- This list was initially created for personal use
- Headers and footers of source code are generated from extension
LeetCodein VSCode
- Solve problems by topic: when you first started, it is important to understand different topics quickly and solving 10-20 problems per topic is a good way to grasp the concept.
- If you are using Python and are interested in writing Pythonic code, I created a repo for Python tips and tricks
- Always aim to get a better solution by reading the discussion after you successfully solves a problem. Leetcode's community is amazing, you will learn of lot of useful tips and tricks to make your code cleaner and faster from the discussion posts.
- Leetcode has a "Taking Note" system where you can take notes of things you learn for each problem. Make good use of it.
- Leetcode's category of difficulty (Easy, Medium, Hard) is not always correct. My rule of thumb is looking at the acceptance rate.
>55%means Easy and<35%means Hard - What is correct is the amount of likes and dislikes of a problem. Problems with more dislikes than likes are usually not worth solving. Try a different one.
- When you are stuck, there are a few things you can do to give yourself hints:
- Look at the tag for the problem and see what kind of algorithm or data structure is needed for solving
- Look at the hints provided by Leetcode
- Quickly look at the discussion title to see what the expected complexity is or the name of the algorithm.
- Estimate the Time Complexity of the problem based on the input constraints (see next tip)
- You can estimate the Time complexity based on the input constraints as follows:
| input size | estimated time complexity |
|---|---|
N <= 10 |
O(N!) |
N <= 20 |
O(2^N) |
N <= 10^2 |
O(N^3) |
N <= 10^3 |
O(N^2) |
N <= 10^4 |
O(NlogN) |
N <= 10^6 |
O(N) |
N > 10^6 |
O(1) or O(logN) |
| # | Title | Level | Time | Space | Tags | Note | Premium 🔒 |
|---|---|---|---|---|---|---|---|
| 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) |
- Important and Useful links from all over the LeetCode
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- Graph
- Template for Hard String Problems
- Powerful studying program for Beginners and Intermediate levels. All common mistakes analyzed.
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