The number of leetcode questions is increasing every week.
I will constantly seek and summarize better solutions to the problem and keep updating.
- Array
- Bit Binary Search Manipulation
- String
- Linked List
- Stack
- Queue
- Heap
- Tree
- Hash Table
- Math
- Two Pointers
- Sort
- Recursion
- Binary Search
- Binary Search Tree
- Breadth-First Search
- Depth-First Search
- Backtracking
- Dynamic Programming
- Greedy
- Graph
- Geometry
- Simulation
- Design
- Divide and Conquer
| # | Title | Solution | Time | Space | Difficulty |
|---|---|---|---|---|---|
| 002 | Add Two Numbers | Python | O(n) | O(n) | Medium |
| 021 | Merge Two Sorted Lists | Python | O(n+m) | O(1) | Easy |
| 023 | Merge k Sorted Lists | Python | O(nlogk) | O(1) | Hard |
| 024 | Swap Nodes in Pairs | Python | Easy | ||
| 025 | Reverse Nodes in k-Group | Python | Hard | ||
| 061 | Rotate List | Python | O(n) | O(1) | Medium |
| 082 | Remove Duplicates from Sorted List II | Python | O(n) | O(1) | Medium |
| 083 | Remove Duplicates from Sorted List | Python | O(n) | O(1) | Easy |
| 092 | Reverse Linked List II | Python | Medium | ||
| 138 | Copy List with Random Pointer | Python | O(n) | O(1) | Medium |
| 160 | Intersection of Two Linked Lists | Python | O(n) | O(1) | Easy |
| 203 | Remove Linked List Elements | Python | O(n) | O(1) | Easy |
| 206 | Reverse Linked List | Python | O(n) | O(1) | Easy |
| 234 | Palindrome Linked List | Python | O(n) | O(1) | Easy |
| 237 | Delete Node in a Linked List | Python | O(1) | O(1) | Easy |
| 328 | Odd Even Linked List | Python | O(n) | O(1) | Medium |
| 369 | Plus One Linked List | Python | Medium | ||
| 430 | Flatten a Multilevel Doubly Linked List | Python | O(n) | O(1) | Meduim |
| 445 | Add Two Numbers II | Python | Medium | ||
| 725 | Split Linked List in Parts | Python | Medium | ||
| 817 | Linked List Components | Python | Medium |
| # | Title | Solution | Time | Space | Difficulty |
|---|---|---|---|---|---|
| 239 | Sliding Window Maximum | Python | O(n) | O(1) | Hard |
| 281 | Zigzag Iterator | Python | Medium | ||
| 346 | Moving Average from Data Stream | Python | Easy | ||
| 862 | Shortest Subarray with Sum at Least K | Python | Hard |
| # | Title | Solution | Time | Space | Difficulty |
|---|---|---|---|---|---|
| 264 | Ugly Number II | Python | Medium | ||
| 295 | Find Median from Data Stream | Python | Hard | ||
| 313 | Super Ugly Number | Python | Medium | ||
| 358 | Rearrange String k Distance Apart | Python | Hard | ||
| 373 | Find K Pairs with Smallest Sums | Python | Medium | ||
| 378 | Kth Smallest Element in a Sorted Matrix | Python | Medium | ||
| 407 | Trapping Rain Water II | Python | Hard | ||
| 632 | Smallest Range | Python | Hard | ||
| 846 | Hand of Straights | Python | Medium | ||
| 855 | Exam Room | Python | Medium | ||
| 857 | Minimum Cost to Hire K Workers | Python | Hard | ||
| 871 | Minimum Number of Refueling Stops | Python | Hard |
| # | Title | Solution | Time | Space | Difficulty |
|---|---|---|---|---|---|
| 056 | Merge Intervals | Python | O(n) | O(1) | Medium |
| 057 | Insert Interval | Python | Hard | ||
| 075 | Sort Colors | Python | O(n) | O(1) | Medium |
| 088 | Merge Sorted Array | Python | O(n) | O(1) | Easy |
| 147 | Insertion Sort List | Python | Medium | ||
| 148 | Sort List | Python | Medium | ||
| 164 | Maximum Gap | Python | Hard | ||
| 179 | Largest Number | Python | O(nlogn) | O(1) | Medium |
| 218 | The Skyline Problem | Python | Hard | ||
| 242 | Valid Anagram | Python | O(n) | O(1) | Easy |
| 252 | Meeting Rooms | Python | Easy | ||
| 253 | Meeting Rooms II | Python | Medium | ||
| 274 | H-Index | Python | Medium | ||
| 280 | Wiggle Sort | Python | Medium | ||
| 324 | Wiggle Sort II | Python | Medium | ||
| 347 | Top K Frequent Elements | Python | Medium | ||
| 406 | Queue Reconstruction by Height | Python | Medium | ||
| 451 | Sort Characters By Frequency | Python | O(nlogn) | 1 | Medium |
| 692 | Top K Frequent Words | Python | Medium |
| # | Title | Solution | Time | Space | Difficulty |
|---|---|---|---|---|---|
| 019 | Remove Nth Node From End of List | Python | O(n) | O(1) | Easy |
| 028 | Implement strStr() | Python | O(n) | O(1) | Easy |
| 035 | Search Insert Position | Python | O(1) | Easy | |
| 086 | Partition List | Python | Medium | ||
| 125 | Valid Palindrome | Python | O(n) | O(1) | Easy |
| 141 | Linked List Cycle | Python | O(n) | O(1) | Easy |
| 142 | Linked List Cycle II | Python | Medium | ||
| 143 | Reorder List | Python | Medium | ||
| 167 | Two Sum II - Input array is sorted | Python | O(n) | O(n) | Easy |
| 259 | 3Sum Smaller | Python | Medium | ||
| 283 | Move Zeroes | Python | O(n) | O(1) | Easy |
| 287 | Find the Duplicate Number | Python | Hard | ||
| 344 | Reverse String | Python | O(n) | O(1) | Easy |
| 345 | Reverse Vowels of a String | Python | O(n) | O(1) | Easy |
| 350 | Intersection of Two Arrays II | Python | O(n) | O(1) | Easy |
| 360 | Sort Transformed Array | Python | Medium | ||
| 457 | Circular Array Loop | Python | Medium | ||
| 567 | Permutation in String | Python | Medium | ||
| 611 | Valid Triangle Number | Python | Medium | ||
| 777 | Swap Adjacent in LR String | Python | Medium | ||
| 826 | Most Profit Assigning Work | Python | Medium | ||
| 828 | Unique Letter String | Python | Hard | ||
| 844 | Backspace String Compare | Python | Easy | ||
| 876 | Middle of the Linked List | Python | Easy |
| # | Title | Solution | Time | Space | Difficulty |
|---|---|---|---|---|---|
| 220 | Contains Duplicate III | Python | O(1) | Medium | |
| 230 | Kth Smallest Element in a BST | Python | O(logn) | O(n) | Medium |
| 235 | Lowest Common Ancestor of a Binary Search Tree | Python | O(n) | O(1) | Easy |
| 270 | Closest Binary Search Tree Value | Python | Easy | ||
| 285 | Inorder Successor in BST | Python | Medium | ||
| 352 | Data Stream as Disjoint Intervals | Python | Hard | ||
| 449 | Serialize and Deserialize BST | Python | Medium | ||
| 450 | Delete Node in a BST | Python | Medium | ||
| 530 | Minimum Absolute Difference in BST | Python | Easy | ||
| 776 | Split BST | Python | Medium | ||
| 783 | Minimum Distance Between BST Nodes | Python | Easy |
| # | Title | Solution | Time | Space | Difficulty |
|---|---|---|---|---|---|
| 765 | Couples Holding Hands | Python | Hard |
| # | Title | Solution | Time | Space | Difficulty |
|---|---|---|---|---|---|
| 587 | Erect the Fence | Python | Hard |
| # | Title | Solution | Time | Space | Difficulty |
|---|---|---|---|---|---|
| 874 | Walking Robot Simulation | Python | Easy |
| # | Title | Solution | Time | Space | Difficulty |
|---|---|---|---|---|---|
| 146 | LRU Cache | Python | Hard | ||
| 155 | Min Stack | Python | ---- | ---- | Easy |
| 225 | Implement Stack using Queues | Python | _ | _ | Easy |
| 284 | Peeking Iterator | Python | Medium | ||
| 348 | Design Tic-Tac-Toe | Python | Medium | ||
| 353 | Design Snake Game | Python | Medium | ||
| 355 | Design Twitter | Python | Medium | ||
| 359 | Logger Rate Limiter | Python | Easy | ||
| 362 | Design Hit Counter | Python | Medium | ||
| 379 | Design Phone Directory | Python | Medium | ||
| 380 | Insert Delete GetRandom O(1) | Python | Hard | ||
| 381 | Insert Delete GetRandom O(1) - Duplicates allowed | Python | Hard | ||
| 384 | Shuffle an Array | Python | O(n) | O(1) | Medium |
| 432 | All O`one Data Structure | Python | Hard | ||
| 460 | LFU Cache | Python | Hard | ||
| 535 | Encode and Decode TinyURL | Python | Medium | ||
| 588 | Design In-Memory File System | Python | Hard | ||
| 604 | Design Compressed String Iterator | Python | Easy | ||
| 622 | Design Circular Queue | Python | Medium | ||
| 631 | Design Excel Sum Formula | Python | Hard | ||
| 635 | Design Log Storage System | Python | Medium | ||
| 642 | Design Search Autocomplete System | Python | Hard | ||
| 707 | Design Linked List | Python | - | - | Easy |
| 715 | Range Module | Python | Hard | ||
| 716 | Max Stack | Python | Easy | ||
| 745 | Prefix and Suffix Search | Python | Hard |
| # | Title | Solution | Time | Space | Difficulty |
|---|---|---|---|---|---|
| 169 | Majority Element | Python | O(1) | Easy |
| # | Title | Solution | Difficulty |
|---|---|---|---|
| 175 | Combine Two Tables | MySQL | Easy |
| 176 | Second Highest Salary | MySQL | Easy |
| 177 | Nth Highest Salary | MySQL | Medium |
| 178 | Rank Scores | MySQL | Medium |
| 180 | Consecutive Numbers | MySQL | Medium |
| 181 | Employees Earning More Than Their Managers | MySQL | Easy |
| 182 | Duplicate Emails | MySQL | Easy |
| 183 | Customers Who Never Order | MySQL | Easy |
| 184 | Department Highest Salary | MySQL | Medium |
| 185 | Department Top Three Salaries | MySQL | Hard |
| 196 | Delete Duplicate Emails | MySQL | Easy |
| 197 | Rising Temperature | MySQL | Easy |
| 262 | Trips and Users | MySQL | Hard |
| 595 | Big Countries | MySQL | Easy |
| 620 | Not Boring Movies | MySQL | Easy |
| 627 | Swap Salary | MySQL | Easy |
| # | Title | Solution | Difficulty |
|---|---|---|---|
| 192 | Word Frequency | Shell | Medium |
| 193 | Valid Phone Numbers | Shell | Easy |
| 194 | Transpose File | Shell | Medium |
| 195 | Tenth Line | Shell | Easy |