LeetCode Questions List
LeetCode Questions List
This page contains a comprehensive list of all LeetCode problems solved in this blog, organized by difficulty level, category, and solution approach.
Summary Statistics
- Total Problems: 307
- Easy: 57 problems
- Medium: 217 problems
- Hard: 33 problems
Problems by Category
Counts are computed from the Category + Solution Approach columns in the full table by tag matching (a problem can appear in multiple categories).
- Array & Matrix: Array & Matrix, Arrays & Strings
- String Processing: String Processing
- Linked List: Linked List
- Trees & Binary Trees: Trees, DFS, BFS
- Dynamic Programming: Dynamic Programming
- Backtracking: Backtracking
- Monotonic Stack / Queue: Stack
- Graph & Union Find: Graph
- Data Structure Design: Data Structure Design
- Intervals & Sweep Line: Greedy
- Math & Bit Manipulation: Math & Bit Manipulation
- Heap / Priority Queue: Heap
- Search: Search
See the All LeetCode Problems table below for concrete problems in each category.
Solution Approaches Summary
Most Common Approaches
- Dynamic Programming (DP) - template
- Monotonic Stack - template
- Binary Search - template
- Hash Map/Set - template
- DFS/BFS - DFS template, BFS template
- Backtracking - template
- Sliding Window - template
- Two Pointers - template
- Trie - template
- Union Find - template
- Sweep Line - template
- Data Structure Design - template
Tips for Problem Solving
- Identify the Pattern: Look for common algorithm patterns (DP, sliding window, etc.)
- Start Simple: Begin with brute force, then optimize
- Use Data Structures: Choose appropriate DS for the problem
- Consider Edge Cases: Handle boundary conditions
- Optimize Space/Time: Trade-offs between complexity and efficiency
Last updated: April 15, 2026 Total problems solved: 307
All LeetCode Problems
| Problem | Title | Difficulty | Category | Date Added |
|---|---|---|---|---|
| 2 | Add Two Numbers | Medium | Linked List, Recursion | 2025-11-18 |
| 3 | Longest Substring Without Repeating Characters | Medium | Sliding Window, Hash Map, String, Two Pointers | 2025-10-09 |
| 5 | Longest Palindromic Substring | Medium | String, Two Pointers, Dynamic Programming | 2026-01-08 |
| 18 | 4Sum | Medium | Arrays, Two Pointers, Sorting | 2025-11-04 |
| 20 | Valid Parentheses | Easy | String, Stack | 2025-11-04 |
| 22 | Generate Parentheses | Medium | String, Backtracking, Recursion | 2026-01-12 |
| 23 | Swap Nodes in Pairs | Medium | Linked List, Recursive, Data Structures, Pointers, Swap Nodes, Recursion, Iterative | 2025-09-24 |
| 23 | Merge k Sorted Lists | Hard | Linked List, Divide And Conquer, Heap | 2026-02-15 |
| 25 | Reverse Nodes in k-Group | Hard | Linked List, Recursive, Data Structures, Pointers, Reverse Nodes, K Group, Recursion | 2025-09-24 |
| 27 | Remove Element | Easy | Array, Two Pointers | 2026-01-26 |
| 29 | Divide Two Integers | Medium | Math, Bit Manipulation | 2026-02-14 |
| 32 | Longest Valid Parentheses | Hard | String, Dynamic Programming, Stack | 2025-11-24 |
| 33 | Search in Rotated Sorted Array | Medium | Binary Search, Data Structures, Array, Rotated Array, Search | 2025-09-23 |
| 34 | Find First and Last Position of Element in Sorted Array | Medium | Array, Binary Search | 2026-01-30 |
| 35 | Search Insert Position | Easy | Array, Binary Search | 2026-01-30 |
| 36 | Valid Sudoku | Medium | Math, Bit Manipulation | 2026-02-14 |
| 38 | Count and Say | Medium | String, Simulation | 2026-02-16 |
| 42 | Trapping Rain Water | Hard | Two Pointers, Stack, Dp | 2026-02-17 |
| 43 | Multiply Strings | Medium | String, Math, Simulation | 2026-02-17 |
| 44 | Wildcard Matching | Hard | String, Dynamic Programming, Greedy, Two Pointers | 2026-02-01 |
| 45 | Jump Game II | Medium | Array, Greedy | 2025-11-18 |
| 46 | Permutations | Medium | Backtracking, Recursion | 2025-10-20 |
| 47 | Permutations II | Medium | Backtracking, Recursion, Duplicates | 2025-10-20 |
| 48 | Rotate Image | Medium | Matrix, Data Structures, 2D Array, Transformation, Rotate Image, In Place | 2025-09-24 |
| 49 | Group Anagrams | Medium | String, Hash Table | 2025-11-18 |
| 50 | Pow(x, n) | Medium | Math, Data Structures, Recursion, Bit Manipulation, Pow | 2025-09-25 |
| 51 | N-Queens | Hard | Array, Backtracking, Recursion | 2026-01-12 |
| 53 | Maximum Subarray | Medium | Array, Dynamic Programming, Greedy, Divide And Conquer | 2026-01-04 |
| 54 | Spiral Matrix | Medium | Matrix, Data Structures, Simulation, Traversal, Spiral Matrix | 2025-09-25 |
| 55 | Jump Game | Medium | Array, Greedy, Dynamic Programming | 2026-01-03 |
| 56 | Merge Intervals | Medium | Array, Sorting, Interval | 2025-11-24 |
| 59 | Spiral Matrix II | Medium | Matrix, Simulation | 2026-02-18 |
| 62 | Unique Paths | Medium | Dynamic Programming, Data Structures, Grid, Combinatorics, Unique Paths | 2025-09-24 |
| 63 | Unique Paths II | Medium | Array, Dynamic Programming, Matrix | 2026-01-21 |
| 64 | Minimum Path Sum | Medium | Array, Dynamic Programming, Matrix | 2026-01-10 |
| 67 | Add Binary | Easy | String, Math, Bit Manipulation | 2025-12-11 |
| 73 | Set Matrix Zeroes | Medium | Matrix, Array | 2026-04-02 |
| 75 | Sort Colors | Medium | Array, Two Pointers, Sorting | 2025-12-02 |
| 77 | Combinations | Medium | Backtracking, Data Structures, Recursion, Combinations, Dfs | 2025-09-29 |
| 77 | Combinations | Medium | Backtracking, Recursion, Combinations | 2025-10-20 |
| 78 | Subsets | Medium | Backtracking | 2026-03-05 |
| 79 | Word Search | Medium | Array, Backtracking, Matrix, Dfs | 2026-01-12 |
| 84 | Largest Rectangle in Histogram | Hard | Stack, Monotonic Stack | 2025-10-20 |
| 89 | Gray Code | Medium | Backtracking, Data Structures, Recursion, Bit Manipulation, Gray Code | 2025-09-25 |
| 91 | Decode Ways | Medium | Dynamic Programming | 2026-02-09 |
| 93 | Restore IP Addresses | Medium | Backtracking, String | 2025-11-14 |
| 94 | Binary Tree Inorder Traversal | Easy | Tree, Dfs | 2026-03-06 |
| 96 | Unique Binary Search Trees | Medium | Dynamic Programming, Data Structures, Math, Catalan Numbers, Binary Search Trees | 2025-10-03 |
| 100 | Same Tree | Easy | Tree, Dfs | 2026-01-19 |
| 101 | Symmetric Tree | Easy | Tree, Dfs | 2026-01-19 |
| 102 | Binary Tree Level Order Traversal | Medium | Tree, Bfs, Binary Tree | 2026-01-07 |
| 103 | Binary Tree Zigzag Level Order Traversal | Medium | Tree, Bfs, Binary Tree | 2026-01-06 |
| 104 | Maximum Depth of Binary Tree | Easy | Tree, Dfs | 2026-01-19 |
| 110 | Balanced Binary Tree | Easy | Tree, Dfs | 2026-03-06 |
| 111 | Minimum Depth of Binary Tree | Easy | Tree, Dfs | 2026-01-19 |
| 112 | Path Sum | Easy | Tree, Dfs | 2026-01-19 |
| 112 | Path Sum | Easy | Tree, Dfs | 2026-03-06 |
| 113 | Path Sum II | Medium | Tree, Dfs, Backtracking | 2026-03-06 |
| 122 | Best Time to Buy and Sell Stock II | Medium | Array, Greedy, Dynamic Programming | 2026-01-03 |
| 129 | Sum Root to Leaf Numbers | Medium | Tree, Dfs | 2025-11-24 |
| 131 | Palindrome Partitioning | Medium | Backtracking, Data Structures, String, Palindrome, Recursion, Partitioning | 2025-09-30 |
| 133 | Clone Graph | Medium | Graph, Dfs, Bfs, Clone | 2025-10-20 |
| 134 | Gas Station | Medium | Greedy, Array | 2026-03-22 |
| 135 | Candy | Hard | Array, Greedy | 2026-01-04 |
| 144 | Binary Tree Preorder Traversal | Easy | Tree, Dfs | 2026-03-06 |
| 145 | Binary Tree Postorder Traversal | Easy | Tree, Dfs | 2026-03-06 |
| 146 | LRU Cache | Medium | Design, Data Structures, Hash Map, Linked List | 2025-11-14 |
| 146 | LRU Cache | Medium | Design, Data Structures, Hash Map, Linked List | 2025-11-16 |
| 146 | LRU Cache | Medium | Design, Data Structures, Hash Map, Linked List | 2025-12-02 |
| 150 | Evaluate Reverse Polish Notation | Medium | Stack, Data Structures, Mathematical Expression, Reverse Polish Notation, Rpn | 2025-09-24 |
| 151 | Reverse Words in a String | Medium | String, Two Pointers | 2026-03-27 |
| 155 | Min Stack | Medium | Stack | 2026-02-11 |
| 162 | Find Peak Element | Medium | Array, Binary Search | 2026-01-30 |
| 189 | Rotate Array | Medium | Array | 2026-01-20 |
| 198 | House Robber | Medium | Dynamic Programming, Dp | 2025-11-18 |
| 200 | Number of Islands | Medium | Dfs, Graph, Matrix | 2025-11-20 |
| 203 | Remove Linked List Elements | Easy | Linked List, Iteration | 2025-11-18 |
| 206 | Reverse Linked List | Easy | Linked List, Recursion, Iteration | 2025-11-16 |
| 207 | Course Schedule | Medium | Graph, Topological Sort, Cycle Detection | 2025-10-20 |
| 208 | Implement Trie (Prefix Tree) | Medium | String, Design, Trie | 2026-01-18 |
| 209 | Minimum Size Subarray Sum | Medium | Array, Sliding Window, Binary Search, Prefix Sum | 2026-01-26 |
| 210 | Course Schedule II | Medium | Graph, Topological Sort | 2026-02-08 |
| 211 | Design Add and Search Words Data Structure | Medium | String, Design, Trie | 2026-01-18 |
| 211 | Design Add and Search Words Data Structure | Medium | String, Design, Trie | 2026-01-19 |
| 213 | House Robber II | Medium | Array, Dynamic Programming | 2026-01-25 |
| 215 | Kth Largest Element in an Array | Medium | Array, Heap, Quickselect, Divide And Conquer | 2026-01-05 |
| 217 | Contains Duplicate | Easy | Array, Hash | 2026-03-07 |
| 218 | The Skyline Problem | Hard | Sweep Line, Priority Queue, Data Structures, Union Find | 2025-10-05 |
| 219 | Contains Duplicate II | Easy | Array, Hash, Sliding Window | 2026-03-07 |
| 224 | Basic Calculator | Medium | String, Stack, Expression Evaluation | 2025-11-13 |
| 226 | Invert Binary Tree | Easy | Tree, Dfs | 2026-01-19 |
| 227 | Basic Calculator II | Medium | String, Stack, Expression Evaluation | 2025-11-13 |
| 236 | Lowest Common Ancestor of a Binary Tree | Medium | Tree, Dfs | 2026-01-19 |
| 238 | Product of Array Except Self | Medium | Array, Prefix Sum, Two Pointers | 2026-01-27 |
| 239 | Sliding Window Maximum | Hard | Arrays, Deque, Sliding Window, Monotonic Queue | 2025-11-04 |
| 240 | Search a 2D Matrix II | Medium | Binary Search, Matrix, 2D Array, Divide Conquer, Search, Optimization | 2025-10-06 |
| 242 | Valid Anagram | Easy | String, Hash | 2026-03-07 |
| 249 | Group Shifted Strings | Medium | String, Hash | 2026-03-07 |
| 252 | Meeting Rooms | Easy | Array, Sorting, Intervals | 2026-02-06 |
| 253 | Meeting Rooms II | Medium | Array, Sorting, Priority Queue, Two Pointers | 2025-12-11 |
| 260 | Single Number III | Medium | Bit Manipulation | 2026-03-31 |
| 261 | Graph Valid Tree | Medium | Graph, Dsu, Dfs | 2026-04-01 |
| 269 | Alien Dictionary | Hard | Graph, Topological Sort, String | 2026-01-14 |
| 270 | Closest Binary Search Tree Value | Easy | Binary Search Tree, Tree, Recursion, Binary Search | 2025-12-30 |
| 277 | Find the Celebrity | Medium | Graph, Two Pointers | 2025-11-24 |
| 279 | Perfect Squares | Medium | Math, Dynamic Programming, Bfs | 2025-12-14 |
| 281 | Zigzag Iterator | Medium | Design, Iterator | 2025-12-10 |
| 285 | Inorder Successor in BST | Medium | Binary Search Tree, Tree, Inorder Traversal | 2025-12-30 |
| 286 | Walls and Gates | Medium | Array, Matrix, Bfs | 2025-12-14 |
| 300 | Longest Increasing Subsequence | Medium | Dynamic Programming, Dp, Binary Search | 2025-10-17 |
| 303 | Range Sum Query - Immutable | Easy | Array, Design, Prefix Sum | 2026-01-01 |
| 305 | Number of Islands II | Hard | Array, Union Find, Graph | 2026-01-16 |
| 307 | Range Sum Query - Mutable | Medium | Array, Segment Tree, Binary Indexed Tree | 2026-01-16 |
| 308 | Range Sum Query 2D - Mutable | Hard | Design, Data Structures, Prefix Sum, Matrix | 2025-12-31 |
| 309 | Best Time to Buy and Sell Stock with Cooldown | Medium | Dp | 2026-03-20 |
| 310 | Minimum Height Trees | Medium | Graph, Tree, Topological Sort, Bfs | 2026-01-14 |
| 314 | Binary Tree Vertical Order Traversal | Medium | Tree, Bfs, Vertical Order | 2025-10-20 |
| 315 | Count of Smaller Numbers After Self | Hard | Array, Binary Search, Divide And Conquer, Binary Indexed Tree, Segment Tree, Merge Sort | 2026-01-15 |
| 315 | Count of Smaller Numbers After Self | Hard | Array, Binary Search, Divide And Conquer, Binary Indexed Tree, Segment Tree, Merge Sort | 2026-01-17 |
| 316 | Remove Duplicate Letters | Medium | Stack, Monotonic Stack, Greedy | 2025-10-17 |
| 317 | Shortest Distance from All Buildings | Hard | Bfs, Graph, Data Structures, Matrix, Shortest Path, Shortest Distance, Buildings | 2025-09-24 |
| 322 | Coin Change | Medium | Dynamic Programming, Dp, Coin Change | 2025-10-20 |
| 323 | Number of Connected Components in an Undirected Graph | Medium | Graph, Bfs, Dfs, Union Find | 2026-01-07 |
| 324 | Wiggle Sort II | Medium | Arrays, Nth Element, Three Way Partition, Index Mapping | 2025-11-04 |
| 325 | Maximum Size Subarray Sum Equals k | Medium | Array, Hash Table, Prefix Sum | 2026-02-01 |
| 327 | Count of Range Sum | Hard | Array, Divide And Conquer | 2026-01-20 |
| 341 | Flatten Nested List Iterator | Medium | Design, Stack, Iterator | 2026-03-24 |
| 344 | Reverse String | Easy | Two Pointers, String | 2025-10-29 |
| 346 | Moving Average from Data Stream | Easy | Queue, Sliding Window, Design | 2025-12-14 |
| 347 | Top K Frequent Elements | Medium | Array, Hash Table, Heap | 2025-10-21 |
| 348 | Design Tic-Tac-Toe | Medium | Design, Array | 2025-10-21 |
| 348 | Design Tic-Tac-Toe | Medium | Design, Matrix | 2026-03-04 |
| 349 | Intersection of Two Arrays | Easy | Array, Hash Table | 2026-01-19 |
| 351 | Android Unlock Patterns | Medium | Backtracking, Recursion, Dynamic Programming | 2026-01-02 |
| 354 | Russian Doll Envelopes | Medium | Array, Dynamic Programming, Binary Search, Sorting | 2026-01-25 |
| 360 | Sort Transformed Array | Medium | Array, Two Pointers, Math, Parabola | 2025-12-31 |
| 362 | Design Hit Counter | Medium | Design, Queue | 2026-03-18 |
| 376 | Wiggle Subsequence | Medium | Array, Dynamic Programming, Greedy | 2026-01-04 |
| 382 | Linked List Random Node | Medium | Linked List, Randomized | 2026-04-08 |
| 383 | Ransom Note | Easy | String, Hash | 2026-03-07 |
| 387 | First Unique Character in a String | Easy | String, Hash Table | 2026-01-19 |
| 389 | Find the Difference | Easy | Bit Manipulation, String | 2026-03-27 |
| 392 | Is Subsequence | Easy | String, Two Pointers, Greedy, Dynamic Programming | 2026-01-03 |
| 393 | UTF-8 Validation | Medium | Bit Manipulation, String, Array | 2025-12-31 |
| 394 | Decode String | Medium | Stack, String Processing | 2025-10-19 |
| 398 | Random Pick Index | Medium | Hash Table, Reservoir Sampling | 2025-11-24 |
| 399 | Evaluate Division | Medium | Disjoint Set, Graph, Dfs | 2025-12-17 |
| 406 | Queue Reconstruction by Height | Medium | Greedy, Sorting, List | 2025-10-19 |
| 408 | Valid Word Abbreviation | Easy | String, Two Pointers | 2025-11-24 |
| 409 | Longest Palindrome | Easy | String, Hash Table, Greedy | 2026-01-18 |
| 409 | Longest Palindrome | Easy | String, Hash Table, Greedy | 2026-01-19 |
| 416 | Partition Equal Subset Sum | Medium | Dynamic Programming | 2026-02-11 |
| 417 | Pacific Atlantic Water Flow | Medium | Dfs, Bfs, Graph | 2025-10-19 |
| 418 | Sentence Screen Fitting | Medium | Dynamic Programming, String, Simulation | 2025-12-31 |
| 419 | Battleships in a Board | Medium | Array, Matrix | 2025-10-21 |
| 425 | Word Squares | Hard | Backtracking, Trie, Recursion, String | 2025-12-31 |
| 426 | Convert Binary Search Tree to Sorted Doubly Linked List | Medium | Tree, Linked List | 2025-10-22 |
| 429 | N-ary Tree Level Order Traversal | Medium | Tree, Bfs, N Ary Tree | 2026-01-07 |
| 433 | Minimum Genetic Mutation | Medium | Bfs, String | 2026-03-15 |
| 435 | Non-overlapping Intervals | Medium | Array, Greedy, Sorting, Intervals, Dynamic Programming | 2026-01-03 |
| 437 | Path Sum III | Medium | Tree, Dfs, Recursion | 2025-10-19 |
| 452 | Minimum Number of Arrows to Burst Balloons | Medium | Array, Greedy, Sorting, Intervals | 2026-01-03 |
| 455 | Assign Cookies | Easy | Array, Greedy, Sorting, Two Pointers | 2026-01-03 |
| 460 | LFU Cache | Hard | Design, Data Structures, Hash Map, Linked List | 2025-11-14 |
| 480 | Sliding Window Median | Hard | Arrays, Multiset, Sliding Window, Two Heaps | 2025-11-04 |
| 485 | Max Consecutive Ones | Easy | Arrays, Sliding Window | 2025-11-04 |
| 487 | Max Consecutive Ones II | Medium | Array, Dynamic Programming, Sliding Window | 2025-12-30 |
| 489 | Robot Room Cleaner | Hard | Dfs, Backtracking | 2025-11-24 |
| 494 | Target Sum | Medium | Dynamic Programming, Dp, Subset Sum | 2025-10-15 |
| 496 | Next Greater Element I | Easy | Array, Stack, Monotonic Stack, Hash Table | 2025-12-31 |
| 498 | Diagonal Traverse | Medium | Array, Matrix, Simulation | 2026-01-20 |
| 503 | Next Greater Element II | Medium | Monotonic Stack, Stack | 2025-10-17 |
| 509 | Fibonacci Number | Easy | Dynamic Programming, Recursion | 2025-11-18 |
| 523 | Continuous Subarray Sum | Medium | Prefix Sum, Hash | 2026-03-04 |
| 525 | Contiguous Array | Medium | Arrays, Hash Map, Prefix Sum | 2025-11-04 |
| 528 | Random Pick with Weight | Medium | Design, Binary Search, Prefix Sum | 2025-11-24 |
| 532 | K-diff Pairs in an Array | Medium | Array, Hash Table | 2026-02-06 |
| 543 | Diameter of Binary Tree | Easy | Tree, Dfs | 2026-03-06 |
| 545 | Boundary of Binary Tree | Medium | Tree, Dfs | 2025-10-21 |
| 547 | Number of Provinces | Medium | Disjoint Set, Dfs, Graph | 2025-12-18 |
| 560 | Subarray Sum Equals K | Medium | Array, Hash Table, Prefix Sum | 2026-02-01 |
| 561 | Array Partition | Easy | Array, Greedy, Sorting | 2026-01-03 |
| 568 | Maximum Vacation Days | Hard | Dynamic Programming, Graph, Optimization | 2025-12-31 |
| 593 | Valid Square | Medium | Math, Geometry | 2025-12-02 |
| 616 | Add Bold Tag in String | Medium | String, Array, Greedy | 2025-12-30 |
| 622 | Design Circular Queue | Medium | Array, Linked List, Design, Queue | 2026-01-24 |
| 636 | Exclusive Time of Functions | Medium | Stack, Parsing | 2025-10-27 |
| 645 | Set Mismatch | Easy | Array, Hash Table, Math | 2026-01-19 |
| 647 | Palindromic Substrings | Medium | String, Two Pointers | 2025-11-24 |
| 648 | Replace Words | Medium | Trie, Hash Set, String Processing | 2025-10-17 |
| 661 | Image Smoother | Easy | Matrix, Array, Simulation | 2025-12-30 |
| 673 | Number of Longest Increasing Subsequence | Medium | Array, Dynamic Programming | 2026-01-09 |
| 681 | Next Closest Time | Medium | String, Simulation, Brute Force | 2025-12-30 |
| 683 | K Empty Slots | Medium | Sliding Window, Two Pointers, Array | 2025-12-30 |
| 684 | Redundant Connection | Medium | Union Find, Dsu, Graph, Cycle Detection, Dfs | 2025-12-29 |
| 685 | Redundant Connection II | Hard | Union Find, Dsu, Graph, Cycle Detection, Directed Graph | 2025-12-30 |
| 686 | Repeated String Match | Medium | String Matching, Kmp, Rabin Karp, Rolling Hash | 2025-12-30 |
| 690 | Employee Importance | Medium | Dfs, Bfs, Hash Table | 2025-12-16 |
| 692 | Top K Frequent Words | Medium | Hash Table, Heap, Sorting, String | 2026-01-08 |
| 695 | Max Area of Island | Medium | Dfs, Graph, Matrix | 2025-10-20 |
| 708 | Insert into a Sorted Circular Linked List | Medium | Linked List, Circular | 2025-10-27 |
| 713 | Subarray Product Less Than K | Medium | Sliding Window, Two Pointers | 2026-03-21 |
| 715 | Range Module | Hard | Design, Data Structures, Interval, Map, Tree Map | 2025-12-31 |
| 717 | 1-bit and 2-bit Characters | Easy | Array, Parsing | 2025-10-29 |
| 721 | Accounts Merge | Medium | Array, Hash Table, String, Union Find, Dfs | 2026-01-11 |
| 729 | My Calendar I | Medium | Array, Binary Search, Design, Ordered Set | 2026-01-17 |
| 732 | My Calendar III | Hard | Array, Binary Search, Design, Segment Tree, Ordered Set | 2026-01-18 |
| 739 | Daily Temperatures | Medium | Array, Stack, Monotonic Stack | 2026-01-29 |
| 743 | Network Delay Time | Medium | Graph, Shortest Path, Dijkstra | 2026-02-03 |
| 752 | Open the Lock | Medium | Bfs, Shortest Path, Lock | 2025-10-20 |
| 772 | Basic Calculator III | Hard | String, Stack, Recursion, Expression Evaluation | 2025-11-13 |
| 787 | Cheapest Flights Within K Stops | Medium | Graph, Shortest Path, Dynamic Programming, Bellman Ford | 2026-02-04 |
| 794 | Valid Tic-Tac-Toe State | Medium | Simulation, Data Structures, Game Logic, Validation, Tic Tac Toe, Game Validation | 2025-09-24 |
| 802 | Find Eventual Safe States | Medium | Graph, Dfs, Cycle Detection | 2026-01-15 |
| 841 | Keys and Rooms | Medium | Graph, Dfs, Bfs | 2026-03-12 |
| 843 | Guess the Word | Hard | Array, String, Interactive, Minmax | 2026-02-02 |
| 844 | Backspace String Compare | Easy | String, Two Pointers, Stack | 2026-01-12 |
| 850 | Rectangle Area II | Hard | Geometry, Sweep Line, Segment Tree | 2025-12-16 |
| 860 | Lemonade Change | Easy | Array, Greedy, Simulation | 2026-01-03 |
| 862 | Shortest Subarray with Sum at Least K | Hard | Array, Sliding Window, Deque, Prefix Sum, Monotonic Deque | 2026-01-26 |
| 863 | All Nodes Distance K in Binary Tree | Medium | Tree, Dfs, Bfs | 2025-10-25 |
| 875 | Koko Eating Bananas | Medium | Array, Binary Search | 2026-02-06 |
| 876 | Middle of the Linked List | Easy | Linked List, Two Pointers | 2026-03-10 |
| 893 | Groups of Special-Equivalent Strings | Easy | String, Hash | 2026-02-15 |
| 894 | All Possible Full Binary Trees | Medium | Tree, Recursion, Memoization | 2026-04-12 |
| 912 | Sort an Array | Medium | Sorting, Merge Sort, Heap Sort, Counting Sort, Data Structures, Divide Conquer | 2025-10-06 |
| 918 | Maximum Sum Circular Subarray | Medium | Dp, Array, Kadane | 2026-03-25 |
| 921 | Minimum Add to Make Parentheses Valid | Medium | String, Stack, Greedy | 2025-11-04 |
| 938 | Range Sum of BST | Easy | Tree, Bst, Dfs | 2025-11-24 |
| 969 | Pancake Sorting | Medium | Array, Sorting | 2025-11-18 |
| 973 | K Closest Points to Origin | Medium | Array, Sorting | 2025-10-21 |
| 974 | Subarray Sums Divisible by K | Medium | Array, Hash Table, Prefix Sum | 2026-02-02 |
| 981 | Time Based Key-Value Store | Medium | Hash Table, Binary Search, Design | 2026-01-30 |
| 983 | Minimum Cost For Tickets | Medium | Dynamic Programming | 2025-11-24 |
| 990 | Satisfiability of Equality Equations | Medium | Data Structures, Disjoint Set, Graph, Dfs, Connected Components, Graph Coloring | 2025-10-04 |
| 993 | Cousins in Binary Tree | Easy | Tree, Bfs, Binary Tree | 2026-01-07 |
| 994 | Rotting Oranges | Medium | Array, Matrix, Bfs | 2025-12-13 |
| 1029 | Two City Scheduling | Medium | Array, Greedy, Sorting | 2026-01-04 |
| 1047 | Remove All Adjacent Duplicates In String | Easy | String, Stack, Two Pointers | 2025-11-24 |
| 1087 | Brace Expansion | Medium | Backtracking, String | 2026-03-26 |
| 1091 | Shortest Path in Binary Matrix | Medium | Graph, Bfs | 2026-03-11 |
| 1094 | Car Pooling | Medium | Array, Sorting | 2025-10-22 |
| 1109 | Corporate Flight Bookings | Medium | Array, Prefix Sum, Difference Array | 2026-02-05 |
| 1115 | Print FooBar Alternately | Medium | Concurrency | 2026-03-28 |
| 1124 | Longest Well-Performing Interval | Medium | Hash Map, Prefix Sum | 2025-10-16 |
| 1136 | Parallel Courses | Hard | Graph, Topological Sort, Dfs, Dynamic Programming | 2026-01-27 |
| 1146 | Snapshot Array | Medium | Design, Binary Search | 2026-03-19 |
| 1177 | Can Make Palindrome from Substring | Medium | String, Bit Manipulation, Prefix Sum, Hash Table | 2026-01-01 |
| 1188 | Design Bounded Blocking Queue | Medium | Concurrency, Design | 2026-03-29 |
| 1197 | Minimum Knight Moves | Medium | Bfs | 2026-03-19 |
| 1202 | Smallest String With Swaps | Medium | String, Graph, Dsu | 2026-03-09 |
| 1206 | Design Skiplist | Hard | Data Structures, Skiplist, Linked List | 2025-12-03 |
| 1207 | Unique Number of Occurrences | Easy | Array, Hash Table | 2025-10-20 |
| 1209 | Remove All Adjacent Duplicates in String II | Medium | String, Stack, Two Pointers | 2025-11-24 |
| 1217 | Minimum Cost to Move Chips to The Same Position | Easy | Array, Math, Greedy | 2026-01-04 |
| 1233 | Remove Sub-Folders from the Filesystem | Medium | Array, String, Trie, Sorting | 2026-01-23 |
| 1242 | Web Crawler Multithreaded | Medium | Multithreading, Concurrency, Data Structures, Synchronization, Web Crawler, Concurrent Programming | 2025-09-24 |
| 1247 | Minimum Swaps to Make Strings Equal | Medium | String, Math, Greedy | 2026-01-04 |
| 1249 | Minimum Remove to Make Valid Parentheses | Medium | String, Stack | 2025-10-22 |
| 1275 | Find Winner on a Tic Tac Toe Game | Easy | Simulation, Matrix | 2026-03-04 |
| 1319 | Number of Operations to Make Network Connected | Medium | Graph, Dsu | 2026-03-10 |
| 1328 | Break a Palindrome | Medium | String, Greedy | 2026-04-07 |
| 1340 | Jump Game V | Hard | Array, Dynamic Programming, Dfs, Memoization | 2026-01-10 |
| 1344 | Angle Between Hands of a Clock | Medium | Math | 2026-03-04 |
| 1353 | Maximum Number of Events That Can Be Attended | Medium | Greedy, Heap | 2026-04-13 |
| 1376 | Time Needed to Inform All Employees | Medium | Tree, Dfs, Bfs | 2026-03-17 |
| 1400 | Construct K Palindrome Strings | Medium | String, Greedy, Hash Table | 2026-01-04 |
| 1424 | Diagonal Traverse II | Medium | Array, Matrix, Hash Map, Bfs | 2025-11-17 |
| 1438 | Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit | Medium | Sliding Window, Monotonic Queue | 2026-02-12 |
| 1443 | Minimum Time to Collect All Apples in a Tree | Medium | Tree, Dfs, Bfs, Graph | 2025-10-20 |
| 1448 | Count Good Nodes in Binary Tree | Medium | Tree, Dfs, Bfs | 2026-03-18 |
| 1488 | Avoid Flood in The City | Medium | Array, Greedy, Binary Search, Set | 2026-02-07 |
| 1570 | Dot Product of Two Sparse Vectors | Medium | Hash Map, Data Structure, Optimization | 2025-10-19 |
| 1584 | Min Cost to Connect All Points | Medium | Graph, Mst, Dsu | 2026-03-08 |
| 1605 | Find Valid Matrix Given Row and Column Sums | Medium | Array, Matrix, Greedy | 2026-01-04 |
| 1624 | Largest Substring Between Two Equal Characters | Easy | String, Hash Table | 2026-01-19 |
| 1650 | Lowest Common Ancestor of a Binary Tree III | Medium | Tree, Binary Tree, Lca | 2025-10-20 |
| 1669 | Merge In Between Linked Lists | Medium | Linked List | 2026-04-15 |
| 1670 | Design Front Middle Back Queue | Medium | Design, Deque, Data Structure | 2026-01-13 |
| 1701 | Average Waiting Time | Medium | Array, Simulation | 2026-01-19 |
| 1710 | Maximum Units on a Truck | Easy | Array, Greedy, Sorting | 2026-01-04 |
| 1762 | Buildings With an Ocean View | Medium | Array, Stack, Monotonic Stack | 2025-11-24 |
| 1768 | Merge Strings Alternately | Easy | String, Two Pointers | 2026-03-27 |
| 1801 | Number of Orders in the Backlog | Medium | Array, Heap, Priority Queue, Simulation | 2026-01-22 |
| 1856 | Maximum Sum of Minimum Product | Medium | Stack, Monotonic Stack, Prefix Sum | 2025-10-17 |
| 1865 | Finding Pairs With a Certain Sum | Medium | Hash Map, Data Structure | 2025-10-19 |
| 1868 | Product of Two Run-Length Encoded Arrays | Medium | Run Length Encoding, Two Pointers, Array Processing | 2025-10-20 |
| 1870 | Minimum Speed to Arrive on Time | Medium | Binary Search | 2026-03-30 |
| 1944 | Number of Visible People in a Queue | Hard | Stack, Monotonic Stack | 2026-02-09 |
| 1976 | Number of Ways to Arrive at Destination | Medium | Dijkstra, Shortest Path, Graph, Dynamic Programming | 2025-12-28 |
| 2043 | Simple Bank System | Medium | Design, Data Structure | 2025-10-20 |
| 2080 | Range Frequency Queries | Medium | Array, Hash Map, Binary Search, Design | 2026-01-28 |
| 2185 | Counting Words With a Given Prefix | Easy | String, Array | 2026-01-19 |
| 2270 | Number of Ways to Split Array | Medium | Prefix Sum, Array | 2026-04-06 |
| 2342 | Max Sum of a Pair With Equal Sum of Digits | Medium | Hash Map, Array | 2026-04-11 |
| 2365 | Task Scheduler II | Medium | Hash Map, Simulation | 2026-04-10 |
| 2406 | Divide Intervals Into Minimum Number of Groups | Medium | Greedy, Heap, Intervals | 2026-03-16 |
| 2433 | Find The Original Array of Prefix Xor | Medium | Bit Manipulation, Prefix | 2026-04-05 |
| 2461 | Maximum Sum of Distinct Subarrays With Length K | Medium | Sliding Window, Hash Map | 2026-04-09 |
| 2466 | Count Ways To Build Good Strings | Medium | Dynamic Programming, Dp | 2025-10-16 |
| 2799 | Count Complete Subarrays in an Array | Medium | Sliding Window, Hash Map | 2025-10-17 |
| 3110 | Score of a String | Easy | String, Array | 2026-01-18 |
| 3112 | Minimum Time to Visit Disappearing Nodes | Medium | Graph, Shortest Path, Dijkstra | 2026-02-08 |
| 3341 | Find Minimum Time to Reach Last Room I | Medium | Graph, Shortest Path, Dijkstra, Grid | 2026-02-10 |
| 3342 | Find Minimum Time to Reach Last Room II | Medium | Graph, Shortest Path, Dijkstra, Grid | 2026-02-10 |
| 3439 | Reschedule Meetings for Maximum Free Time I | Medium | Array, Intervals, Sliding Window, Prefix Sum | 2026-02-06 |
| 3477 | Number of Unplaced Fruits | Medium | Array, Greedy, Segment Tree | 2026-01-16 |
| lcr113 | LCR 113. Course Schedule II | Medium | Graph, Topological Sort, Dfs | 2026-01-14 |