Binary Search, Random |
Pythonic |
|
| 532 |
K-diff Pairs in an Array |
Medium |
O(N) |
O(N) |
Array, Two Pointers |
|
|
| 538 |
Convert BST to Greater Tree |
Medium |
O(N) |
O(H) |
Tree, BFS, DFS, Recursion |
|
|
| 540 |
Single Element in a Sorted Array |
Medium |
O(logN) |
O(1) |
Binary Search |
|
|
| 542 |
01 Matrix |
Medium |
O(R*C) |
O(R*C) |
BFS, DFS |
|
|
| 554 |
Brick Wall |
Medium |
O(N) |
O(N) |
Hash Table |
|
|
| 563 |
Binary Tree Tilt |
Easy |
O(N) |
O(H) |
Tree, DFS, Recursion |
|
|
| 567 |
Permutation in String |
Medium |
O(S1 + S2) |
O(1) |
String, Two Pointers, Sliding Window |
|
|
| 573 |
Squirrel Simulation |
Medium |
O(N) |
O(1) |
Premium, Math |
|
🔒 |
| 576 |
Out of Boundary Paths |
Medium |
O(N*m*n) |
O(N*m*n) |
Dynamic Programming |
|
|
| 581 |
Shortest Unsorted Continuous Subarray |
Medium |
O(N) |
O(1) |
Array |
|
|
| 583 |
Delete Operation for Two Strings |
Medium |
O(N^2) |
O(N) |
Dynamic Programming, String |
|
|
| 589 |
N-ary Tree Preorder Traversal |
Easy |
O(N) |
O(N) |
Tree |
|
|
| 593 |
Valid Square |
Medium |
O(1) |
O(1) |
Math |
|
|
| 605 |
Can Place Flowers |
Easy |
O(N) |
O(1) |
Array, Greedy |
|
|
| 611 |
Valid Triangle Number |
Medium |
O(N^2) |
O(1) |
Array, Two Pointers, Binary Search, Greedy, Sorting |
|
|
| 621 |
Task Scheduler |
Medium |
O(N) |
O(1) |
Array, Hash Table, Greedy, Sorting, Heap (Priority Queue), Counting |
Greedy |
|
| 622 |
Design Circular Queue |
Medium |
O(1) |
O(1) |
Design, Queue |
|
|
| 623 |
Add One Row to Tree |
Medium |
O(N) |
O(N) |
Tree |
|
|
| 624 |
Maximum Distance in Arrays |
Easy |
O(N) |
O(1) |
Hash Table, Array, Premium |
|
🔒 |
| 629 |
K Inverse Pairs Array |
Hard |
O(N * K) |
O(K) |
Dynamic Programming |
|
|
| 633 |
Sum of Square Numbers |
Medium |
O(logN) |
O(logN) |
Math, Two Pointers, Binary Search |
|
|
| 636 |
Exclusive Time of Functions |
Medium |
O(N) |
O(N) |
Array, Stack |
|
|
| 639 |
Decode Ways II |
Hard |
O(N) |
O(N) |
String, Dynamic Programming |
|
|
| 646 |
Maximum Length of Pair Chain |
Medium |
O(NlogN) |
O(N) |
Greedy, Dynamic Programming |
|
|
| 655 |
Print Binary Tree |
Medium |
O(N) |
O(H) |
Tree |
|
|
| 658 |
Find K Closest Elements |
Medium |
O(logN+K) |
O(K) |
Tree |
|
|
| 659 |
Split Array into Consecutive Subsequences |
Medium |
O(N) |
O(1) |
Greedy |
|
|
| 662 |
Maximum Width of Binary Tree |
Medium |
O(N) |
O(N) |
Tree |
|
|
| 665 |
Non-decreasing Array |
Medium |
O(N) |
O(1) |
Array |
|
|
| 667 |
Beautiful Arrangement II |
Medium |
O(N) |
O(N) |
Array |
|
|
| 669 |
Trim a Binary Search Tree |
Medium |
O(N) |
O(N) |
Tree, Recursion |
|
|
| 670 |
Maximum Swap |
Medium |
O(N) |
O(N) |
Array, Math |
|
|
| 673 |
Number of Longest Increasing Subsequence |
Medium |
O(N^2) |
O(N) |
Dynamic Programming |
|
|
| 677 |
Map Sum Pairs |
Medium |
O(K) |
O(K) |
Trie |
|
|
| 684 |
Redundant Connection |
Medium |
O(NlogN) |
O(N) |
DFS, BFS, Union Find, Graph |
|
|
| 696 |
Count Binary Substrings |
Medium |
O(N) |
O(1) |
String |
|
|
| 697 |
Degree of an Array |
Easy |
O(N) |
O(N) |
Array, Hash Table |
|
|
| 700 |
Search in a Binary Search Tree |
Easy |
O(H) |
O(1) |
Tree |
|
|
| 701 |
Insert into a Binary Search Tree |
Medium |
O(H) |
O(1) |
Tree |
|
|
| 702 |
Search in a Sorted Array of Unknown Size |
Medium |
O(logN) |
O(1) |
Binary Search, Premium |
|
🔒 |
| 705 |
Design HashSet |
Easy |
Varying |
Varying |
Design HashSet |
|
|
| 708 |
Insert into a Sorted Circular Linked List |
Medium |
O(N) |
O(1) |
Linked List, Premium |
|
🔒 |
| 713 |
Subarray Product Less Than K |
Medium |
O(N) |
O(1) |
Array, Two Pointers |
|
|
| 714 |
Best Time to Buy and Sell Stock with Transaction Fee |
Medium |
O(N) |
O(1) |
Array, Dynamic Programming, Greedy |
|
|
| 717 |
1-bit and 2-bit Characters |
Easy |
O(N) |
O(1) |
Array, Greedy |
|
|
| 721 |
Accounts Merge |
Medium |
Complex |
Complex |
Union-Find, DFS |
Template for Union-Find |
|
| 724 |
Find Pivot Index |
Easy |
O(N) |
O(1) |
Array, Prefix Sum |
|
|
| 725 |
Split Linked List in Parts |
Medium |
O(N) |
O(N) |
Linked List |
|
|
| 729 |
My Calendar I |
Medium |
O(NlogN) |
O(N) |
Tree |
|
|
| 733 |
Flood Fill |
Easy |
O(N) |
O(N) |
DFS |
|
|
| 734 |
Sentence Similarity |
Easy |
O(N) |
O(N) |
Premium, Hash Table |
|
🔒 |
| 735 |
Asteroid Collision |
Medium |
O(N) |
O(N) |
Stack |
|
|
| 737 |
Sentence Similarity II |
Medium |
O(NlogP + P) or O(NP) |
O(N) |
Premium, DFS, Union Find |
|
🔒 |
| 738 |
Monotone Increasing Digits |
Medium |
O(logN) |
O(logN) |
Greedy |
|
|
| 739 |
Daily Temperatures |
Medium |
O(N) |
O(N) |
Hash Table, Stack |
|
|
| 740 |
Delete and Earn |
Medium |
O(N+M) |
O(N+M) |
Dynamic Programming |
|
|
| 743 |
Network Delay Time |
Medium |
O(ElogE) |
O(N + E) |
Heap, BFS, DFS, Graph |
|
|
| 746 |
Min Cost Climbing Stairs |
Easy |
O(N) |
O(1) |
Array, DP |
|
|
| 752 |
Open the Lock |
Medium |
O(N^2*D^N) |
O(N^2*D^N) |
BFS |
|
|
| 754 |
Reach a Number |
Medium |
O(logN) |
O(1) |
Math |
|
|
| 763 |
Partition Labels |
Medium |
O(N) |
O(N) |
Greedy, Two Pointers |
|
|
| 764 |
Largest Plus Sign |
Medium |
O(N^2) |
O(N^2) |
Array, Dynamic Programming |
|
|
| 767 |
Reorganize String |
Medium |
O(NlogN) |
O(N) |
String, Heap, Greedy, Sort |
|
|
| 768 |
Max Chunks To Make Sorted II |
Hard |
O(N) |
O(N) |
Array |
|
|
| 769 |
Max Chunks To Make Sorted |
Medium |
O(N) |
O(1) |
Array |
|
|
| 775 |
Global and Local Inversions |
Medium |
O(N) |
O(1) |
Array, Math |
|
|
| 778 |
Swim in Rising Water |
Medium |
O(R*C*logN) |
O(R*C) |
Binary Search, Heap, DFS, Union Find |
|
|
| 784 |
Letter Case Permutation |
Medium |
O(2^N) |
O(2^N) |
Backtracking, Bit Manipulation |
|
|
| 785 |
Is Graph Bipartite? |
Medium |
O(E+V) |
O(E+V) |
BFS, DFS, Graph |
|
|
| 786 |
K-th Smallest Prime Fraction |
Medium |
O(KlogK) |
O(K) |
Array, Two Pointers, Binary Search, Sorting, Heap (Priority Queue) |
|
|
| 787 |
Cheapest Flights Within K Stops |
Medium |
Complex |
Complex |
Dijkstra's Algorithm, Graph |
Quite hard |
|
| 789 |
Escape The Ghosts |
Medium |
O(N) |
O(1) |
Math |
|
|
| 791 |
Custom Sort String |
Medium |
O(N) |
O(N) |
String |
|
|
| 792 |
Number of Matching Subsequences |
Medium |
O(N + M * L) |
O(M) |
Array |
|
|
| 794 |
Valid Tic-Tac-Toe State |
Medium |
O(1) |
O(1) |
Array, String |
|
|
| 795 |
Number of Subarrays with Bounded Maximum |
Medium |
O(N) |
O(1) |
Array |
|
|
| 797 |
All Paths From Source to Target |
Medium |
O(2^N * N) |
O(2^N * N) |
Backtracking, DFS |
|
|
| 799 |
Champagne Tower |
Medium |
O(R^2) |
O(R^2) |
Dynamic Programming |
|
|
| 802 |
Find Eventual Safe States |
Medium |
O(V+E) |
O(V+E) |
DFS, Graph |
|
|
| 820 |
Short Encoding of Words |
Medium |
O(N*M) |
O(N*M) |
Trie |
|
|
| 823 |
Binary Trees With Factors |
Medium |
O(N*N) |
O(N) |
Dynamic Programming |
|
|
| 825 |
Friends Of Appropriate Ages |
Medium |
O(N) |
O(1) |
Array |
|
|
| 827 |
Making A Large Island |
Hard |
O(N^2) |
O(N^2) |
Array, DFS, BFS, Union-Find, Matrix |
|
|
| 830 |
Positions of Large Groups |
Easy |
O(N) |
O(1) |
|
|
|
| 833 |
Find And Replace in String |
Medium |
O(N) |
O(N) |
Dynamic Programming |
|
|
| 834 |
Sum of Distances in Tree |
Hard |
O(N) |
O(N) |
Dynamic Programming, Tree, DFS, Graph |
|
|
| 835 |
Image Overlap |
Medium |
O(N^2) |
O(N) |
|
|
|
| 838 |
Push Dominoes |
Medium |
O(N) |
O(N) |
|
|
|
| 841 |
Keys and Rooms |
Medium |
O(N^2) |
O(N) |
DFS, Graph |
|
|
| 845 |
Longest Mountain in Array |
Medium |
O(N) |
O(1) |
Two Pointers |
|
|
| 846 |
Hand of Straights |
Medium |
O(MlogM+NW) |
O(N) |
Ordered Map |
|
|
| 847 |
Shortest Path Visiting All Nodes |
Hard |
O(2^N * N^2) |
O(2^N * N) |
Dynamic Programming, Bit Manipulation, BFS, Graph Bitmask |
|
|
| 848 |
Shifting Letters |
Medium |
O(N) |
O(N) |
Array, String |
|
|
| 849 |
Maximize Distance to Closest Person |
Medium |
O(N) |
O(1) |
Array |
|
|
| 851 |
Loud and Rich |
Medium |
O(N^2) |
O(N^2) |
DFS |
|
|
| 853 |
Car Fleet |
Medium |
O(NlogN) |
O(N) |
Sort |
|
|
| 857 |
Minimum Cost to Hire K Workers |
Medium |
O(NlogN) |
O(K) |
Array, Greedy, Sorting, Heap (Priority Queue) |
|
|
| 858 |
Mirror Reflection |
Medium |
O(logN) |
O(1) |
Math |
|
|
| 859 |
Buddy Strings |
Easy |
O(N) |
O(1) |
String |
|
|
| 861 |
Score After Flipping Matrix |
Medium |
O(R*C) |
O(R*C) |
Array, Greedy, Bit Manipulation, Matrix |
|
|
| 863 |
All Nodes Distance K in Binary Tree |
Medium |
O(N) |
O(N) |
Tree, BFS, DFS |
|
|
| 865 |
Smallest Subtree with all the Deepest Nodes |
Medium |
O(N) |
O(N) |
Tree, BFS, DFS, Recursion |
|
|
| 869 |
Reordered Power of 2 |
Medium |
O(logN) |
O(1) |
Math |
|
|
| 870 |
Advantage Shuffle |
Medium |
O(NlogN) |
O(N) |
Array, Greedy |
|
|
| 872 |
Leaf-Similar Trees |
Easy |
O(N) |
O(N) |
Tree, DFS, Binary Tree |
Iterator |
|
| 873 |
Length of Longest Fibonacci Subsequence |
Medium |
O(N^2) |
O(N^2) |
Array, Dynamic Programming |
|
|
| 875 |
Koko Eating Bananas |
Medium |
O(NlogM) |
O(1) |
Binary Search |
|
|
| 880 |
Decoded String at Index |
Medium |
O(N) |
O(1) |
Stack |
Good problem |
|
| 881 |
Boats to Save People |
Medium |
O(NlogN) |
O(N) |
Two Pointers, Greedy |
|
|
| 886 |
Possible Bipartition |
Medium |
O(N + E) |
O(N + E) |
DFS |
Good problem |
|
| 890 |
Find and Replace Pattern |
Medium |
O(N*K) |
O(N*K) |
String |
|
|
| 892 |
Surface Area of 3D Shapes |
Easy |
O(N*N) |
O(1) |
Math, Geometry |
|
|
| 895 |
Maximum Frequency Stack |
Medium |
O(1) |
O(N) |
Hash Table, Stack |
|
|
| 901 |
Online Stock Span |
Medium |
O(1) |
O(N) |
Monotonic Stack |
|
|
| 902 |
Numbers At Most N Given Digit Set |
Hard |
O(LogN) |
O(1) |
Math, Dynamic Programming |
|
|
| 904 |
Fruit Into Baskets |
Medium |
O(N) |
O(1) |
Two Pointers |
|
|
| 905 |
Sort Array By Parity |
Easy |
O(N) |
O(1) |
Array |
|
|
| 906 |
Super Palindromes |
Hard |
Complex |
Complex |
Math |
|
|
| 910 |
Smallest Range II |
Medium |
O(NlogN) |
O(N) |
Math, Greedy |
|
|
| 911 |
Online Election |
Medium |
O(N + QlogN) |
O(N) |
Binary Search |
|
|
| 915 |
Partition Array into Disjoint Intervals |
Medium |
O(N) |
O(N) |
Array |
|
|
| 916 |
Word Subsets |
Medium |
O(A_t + B_t) |
O(L) |
String |
|
|
| 918 |
Maximum Sum Circular Subarray |
Medium |
O(N) |
O(1) |
Array, Dynamic Programming |
|
|
| 919 |
Complete Binary Tree Inserter |
Medium |
O(N) |
O(1) |
Tree |
|
|
| 923 |
3Sum With Multiplicity |
Medium |
O(N^2) |
O(N) |
Two Pointers |
|
|
| 926 |
Flip String to Monotone Increasing |
Medium |
O(N) |
O(N) |
Array |
|
|
| 930 |
Binary Subarrays With Sum |
Medium |
O(N) |
O(N) |
Hash Table, Two Pointers |
|
|
| 931 |
Minimum Falling Path Sum |
Medium |
O(R*C) |
O(C) |
Array, Dynamic Programming, Matrix |
|
|
| 933 |
Number of Recent Calls |
Easy |
O(1) |
O(1) |
Queue |
|
|
| 934 |
Shortest Bridge |
Medium |
O(E+V) |
O(E+V) |
BFS, DFS |
|
|
| 935 |
Knight Dialer |
Medium |
O(N) |
O(1) |
Dynamic Programming |
|
|
| 941 |
Valid Mountain Array |
Easy |
O(N) |
O(1) |
Array |
|
|
| 946 |
Validate Stack Sequences |
Medium |
O(N) |
O(N) |
Stack |
|
|
| 948 |
Bag of Tokens |
Medium |
O(NlogN) |
O(N) |
Greedy |
|
|
| 953 |
Verifying an Alien Dictionary |
Easy |
O(A) |
O(1) |
Hash Table |
|
|
| 954 |
Array of Doubled Pairs |
Medium |
O(NlogN) |
O(N) |
Array, Hash Table, Greedy, Sorting |
|
|
| 957 |
Prison Cells After N Days |
Medium |
O(1) |
O(1) |
Hash Table |
|
|
| 958 |
Check Completeness of a Binary Tree |
Medium |
O(N) |
O(N) |
Tree |
|
|
| 962 |
Maximum Width Ramp |
Medium |
O(NlogN) |
O(N) |
Array |
|
|
| 966 |
Vowel Spellchecker |
Medium |
O(N) |
O(N) |
Hash Table, String |
|
|
| 967 |
Numbers With Same Consecutive Differences |
Medium |
O(N*2^N) |
O(2^N) |
DFS |
|
|
| 968 |
Binary Tree Cameras |
Hard |
O(N) |
O(H) |
Greedy, Tree, Dynamic Programming, DFS |
New Technique |
|
| 969 |
Pancake Sorting |
Medium |
O(N^2) |
O(N) |
Array |
|
|
| 970 |
Powerful Integers |
Medium |
O(logx*logy) |
O(logx+logy) |
Hash Table, Math |
|
|
| 971 |
Flip Binary Tree To Match Preorder Traversal |
Medium |
O(N) |
O(N) |
Tree, DFS |
|
|
| 973 |
K Closest Points to Origin |
Medium |
O(N log(K)) |
O(K) |
Divide and Conquer, Heap, Sort |
|
|
| 974 |
Subarray Sums Divisible by K |
Medium |
O(N) |
O(K) |
Array, Hash Table |
|
|
| 976 |
Largest Perimeter Triangle |
Medium |
O(NlogN) |
O(N) |
Math, Sort |
|
|
| 977 |
Squares of a Sorted Array |
Easy |
O(N) |
O(N) |
Array, Two Pointers |
|
|
| 979 |
Distribute Coins in Binary Tree |
Medium |
O(N) |
O(H) |
Tree, DFS |
|
|
| 980 |
Unique Paths III |
Medium |
O(2^N) |
O(N) |
Backtracking, DFS |
|
|
| 983 |
Minimum Cost For Tickets |
Medium |
O(365) |
O(365) |
LRU Cache, Dynamic Programming |
|
|
| 986 |
Interval List Intersections |
Medium |
O(N + M) |
O(1) |
Two Pointers |
|
|
| 987 |
Vertical Order Traversal of a Binary Tree |
Medium |
O(NlogN) |
O(N) |
Hash Table, Tree |
|
|
| 991 |
Broken Calculator |
Medium |
O(logN) |
O(1) |
Math, Greedy |
|
|
| 992 |
Subarrays with K Different Integers |
Hard |
O(N) |
O(N) |
Hash Talble, Two Pointers, Sliding Window |
|
|
| 993 |
Cousins in Binary Tree |
Easy |
O(N) |
O(H) |
Trees, Recursion |
|
|
| 994 |
Rotting Oranges |
Medium |
O(N^2) |
O(N) |
Trees, Recursion |
|
|
| 997 |
Find the Town Judge |
Medium |
O(N) |
O(N) |
Array, Hash Table, Graph |
|
|
| 1003 |
Check If Word Is Valid After Substitutions |
Medium |
O(N) |
O(N) |
String, Stack |
|
|
| 1004 |
Max Consecutive Ones III |
Medium |
O(N) |
O(1) |
Sliding Window, Two Pointers |
|
|
| 1007 |
Minimum Domino Rotations For Equal Row |
Medium |
O(N) |
O(1) |
Array, Greedy |
|
|
| 1009 |
Complement of Base 10 Integer |
Easy |
O(logN) |
O(1) |
Bit Manipulation |
|
|
| 1010 |
Pairs of Songs With Total Durations Divisible by 60 |
Medium |
O(N) |
O(1) |
Array, Math |
|
|
| 1011 |
Capacity To Ship Packages Within D Days |
Medium |
O(NlogN) |
O(1) |
Array, Binary Search |
|
|
| 1014 |
Best Sightseeing Pair |
Medium |
O(N) |
O(1) |
Array |
|
|
| 1015 |
Smallest Integer Divisible by K |
Medium |
O(K) |
O(K) |
Math |
|
|
| 1022 |
Sum of Root To Leaf Binary Numbers |
Easy |
O(N) |
O(H) |
Tree |
|
|
| 1023 |
Camelcase Matching |
Medium |
O(Q*N) |
O(Q) |
String, Trie |
|
|
| 1024 |
Video Stitching |
Medium |
O(NlogN) |
O(1) |
Dynamic Programming |
|
|
| 1026 |
Maximum Difference Between Node and Ancestor |
Medium |
O(N) |
O(H) |
Tree, DFS |
|
|
| 1029 |
Two City Scheduling |
Easy |
O(NlogN) |
O(N) |
Greedy |
Good Problem |
|
| 1032 |
Stream of Characters |
Hard |
O(M) |
O(M) |
Trie |
|
|
| 1035 |
Uncrossed Lines |
Medium |
O(N^2) |
O(N) |
Array, Dynamic Programming |
|
|
| 1042 |
Flower Planting With No Adjacent |
Medium |
O(V+E) |
O(V+E) |
Graph |
|
|
| 1048 |
Longest String Chain |
Medium |
O(N*logN+N*C*C) |
O(N) |
Hash Table, Dynamic Programming |
|
|
| 1049 |
Last Stone Weight II |
Medium |
O(N*S) |
O(N*S) |
Hash Table, Dynamic Programming |
Template for DP |
|
| 1052 |
Grumpy Bookstore Owner |
Medium |
O(N) |
O(N) |
Sliding Window, Array |
|
|
| 1053 |
Previous Permutation With One Swap |
Medium |
O(N) |
O(N) |
Array, Greedy |
|
|
| 1054 |
Distant Barcodes |
Medium |
O(NlogN) |
O(N) |
Sort, Heap |
|
|
| 1060 |
Missing Element in Sorted Array |
Medium |
O(logN) |
O(1) |
Binary Search, Premium |
|
🔒 |
| 1061 |
Lexicographically Smallest Equivalent String |
Medium |
O(N) |
O(N) |
DFS, Union Find, Premium |
|
🔒 |
| 1074 |
Number of Submatrices That Sum to Target |
Hard |
O(R*R*C) |
O(R*C) |
Array, Dynamic Programming, Sliding Window |
|
|
| 1080 |
Insufficient Nodes in Root to Leaf Paths |
Medium |
O(N) |
O(N) |
DFS |
|
|
| 1091 |
Shortest Path in Binary Matrix |
Medium |
O(N) |
O(N) |
BFS |
|
|
| 1094 |
Car Pooling |
Medium |
O(N) |
O(1) |
Car Pooling |
|
|
| 1109 |
Corporate Flight Bookings |
Medium |
O(N) |
O(N) |
Array, Math |
|
|
| 1115 |
Print FooBar Alternately |
Medium |
N/A |
N/A |
Concurrency |
|
|
| 1116 |
Print Zero Even Odd |
Medium |
N/A |
N/A |
Concurrency |
|
|
| 1130 |
Minimum Cost Tree From Leaf Values |
Medium |
O(N) |
O(N) |
Dynamic Programming, Tree, Stack |
|
|
| 1143 |
Longest Common Subsequence |
Medium |
O(M * N) |
O(M + N) |
String, Dynamic Programming |
|
|
| 1155 |
Number of Dice Rolls With Target Sum |
Medium |
O(Complex) |
O(Complex) |
Graph, BFS |
|
|
| 1162 |
As Far from Land as Possible |
Medium |
O(N*M) |
O(N*M) |
Graph, BFS |
|
|
| 1171 |
Remove Zero Sum Consecutive Nodes from Linked List |
Medium |
O(N) |
O(N) |
Hash Table, Linked List |
|
|
| 1178 |
Number of Valid Words for Each Puzzle |
Medium |
O(Complex) |
O(Complex) |
Array, Hash Table, String, Bit Manipulation, Trie |
|
|
| 1192 |
Critical Connections in a Network |
Medium |
O(V+E) |
O(V+E) |
DFS, Tarjan |
New Algorithm |
|
| 1208 |
Get Equal Substrings Within Budget |
Medium |
O(N) |
O(N) |
String, Binary Search, Sliding Window, Prefix Sum |
|
|
| 1209 |
Remove All Adjacent Duplicates in String II |
Medium |
O(N) |
O(N) |
Stack |
|
|
| 1217 |
Minimum Cost to Move Chips to The Same Position |
Easy |
O(N) |
O(1) |
Math, Greedy, Array |
|
|
| 1218 |
Longest Arithmetic Subsequence of Given Difference |
Medium |
O(N) |
O(N) |
Hash Table, Math, Dynamic Programming |
|
|
| 1219 |
Minimum CostPath with Maximum Gold |
Medium |
O(R*C+N*2^N) |
O(N) |
Backtracking |
|
|
| 1220 |
Count Vowels Permutation |
Hard |
O(N) |
O(N) |
Dynamic Programming |
|
|
| 1232 |
Check If It Is a Straight Line |
Easy |
O(N) |
O(1) |
Math, Pythonic, Geometry |
|
|
| 1239 |
Maximum Length of a Concatenated String with Unique Characters |
Medium |
O(2^N) |
O(N) |
Backtracking, Bit Manipulation |
|
|
| 1249 |
Minimum Remove to Make Valid Parentheses |
Medium |
O(N) |
O(N) |
Stack, String |
|
|
| 1277 |
Count Square Submatrices with All Ones |
Medium |
O(N * M) |
O(1) |
Array, Dynamic Programming |
|
|
| 1283 |
Find the Smallest Divisor Given a Threshold |
Medium |
O(NlogM) |
O(1) |
Binary Search |
|
|
| 1288 |
Remove Covered Intervals |
Medium |
O(N) |
O(1) |
Greedy, Sort, Line Sweep |
|
|
| 1289 |
Minimum Falling Path Sum II |
Hard |
O(N*M*M) |
O(1) |
Array, Dynamic Programming, Matrix |
|
|
| 1290 |
Convert Binary Number in a Linked List to Integer |
Easy |
O(N) |
O(1) |
Linked List, Bit Manipulation |
|
|
| 1291 |
Sequential Digits |
Medium |
O(N) |
O(N) |
Backtracking |
|
|
| 1293 |
Shortest Path in a Grid with Obstacles Elimination |
Hard |
O(R*C) |
O(R*C) |
Array, BFS, Matrix |
|
|
| 1298 |
Maximum Candies You Can Get from Boxes |
Medium |
O(B+K) |
O(B) |
BFS |
|
|
| 1305 |
All Elements in Two Binary Search Trees |
Medium |
O(N) |
O(N) |
Sort, Tree |
|
|
| 1306 |
All Elements inJump Game III |
Medium |
O(N) |
O(N) |
BFS, DFS, Recursion |
|
|
| 1315 |
Sum of Nodes with Even-Valued Grandparent |
Medium |
O(N) |
O(N) |
Tree, DFS |
|
|
| 1325 |
Delete Leaves With a Given Value |
Medium |
O(N) |
O(N) |
Tree, Depth-First Search, Binary Tree |
|
|
| 1332 |
Remove Palindromic Subsequences |
Easy |
O(N) |
O(1) |
String |
|
|
| 1337 |
The K Weakest Rows in a Matrix |
Easy |
O(MlogKlogN) |
O(K) |
Heap, Array, Binary Search |
|
|
| 1339 |
Maximum Product of Splitted Binary Tree |
Medium |
O(N) |
O(N) |
Tree, DFS, Binary Tree |
|
|
| 1344 |
Angle Between Hands of a Clock |
Medium |
O(1) |
O(1) |
Math |
|
|
| 1345 |
Jump Game IV |
Hard |
O(N) |
O(N) |
BFS |
|
|
| 1354 |
Construct Target Array With Multiple Sums |
Hard |
O(NlogN) |
O(N) |
Greedy, Heap |
Very Hard |
|
| 1371 |
Find the Longest Substring Containing Vowels in Even Counts |
Medium |
O(N) |
O(N) |
String |
|
|
| 1375 |
Bulb Switcher III |
Medium |
O(N) |
O(1) |
Array |
|
|
| 1387 |
Sort Integers by The Power Value |
Medium |
O(NlogK) |
O(N) |
Sort, Graph |
|
|
| 1395 |
Count Number of Teams |
Medium |
O(N^2) |
O(1) |
Array |
|
|
| 1396 |
Design Underground System |
Medium |
O(N) |
O(N) |
Design |
|
|
| 1405 |
Longest Happy String |
Medium |
O(N) |
O(N) |
Greedy, Dynamic Programming |
|
|
| 1419 |
Minimum Number of Frogs Croaking |
Medium |
O(N) |
O(1) |
String |
|
|
| 1423 |
Maximum Points You Can Obtain from Cards |
Medium |
O(N) |
O(1) |
Array, Dynamic Programming, Sliding Window |
|
|
| 1424 |
Diagonal Traverse II |
Medium |
O(A) |
O(A) |
Array |
|
|
| 1426 |
Counting Elements |
Easy |
O(N) |
O(N) |
Array, Premium |
|
🔒 |
| 1427 |
Perform String Shifts |
Easy |
O(N + S) |
O(1) |
Premium |
|
🔒 |
| 1437 |
Check If All 1's Are at Least Length K Places Away |
Easy |
O(N) |
O(1) |
Array |
|
|
| 1438 |
Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit |
Medium |
O(N) |
O(N) |
Array, Queue, Sliding Window, Heap, Ordered Set, Monotonic Queue |
|
|
| 1441 |
Build an Array With Stack Operations |
Easy |
O(N) |
O(N) |
Pythonic |
|
|
| 1442 |
Count Triplets That Can Form Two Arrays of Equal XOR |
Medium |
O(N) |
O(N) |
Array, Math, Bit Manipulation |
|
|
| 1443 |
Minimum Time to Collect All Apples in a Tree |
Medium |
O(E) |
O(E) |
Tree, DFS |
|
|
| 1444 |
Number of Ways of Cutting a Pizza |
Hard |
O(K*R*C*(R+C)) |
O(K*R*C) |
Dynamic Programming |
|
|
| 1446 |
Consecutive Characters |
Easy |
O(N) |
O(1) |
String |
|
|
| 1447 |
Simplified Fractions |
Medium |
Varying |
Varying |
|
|
|
| 1448 |
Count Good Nodes in Binary Tree |
Medium |
O(N) |
O(H) |
Tree, DFS |
|
|
| 1450 |
Number of Students Doing Homework at a Given Time |
Easy |
O(N) |
O(1) |
|
|
|
| 1451 |
Rearrange Words in a Sentence |
Medium |
O(N * logN) |
O(1) |
String, Sort |
|
|
| 1452 |
People Whose List of Favorite Companies Is Not a Subset of Another List |
Medium |
O(N^2) |
O(N) |
String, Sort |
There is a better solution |
|
| 1455 |
Check If a Word Occurs As a Prefix of Any Word in a Sentence |
Medium |
O(N) |
O(1) |
String, Pythonic |
|
|
| 1456 |
Maximum Number of Vowels in a Substring of Given Length |
Medium |
O(N) |
O(1) |
String, Sliding Window |
|
|
| 1457 |
Pseudo-Palindromic Paths in a Binary Tree |
Medium |
O(N) |
O(H) |
Bit Manipulation, Tree, DFS |
|
|
| 1460 |
Make Two Arrays Equal by Reversing Sub-arrays |
Easy |
O(N) |
O(1) |
Array |
|
|
| 1461 |
Check If a String Contains All Binary Codes of Size K |
Medium |
O(N) |
O(2**K) |
String, Bit Manipulation |
|
|
| 1463 |
Cherry Pickup II |
Hard |
O(R*C*C) |
O(R*C*C) |
Array, Dynamic Programming, Matrix |
|
|
| 1464 |
Maximum Product of Two Elements in an Array |
Easy |
O(N) |
O(1) |
Array |
|
|
| 1465 |
Maximum Area of a Piece of Cake After Horizontal and Vertical Cuts |
Medium |
O(NlogN) |
O(N) |
Array |
|
|
| 1466 |
Reorder Routes to Make All Paths Lead to the City Zero |
Medium |
O(|V|) |
O(|V|) |
Tree, DFS |
|
|
| 1470 |
Shuffle the Array |
Easy |
O(N) |
O(N) |
Array |
There is a better solution |
|
| 1471 |
The k Strongest Values in an Array |
Medium |
O(NlogN) |
O(N) |
Array, Sort |
There is a better solution |
|
| 1472 |
Design Browser History |
Medium |
O(1) |
O(1) |
Design |
|
|
| 1474 |
Delete N Nodes After M Nodes of a Linked List |
Easy |
O(N) |
O(1) |
Linked List, Premium |
|
🔒 |
| 1475 |
Final Prices With a Special Discount in a Shop |
Easy |
O(N) |
O(1) |
Monotonic Stack |
|
|
| 1476 |
Subrectangle Queries |
Easy |
Varying |
Varying |
Design |
|
|
| 1480 |
Running Sum of 1d Array |
Easy |
O(N) |
O(1) |
|
|
|
| 1481 |
Least Number of Unique Integers after K Removals |
Medium |
O(NlogN) |
O(N) |
Array, Sort |
|
|
| 1482 |
Minimum Number of Days to Make m Bouquets |
Medium |
O(NlogN) |
O(N) |
Array, Binary Search |
|
|
| 1486 |
XOR Operation in an Array |
Easy |
O(1) |
O(1) |
Bit Manipulation |
|
|
| 1491 |
Average Salary Excluding the Minimum and Maximum Salary |
Easy |
O(N) |
O(1) |
|
|
|
| 1492 |
The kth Factor of n |
Medium |
O(logN) |
O(logN) |
Math, Tricky |
|
|
| 1493 |
Longest Subarray of 1's After Deleting One Element |
Medium |
O(N) |
O(1) |
Array |
|
|
| 1496 |
Path Crossing |
Easy |
O(N) |
O(N) |
String |
|
|
| 1502 |
Can Make Arithmetic Progression From Sequence |
Easy |
O(NlogN) |
O(1) |
Array |
|
|
| 1507 |
Reformat Date |
Easy |
O(1) |
O(1) |
String |
|
|
| 1508 |
Range Sum of Sorted Subarray Sums |
Medium |
O(N^2logN) |
O(N^2) |
|
|
|
| 1509 |
Minimum Difference Between Largest and Smallest Value in Three Moves |
Medium |
O(NlogN) |
O(1) |
|
|
|
| 1510 |
Stone Game IV |
Hard |
O(N*N^0.5) |
O(N) |
Dynamic Programming |
|
|
| 1512 |
Number of Good Pairs |
Easy |
O(N) |
O(N) |
|
|
|
| 1513 |
Number of Substrings With Only 1s |
Medium |
O(N) |
O(N) |
String, Math |
|
|
| 1518 |
Water Bottles |
Easy |
O(1) |
O(1) |
Greedy, Simulation |
|
|
| 1519 |
Number of Nodes in the Sub-Tree With the Same Label |
Medium |
O(N) |
O(N) |
Hash Table, Tree, Depth-First Search, Breadth-First Search, Counting |
|
|
| 1523 |
Count Odd Numbers in an Interval Range |
Easy |
O(1) |
O(1) |
Math |
|
|
| 1524 |
Number of Sub-arrays With Odd Sum |
Medium |
O(N) |
O(1) |
Array, Math, Dynamic Programming |
|
|
| 1525 |
Number of Good Ways to Split a String |
Medium |
O(N) |
O(N) |
String |
|
|
| 1528 |
Shuffle String |
Easy |
O(N) |
O(N) |
String |
|
|
| 1529 |
Bulb Switcher IV |
Medium |
O(N) |
O(1) |
String |
|
|
| 1530 |
Number of Good Leaf Nodes Pairs |
Medium |
O(N^2logN) |
O(N) |
Tree, DFS |
|
|
| 1533 |
Find the Index of the Large Integer |
Medium |
O(logN) |
O(1) |
Premium, Binary Search |
|
🔒 |
| 1534 |
Count Good Triplets |
Easy |
O(N^3) |
O(1) |
Array, Enumeration |
|
|
| 1535 |
Find the Winner of an Array Game |
Medium |
O(N) |
O(1) |
Array |
|
|
| 1539 |
Kth Missing Positive Number |
Easy |
O(logN) |
O(1) |
Binary Search |
|
|
| 1544 |
Make The String Great |
Easy |
O(N) |
O(N) |
String, Stack |
|
|
| 1545 |
Find Kth Bit in Nth Binary String |
Medium |
O(N^2) |
O(N^2) |
String |
Not Optimal |
|
| 1550 |
Three Consecutive Odds |
Easy |
O(N) |
O(1) |
Array |
|
|
| 1551 |
Minimum Operations to Make Array Equal |
Medium |
O(1) |
O(1) |
Math |
|
|
| 1552 |
Magnetic Force Between Two Balls |
Medium |
O(NlogN) |
O(1) |
Binary Search |
Template for Binary Search |
|
| 1556 |
Thousand Separator |
Easy |
O(N) |
O(N) |
String |
|
|
| 1557 |
Minimum Number of Vertices to Reach All Nodes |
Medium |
O(N) |
O(N) |
Graph |
|
|
| 1558 |
Minimum Numbers of Function Calls to Make Target Array |
Medium |
O(NlogK) |
O(N) |
Greedy, Simulation |
|
|
| 1560 |
Most Visited Sector in a Circular Track |
Easy |
O(N) |
O(1) |
Array |
|
|
| 1561 |
Maximum Number of Coins You Can Get |
Medium |
O(N) |
O(1) |
Sort |
|
|
| 1564 |
Put Boxes Into the Warehouse I |
Medium |
O(NlogN) |
O(N) |
Greedy |
|
🔒 |
| 1566 |
Detect Pattern of Length M Repeated K or More Times |
Easy |
O(N) |
O(1) |
Array |
|
|
| 1572 |
Matrix Diagonal Sum |
Easy |
O(N) |
O(1) |
Array |
|
|
| 1573 |
Number of Ways to Split a String |
Medium |
O(N) |
O(N) |
String |
|
|
| 1576 |
Replace All ?'s to Avoid Consecutive Repeating Characters |
Easy |
O(N) |
O(N) |
String |
|
|
| 1578 |
Minimum Deletion Cost to Avoid Repeating Letters |
Medium |
O(N) |
O(1) |
Greedy |
|
|
| 1580 |
Put Boxes Into the Warehouse II |
Medium |
O(NlogN) |
O(N) |
Greedy |
|
🔒 |
| 1582 |
Special Positions in a Binary Matrix |
Easy |
O(N) |
O(N) |
Array |
|
|
| 1583 |
Count Unhappy Friends |
Medium |
O(N^2) |
O(N^2) |
Array |
|
|
| 1588 |
Sum of All Odd Length Subarrays |
Easy |
O(N) |
O(1) |
Array |
|
|
| 1592 |
Rearrange Spaces Between Words |
Easy |
O(N) |
O(N) |
String |
|
|
| 1598 |
Crawler Log Folder |
Easy |
O(N) |
O(1) |
Stack |
|
|
| 1600 |
Throne Inheritance |
Medium |
O(N) |
O(N) |
Tree, Design |
|
|
| 1602 |
Find Nearest Right Node in Binary Tree |
Medium |
O(N) |
O(N) |
Premium, Tree, BFS |
|
🔒 |
| 1604 |
Alert Using Same Key-Card Three or More Times in a One Hour Period |
Medium |
O(NlogN) |
O(N) |
String, Ordered Map |
|
|
| 1605 |
Find Valid Matrix Given Row and Column Sums |
Medium |
O(NM) |
O(NM) |
Greedy |
|
|
| 1608 |
Special Array With X Elements Greater Than or Equal X |
Easy |
O(NlogN) |
O(N) |
Binary Search, Array |
|
|
| 1609 |
Even Odd Tree |
Easy |
O(N) |
O(N) |
Tree |
|
|
| 1614 |
Maximum Nesting Depth of the Parentheses |
Easy |
O(N) |
O(1) |
String |
|
|
| 1615 |
Maximal Network Rank |
Medium |
O(N) |
O(1) |
Graph |
|
|
| 1618 |
Maximum Font to Fit a Sentence in a Screen |
Medium |
O(logN) |
O(1) |
Premium, String, Binary Search |
|
🔒 |
| 1624 |
Largest Substring Between Two Equal Characters |
Easy |
O(N) |
O(1) |
String |
|
|
| 1625 |
Lexicographically Smallest String After Applying Operations |
Medium |
O(N*N) |
O(N) |
BFS, DFS |
|
|
| 1629 |
Slowest Key |
Easy |
O(N) |
O(1) |
String |
|
|
| 1631 |
Path With Minimum Effort |
Medium |
O(N*M*logH) |
O(M*N) |
Binary Search, DFS, BFS, Union Find, Graph |
|
|
| 1632 |
Rank Transform of a Matrix |
Hard |
O(NlogN) |
O(N) |
Array, Greedy, Union Find, Graph, Topological Sort, Matrix |
|
|
| 1634 |
Add Two Polynomials Represented as Linked Lists |
Medium |
O(N) |
O(1) |
Premium, Linked List |
|
🔒 |
| 1639 |
Number of Ways to Form a Target String Given a Dictionary |
Hard |
O(N*M) |
O(N*M) |
Dynamic Programming |
|
|
| 1640 |
Check Array Formation Through Concatenation |
Medium |
O(N) |
O(N) |
Array |
|
|
| 1641 |
Count Sorted Vowel Strings |
Medium |
O(N) |
O(1) |
Dynamic Programming, Math, Backtracking |
|
|
| 1642 |
Furthest Building You Can Reach |
Medium |
O(NlogN) |
O(N) |
Binary Search, Heap |
|
|
| 1644 |
Lowest Common Ancestor of a Binary Tree II |
Medium |
O(N) |
O(H) |
Premium, Tree |
|
🔒 |
| 1646 |
Get Maximum in Generated Array |
Easy |
O(N) |
O(N) |
Array |
|
|
| 1647 |
Minimum Deletions to Make Character Frequencies Unique |
Medium |
O(1) |
O(1) |
Greedy, Sort |
|
|
| 1650 |
Lowest Common Ancestor of a Binary Tree III |
Medium |
O(H) |
O(1) |
Premium, Tree |
|
🔒 |
| 1652 |
Defuse the Bomb |
Medium |
O(N) |
O(N) |
Array |
|
|
| 1653 |
Minimum Deletions to Make String Balanced |
Medium |
O(N) |
O(N) |
Greedy, String |
|
|
| 1656 |
Design an Ordered Stream |
Easy |
O(N) |
O(N) |
Array, Design |
|
|
| 1657 |
Determine if Two Strings Are Close |
Medium |
O(N) |
O(1) |
Greedy |
|
|
| 1658 |
Minimum Operations to Reduce X to Zero |
Medium |
O(N) |
O(N) |
Greedy, Sliding Window |
|
|
| 1663 |
Smallest String With A Given Numeric Value |
Medium |
O(N) |
O(1) |
Greedy |
|
|
| 1664 |
Ways to Make a Fair Array |
Medium |
O(N) |
O(1) |
Dynamic Programming, Greedy |
|
|
| 1673 |
Find the Most Competitive Subsequence |
Medium |
O(N) |
O(K) |
Stack, Heap, Greedy, Queue |
|
|
| 1675 |
Minimize Deviation in Array |
Hard |
O(NlogN) |
O(N) |
Array, Greedy, Heap, Ordered Set |
|
|
| 1679 |
Max Number of K-Sum Pairs |
Medium |
O(N) |
O(N) |
Hash Table |
|
|
| 1684 |
Count the Number of Consistent Strings |
Easy |
O(N) |
O(1) |
String |
|
|
| 1685 |
Sum of Absolute Differences in a Sorted Array |
Medium |
O(N) |
O(N) |
Math, Greedy |
|
|
| 1690 |
Stone Game VII |
Medium |
O(N^2) |
O(N^2) |
Dynamic Programming |
|
|
| 1695 |
Maximum Erasure Value |
Medium |
O(N) |
O(1) |
Two Pointers |
|
|
| 1696 |
Jump Game VI |
Medium |
O(N) |
O(N) |
Dequeue |
Dequeue, Monotonic Dequeue |
|
| 1700 |
Number of Students Unable to Eat Lunch |
Medium |
O(N) |
O(1) |
Array |
|
|
| 1705 |
Maximum Number of Eaten Apples |
Medium |
O(NlogN) |
O(N) |
Heap, Greedy |
|
|
| 1706 |
Where Will the Ball Fall |
Medium |
O(N*M) |
O(M) |
Dynamic Programming |
|
|
| 1710 |
Maximum Units on a Truck |
Medium |
O(NlogN) |
O(N) |
Greedy, Sort |
|
|
| 1716 |
Calculate Money in Leetcode Bank |
Easy |
O(N) |
O(1) |
Math, Greedy |
|
|
| 1721 |
Swapping Nodes in a Linked List |
Medium |
O(N) |
O(1) |
Linked List |
|
|
| 1725 |
Number Of Rectangles That Can Form The Largest Square |
Easy |
O(N) |
O(1) |
Greedy |
|
|
| 1726 |
Tuple with Same Product |
Medium |
O(N^2) |
O(N) |
Array, Hash Table |
|
|
| 1732 |
Find the Highest Altitude |
Easy |
O(N) |
O(1) |
Array |
|
|
| 1736 |
Latest Time by Replacing Hidden Digits |
Easy |
O(1) |
O(1) |
String, Greedy |
|
|
| 1748 |
Sum of Unique Elements |
Easy |
O(N) |
O(N) |
Array, Hash Table |
|
|
| 1749 |
Maximum Absolute Sum of Any Subarray |
Medium |
O(N) |
O(1) |
Greedy |
|
|
| 1750 |
Minimum Length of String After Deleting Similar Ends |
Medium |
O(N) |
O(1) |
Two Pointers |
|
|
| 1752 |
Check if Array Is Sorted and Rotated |
Easy |
O(N) |
O(1) |
Array |
|
|
| 1753 |
Maximum Score From Removing Stones |
Medium |
O(1) |
O(1) |
Math, Heap |
|
|
| 1758 |
Minimum Changes To Make Alternating Binary String |
Easy |
O(N) |
O(1) |
Array, Greedy |
|
|
| 1759 |
Count Number of Homogenous Substrings |
Medium |
O(N) |
O(1) |
String, Greedy |
|
|
| 1763 |
Longest Nice Substring |
Easy |
O(NlogN) |
O(N) |
String |
|
|
| 1764 |
Form Array by Concatenating Subarrays of Another Array |
Medium |
O(N+M) |
O(M) |
Array, Greedy |
KMP Algorithm |
|
| 1765 |
Map of Highest Peak |
Medium |
O(N*M) |
O(N*M) |
BFS, Graph |
|
|
| 1768 |
Merge Strings Alternately |
Easy |
O(N) |
O(N) |
String |
|
|
| 1769 |
Minimum Number of Operations to Move All Balls to Each Box |
Medium |
O(N) |
O(N) |
Array, Greedy |
|
|
| 1773 |
Count Items Matching a Rule |
Easy |
O(N) |
O(1) |
Array, String |
|
|
| 1774 |
Closest Dessert Cost |
Medium |
O(N*M*V) |
O(M*V) |
Greedy |
|
|
| 1779 |
Find Nearest Point That Has the Same X or Y Coordinate |
Easy |
O(N) |
O(1) |
Array |
|
|
| 1780 |
Check if Number is a Sum of Powers of Three |
Medium |
O(logN) |
O(1) |
Math, Backtracking, Recursion |
|
|
| 1781 |
Sum of Beauty of All Substrings |
Medium |
O(N^2) |
O(1) |
Hash Table, String |
|
|
| 1784 |
Check if Binary String Has at Most One Segment of Ones |
Easy |
O(N) |
O(1) |
Greedy |
|
|
| 1791 |
Find Center of Star Graph |
Medium |
O(1) |
O(1) |
Graph |
|
|
| 1792 |
Maximum Average Pass Ratio |
Medium |
O(N+KlogN) |
O(N) |
Heap |
|
|
| 1797 |
Design Authentication Manager |
Medium |
O(Design) |
O(N) |
Hash Table, Design |
|
|
| 1807 |
Evaluate the Bracket Pairs of a String |
Medium |
O(N) |
O(1) |
Array, Hash Table, String |
|
|
| 1812 |
Determine Color of a Chessboard Square |
Easy |
O(1) |
O(1) |
Math, String |
|
|
| 1816 |
Truncate Sentence |
Easy |
O(N) |
O(1) |
String |
|
|
| 1818 |
Minimum Absolute Sum Difference |
Medium |
O(NlogN) |
O(sort) |
Binary Search, Greedy |
|
|
| 1827 |
Minimum Operations to Make the Array Increasing |
Easy |
O(N) |
O(1) |
Array, Greedy |
|
|
| 1828 |
Queries on Number of Points Inside a Circle |
Medium |
O(N*M) |
O(M) |
Math |
|
|
| 1832 |
Check if the Sentence Is Pangram |
Easy |
O(N) |
O(1) |
String |
|
|
| 1833 |
Maximum Ice Cream Bars |
Medium |
O(NlogN) |
O(sort) |
Array, Sort |
|
|
| 1837 |
Sum of Digits in Base K |
Medium |
O(logN) |
O(1) |
Math, Bit Manipulation |
|
|
| 1839 |
Longest Substring Of All Vowels in Order |
Medium |
O(N) |
O(1) |
Two Pointers, String |
|
|
| 1844 |
Replace All Digits with Characters |
Easy |
O(N) |
O(N) |
String |
|
|
| 1845 |
Seat Reservation Manager |
Medium |
O(logN) |
O(N) |
Heap, Design |
|
|
| 1846 |
Maximum Element After Decreasing and Rearranging |
Medium |
O(N) |
O(N) |
Array, Greedy, Sorting |
|
|
| 1848 |
Minimum Distance to the Target Element |
Easy |
O(N) |
O(1) |
Array |
|
|
| 1854 |
Maximum Population Year |
Easy |
O(NlogN) |
O(N) |
Array, Counting |
|
|
| 1859 |
Sorting the Sentence |
Easy |
O(N) |
O(N) |
String, Sorting |
|
|
| 1860 |
Incremental Memory Leak |
Medium |
O(logN) |
O(1) |
Math |
|
|
| 1861 |
Rotating the Box |
Medium |
O(R*C) |
O(1) |
Array, Two Pointers |
|
|
| 1864 |
Minimum Number of Swaps to Make the Binary String Alternating |
Medium |
O(N) |
O(N) |
String, Greedy |
|
|
| 1877 |
Minimize Maximum Pair Sum in Array |
Medium |
O(NlogN) |
O(Sort) |
Array, Two Pointers, Greedy, Sorting |
|
|
| 1897 |
Redistribute Characters to Make All Strings Equal |
Easy |
O(N) |
O(N) |
Hash Table, String, Couting |
|
|
| 1899 |
Merge Triplets to Form Target Triplet |
Medium |
O(N) |
O(1) |
Greedy, Array |
|
|
| 1903 |
Largest Odd Number in String |
Easy |
O(N) |
O(1) |
Math, String, Greedy |
|
|
| 1905 |
Count Sub Islands |
Medium |
O(R*C) |
O(R*C) |
Array, DFS, BFS, Union-Find, Matrix |
|
|
| 1911 |
Maximum Alternating Subsequence Sum |
Medium |
O(N) |
O(1) |
Array, Dynamic Programming, Greedy |
|
|
| 1920 |
Build Array from Permutation |
Easy |
O(N) |
O(1) |
Array, Simulation |
|
|
| 1929 |
Concatenation of Array |
Easy |
O(N) |
O(1) |
Array |
|
|
| 1962 |
Remove Stones to Minimize the Total |
Medium |
O(KlogN) |
O(N) |
Array, Heap |
|
|
| 1963 |
Minimum Number of Swaps to Make the String Balanced |
Medium |
O(N) |
O(1) |
Two Pointers,String,Stack,Greedy |
|
|
| 1971 |
Find if Path Exists in Graph |
Easy |
O(N) |
O(N) |
BFS, DFS, Graph |
|
|
| 1974 |
Minimum Time to Type Word Using Special Typewriter |
Easy |
O(N) |
O(1) |
String, Greedy |
|
|
| 1980 |
Find Unique Binary String |
Medium |
O(NlogN) |
O(N) |
String, Binary Search |
|
|
| 1991 |
Find the Middle Index in Array |
Easy |
O(N) |
O(N) |
Array, Prefix Sum |
|
|
| 1992 |
Find All Groups of Farmland |
Medium |
O(R*C) |
O(R*C) |
Array, DFS, BFS, Matrix |
|
|
| 1995 |
Count Special Quadruplets |
Easy |
O(N^2) |
O(N^2) |
Array, Enumeration |
|
|
| 1996 |
The Number of Weak Characters in the Game |
Medium |
O(NlogN) |
O(N) |
Array, Stack, Greedy, Sorting, Monotonic Stack |
|
|
| 2000 |
Reverse Prefix of Word |
Easy |
O(N) |
O(1) |
Two Pointers, String |
|
|
| 2024 |
Maximize the Confusion of an Exam |
Medium |
O(N) |
O(1) |
String, Binary Search, Sliding Window, Prefix Sum |
|
|
| 2038 |
Remove Colored Pieces if Both Neighbors are the Same Color |
Medium |
O(N) |
O(1) |
Math, String, Greedy, Game Theory |
|
|
| 2039 |
The Time When the Network Becomes Idle |
Medium |
O(V+E) |
O(V+E) |
Array, BFS, Graph |
|
|
| 2042 |
Check if Numbers Are Ascending in a Sentence |
Easy |
O(N) |
O(1) |
String |
|
|
| 2043 |
Simple Bank System |
Medium |
Design |
Design |
Array, Hash Table, Design, Simulation |
|
|
| 2049 |
Count Nodes With the Highest Score |
Medium |
O(N) |
O(N) |
Array, Tree, Depth-First Search, Binary Tree |
|
|
| 2062 |
Count Vowel Substrings of a String |
Easy |
O(N^3) |
O(N) |
Hash Table, String |
|
|
| 2073 |
Time Needed to Buy Tickets |
Easy |
O(N) |
O(1) |
Array, Queue, Simulation |
|
|
| 2074 |
Reverse Nodes in Even Length Groups |
Medium |
O(N) |
O(N) |
Linked List |
|
|
| 2085 |
Count Common Words With One Occurrence |
Easy |
O(N) |
O(N) |
Array, Hash Table, String, Counting |
|
|
| 2087 |
Minimum Cost Homecoming of a Robot in a Grid |
Medium |
O(N) |
O(1) |
Array, Greedy, Matrix |
|
|
| 2091 |
Removing Minimum and Maximum From Array |
Medium |
O(N) |
O(1) |
Greedy, Array |
|
|
| 2094 |
Finding 3-Digit Even Numbers |
Easy |
O(N) |
O(N) |
Array, Hash Table, Sorting, Enumeration |
|
|
| 2095 |
Delete the Middle Node of a Linked List |
Medium |
O(N) |
O(1) |
Linked List |
|
|
| 2096 |
Step-By-Step Directions From a Binary Tree Node to Another |
Medium |
O(N) |
O(N) |
String, Tree, Depth-First Search, Binary Tree |
|
|
| 2099 |
Find Subsequence of Length K With the Largest Sum |
Medium |
O(NlogK) |
O(K) |
Array, Hash Table, Sotring, Heap |
|
|
| 2100 |
Array, Dynamic Programming, Prefix Sum |
Medium |
O(N) |
O(N) |
Array, Dynamic Programming, Prefix Sum |
|
|
| 2101 |
Detonate the Maximum Bombs |
Medium |
O(E+V) |
O(E+V) |
Array, Math, DFS, BFS, Graph, Geometry |
|
|
| 2103 |
Rings and Rods |
Easy |
O(N) |
O(N) |
Hash Table, String |
|
|
| 2119 |
A Number After a Double Reversal |
Easy |
O(1) |
O(1) |
Math |
|
|
| 2120 |
Execution of All Suffix Instructions Staying in a Grid |
Medium |
O(S) |
O(S) |
String, Simulation |
|
|
| 2121 |
Intervals Between Identical Elements |
Medium |
O(N) |
O(N) |
Array, Hash Table, Prefix Sum |
|
|
| 2136 |
Earliest Possible Day of Full Bloom |
Hard |
O(Sort) |
O(Sort) |
Array, Greedy, Sorting |
|
|
| 2138 |
Divide a String Into Groups of Size k |
Easy |
O(N) |
O(N) |
String, Simulation |
|
|
| 2139 |
Minimum Moves to Reach Target Score |
Medium |
O(logN) |
O(1) |
Math, Greedy |
|
|
| 2140 |
Solving Questions With Brainpower |
Medium |
O(N) |
O(N) |
Array, Dynamic Programming |
|
|
| 2165 |
Smallest Value of the Rearranged Number |
Medium |
O(logN) |
O(logN) |
Math, Sorting |
|
|
| 2176 |
Count Equal and Divisible Pairs in an Array |
Easy |
O(N^2) |
O(1) |
Array |
|
|
| 2177 |
Find Three Consecutive Integers That Sum to a Given Number |
Medium |
O(1) |
O(1) |
Math, Binary Search |
|
|
| 2180 |
Count Integers With Even Digit Sum |
Easy |
O(1) |
O(1) |
Math, Simulation |
|
|
| 2185 |
Counting Words With a Given Prefix |
Easy |
O(N) |
O(1) |
Array, String |
|
|
| 2186 |
Minimum Number of Steps to Make Two Strings Anagram II |
Medium |
O(N) |
O(N) |
Hash Table, String, Counting |
|
|
| 2190 |
Most Frequent Number Following Key In an Array |
Easy |
O(N) |
O(N) |
Array, Hash Table, Counting |
|
|
| 2191 |
Sort the Jumbled Numbers |
Medium |
O(NlogN) |
O(1) |
Array, Sorting |
|
|
| 2192 |
All Ancestors of a Node in a Directed Acyclic Graph |
Medium |
O(N+V) |
O(U+V) |
DFS, BFS, Topological Sort, Graph |
|
|
| 2196 |
Create Binary Tree From Descriptions |
Medium |
O(N) |
O(N) |
DFS, BFS, Binary Tree, Tree, Hash Table, Array |
|
|
| 2244 |
Minimum Rounds to Complete All Tasks |
Medium |
O(N) |
O(N) |
Array, Hash Table, Greedy, Counting |
|
|
| 2270 |
Number of Ways to Split Array |
Medium |
O(N) |
O(N) |
Array, Prefix Sum |
|
|
| 2303 |
Calculate Amount Paid in Taxes |
Easy |
O(N) |
O(1) |
Array, Simulation |
|
|
| 2336 |
Smallest Number in Infinite Set |
Medium |
O(Design) |
O(Design) |
Hash Table, Design, Heap (Priority Queue) |
|
|
| 2347 |
Best Poker Hand |
Easy |
O(1) |
O(1) |
Array, Hash Table, Counting |
|
|
| 2359 |
Find Closest Node to Given Two Nodes |
Medium |
O(N) |
O(N) |
DFS, Graph |
|
|
| 2368 |
Reachable Nodes With Restrictions |
Medium |
O(V + E) |
O(V + E) |
Array, Hash Table, Tree, BFS, DFS, Graph |
|
|
| 2370 |
Longest Ideal Subsequence |
Medium |
O(N) |
O(N) |
Hash Table, String, Dynamic Programming |
|
|
| 2389 |
Longest Subsequence With Limited Sum |
Easy |
O(NlogN) |
O(N) |
Array, Binary Search, Greedy, Sorting, Prefix Sum |
|
|
| 2476 |
Closest Nodes Queries in a Binary Search Tree |
Medium |
O(NlogN) |
O(N) |
Array, Binary Search, Tree, Depth-First Search, Binary Search Tree, Binary Tree |
|
|
| 2487 |
Remove Nodes From Linked List |
Medium |
O(N) |
O(N) |
Linked List, Stack, Recursion, Monotonic Stack |
|
|
| 2498 |
Frog Jump II |
Medium |
O(N) |
O(1) |
Array, Binary Search, Greedy |
|
|
| 2502 |
Design Memory Allocator |
Medium |
Design |
Design |
Array, Hash Table, Design, Simulation |
|
|
| 2517 |
Maximum Tastiness of Candy Basket |
Medium |
O(NlogN) |
O(1) |
Array, Binary Search, Sorting |
|
|
| 2571 |
Minimum Operations to Reduce an Integer to 0 |
Medium |
O(logN) |
O(logN) |
Dynamic Programming, Greedy, Bit Manipulation |
|
|
| 2583 |
Kth Largest Sum in a Binary Tree |
Medium |
O(NlogN) |
O(N) |
Tree, Breadth-First Search, Sorting, Binary Tree |
|
|
| 2641 |
Cousins in Binary Tree II |
Medium |
O(N) |
O(N) |
Hash Table, Tree, Depth-First Search, Breadth-First Search, Binary Tree |
|
|
| 2673 |
Make Costs of Paths Equal in a Binary Tree |
Medium |
O(N) |
O(logN) |
Array, Dynamic Programming, Greedy, Tree, Binary Tree |
|
|
| 2812 |
Find the Safest Path in a Grid |
Medium |
O(R*C) |
O(R*C) |
Array, Binary Search, Breadth-First Search, Union Find, Matrix |
|
|
| 2824 |
Count Pairs Whose Sum is Less than Target |
Easy |
O(NlogN) |
O(1) |
Array, Two Pointers, Binary Search, Sorting |
|
|
| 2958 |
Length of Longest Subarray With at Most K Frequency |
Medium |
O(N) |
O(N) |
Array, Hash Table, Sliding Window |
|
|
| 2962 |
Count Subarrays Where Max Element Appears at Least K Times |
Medium |
O(N) |
O(N) |
Array, Sliding Window |
|
|
| 2966 |
Divide Array Into Arrays With Max Difference |
Medium |
O(NlogN) |
O(N) |
Array, Greedy, Sorting |
|
|
| 2971 |
Find Polygon With the Largest Perimeter |
Medium |
O(N) |
O(N) |
Array, Greedy, Sorting, Prefix Sum |
|
|
| 3005 |
Count Elements With Maximum Frequency |
Easy |
O(N) |
O(N) |
Array, Hash Table, Counting |
|
|
| 3075 |
Maximize Happiness of Selected Children |
Medium |
O(NlogK) |
O(K) |
Array, Greedy, Sorting |
|
|
| 3083 |
Existence of a Substring in a String and Its Reverse |
Easy |
O(N) |
O(N) |
Hash Table, String |
|
|
| 3084 |
Count Substrings Starting and Ending with Given Character |
Medium |
O(N) |
O(1) |
Math, String, Counting |
|
|
| 3085 |
Minimum Deletions to Make String K-Special |
Medium |
O(N) |
O(1) |
Hash Table, String, Greedy, Sorting, Counting |
|
|
| 3090 |
Maximum Length Substring With Two Occurrences |
Easy |
O(N) |
O(1) |
Hash Table, String, Sliding Window |
|
|
| 3091 |
Apply Operations to Make Sum of Array Greater Than or Equal to k |
Medium |
O(1) |
O(1) |
Math, Greedy, Enumeration |
|
|
| 3092 |
Most Frequent IDs |
Medium |
O(NlogN) |
O(N) |
Array, Hash Table, Heap (Priority Queue), Ordered Set |
Template for Sorted Container |
|
| 3105 |
Longest Strictly Increasing or Strictly Decreasing Subarray |
Easy |
O(N) |
O(1) |
|
|
|
| 3106 |
Lexicographically Smallest String After Operations With Constraint |
Medium |
O(N) |
O(N) |
|
|
|
| 3107 |
Minimum Operations to Make Median of Array Equal to K |
Medium |
O(NlogN) |
O(N) |
|
|
|