- R.I.P. to my old Leetcode repository, where there were
5.7k+stars and2.2k+forks (ever the top 3 in the field). - Since free questions may be even mistakenly taken down by some companies, only solutions will be post on now.
- There are new LeetCode questions every week. I'll keep updating for full summary and better solutions.
- For more problem solutions, you can see my LintCode, GoogleKickStart repositories.
- For more challenging problem solutions, you can also see my GoogleCodeJam, FacebookHackerCup repositories.
- Hope you enjoy the journey of learning data structures and algorithms.
- Notes: "🔒" means your subscription of LeetCode premium membership is required for reading the question.
- Bit Manipulation
- Array
- String
- Linked List
- Stack
- Queue
- Binary Heap
- Tree
- Hash Table
- Math
- Sort
- Two Pointers
- Recursion
- Binary Search
- Binary Search Tree
- Breadth-First Search
- Depth-First Search
- Backtracking
- Dynamic Programming
- Greedy
- Graph
- Geometry
- Simulation
- Design
- Concurrency
- C++
- Python
- Algorithms
- Math
- Visualization
- Handy Table
- Thinking Techniques as follows:
| n | Complexity | Possible Algorithms & Techniques |
|---|---|---|
| 1018+ | O(1) | Math |
| 1018 | O(logn) | Binary & Ternary Search / Matrix Power / Cycle Tricks / Big Simulation Steps / Values Reranking / Math |
| 1016 | O(n1/2) | Math |
| 108 | O(n) | Greedy / Ad-hoc / DP |
| 4×107 | O(nlogn) | Linear # Calls to Binary & Ternary Search / Pre-processing & Querying / Divide and Conquer |
| 104 | O(n2) | Ad-hoc / DP / Greedy / Divide and Conquer / Branch and Bound |
| 500 | O(n3) | Ad-hoc / DP / Greedy / Divide and Conquer / Branch and Bound |
| 90 | O(n4) | Ad-hoc / DP / Greedy / Divide and Conquer / Branch and Bound |
| 50 | O(n5) | Branch and Bound |
| 40 | O(nx2n/2) | Meet in the Middle |
| 20 | O(n×2n) | Backtracking / Generating 2n Subsets / Bitmask Technique |
| 11 | O(n!) | Factorial / Permutation / Combination Algorithm |
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 0239 | Sliding Window Maximum | C++ Python | O(n) | O(k) | Hard | EPI, LintCode | Mono Deque |
| 0281 | Zigzag Iterator | C++ Python | O(n) | O(k) | Medium | 🔒 | |
| 0346 | Moving Average from Data Stream | C++ Python | O(1) | O(w) | Easy | 🔒 | |
| 0933 | Number of Recent Calls | C++ Python | O(1) on average | O(w) | Easy | ||
| 1424 | Diagonal Traverse II | C++ Python | O(m * n) | O(m) | Medium | ||
| 1438 | Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit | C++ Python | O(n) | O(n) | Hard | Mono Deque | |
| 1499 | Max Value of Equation | C++ Python | O(n) | O(n) | Hard | Mono Deque | |
| 1696 | Jump Game VI | C++ Python | O(n) | O(k) | Medium | Mono Deque, Sliding Window |
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 0264 | Ugly Number II | C++ Python | O(n) | O(1) | Medium | CTCI, LintCode | BST, Heap |
| 0295 | Find Median from Data Stream | C++ Python | O(nlogn) | O(n) | Hard | EPI, LintCode | BST, Heap |
| 0313 | Super Ugly Number | C++ Python | O(n * k) | O(n + k) | Medium | BST, Heap | |
| 0358 | Rearrange String k Distance Apart | C++ Python | O(n) | O(n) | Hard | 🔒 | Greedy, Heap |
| 0373 | Find K Pairs with Smallest Sums | C++ Python | O(k * log(min(n, m, k))) | O(min(n, m, k)) | Medium | ||
| 0378 | Kth Smallest Element in a Sorted Matrix | C++ Python | O(k * log(min(n, m, k))) | O(min(n, m, k)) | Medium | LintCode | |
| 0407 | Trapping Rain Water II | C++ Python | O(m * n * (logm + logn)) | O(m * n) | Hard | LintCode | |
| 0480 | Sliding Window Median | C++ Python | O(nlogk) | O(k) | Hard | BST, Heap | |
| 0502 | IPO | C++ Python | O(nlogn) | O(n) | Hard | Heap | |
| 0632 | Smallest Range | C++ Python | O(nlogk) | O(k) | Hard | ||
| 0703 | Kth Largest Element in a Stream | C++ Python | O(nlogk) | O(k) | Easy | ||
| 0846 | Hand of Straights | C++ Python | O(nlogn) | O(n) | Medium | ||
| 0855 | Exam Room | C++ Python | seat: O(logn) leave: O(logn) |
O(n) | Medium | BST, Hash | |
| 0857 | Minimum Cost to Hire K Workers | C++ Python | O(nlogn) | O(n) | Hard | Sort | |
| 0871 | Minimum Number of Refueling Stops | C++ Python | O(nlogn) | O(n) | Hard | Sort | |
| 1046 | Last Stone Weight | C++ Python | O(nlogn) | O(n) | Easy | ||
| 1057 | Campus Bikes | C++ Python | O((w * b) * log(w * b)) | O(w * b) | Medium | 🔒 | |
| 1383 | Maximum Performance of a Team | C++ Python | O(nlogn) | O(n) | Hard | variant of Minimum Cost to Hire K Workers | Sort |
| 1439 | Find the Kth Smallest Sum of a Matrix With Sorted Rows | C++ Python | O(m * klogk) | O(k) | Hard | Binary Search | |
| 1606 | Find Servers That Handled Most Number of Requests | C++ Python | O(nlogk) | O(k) | Hard | SortedList | |
| 1642 | Furthest Building You Can Reach | C++ Python | O(nlogk) | O(k) | Medium | ||
| 1675 | Minimize Deviation in Array | C++ Python | O((n * log(max_num)) * logn) | O(n) | Hard | ||
| 1792 | Maximum Average Pass Ratio | C++ Python | O(n + mlogn) | O(n) | Medium | ||
| 1882 | Process Tasks Using Servers | C++ Python | O(n + mlogn) | O(n) | Medium | ||
| 1962 | Remove Stones to Minimize the Total | C++ Python | O(klogn) | O(1) | Medium |
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 0056 | Merge Intervals | C++ Python | O(nlogn) | O(1) | Hard | ||
| 0057 | Insert Interval | C++ Python | O(n) | O(1) | Hard | ||
| 0075 | Sort Colors | C++ Python | O(n) | O(1) | Medium | Tri Partition | |
| 0088 | Merge Sorted Array | C++ Python | O(n) | O(1) | Easy | ||
| 0147 | Insertion Sort List | C++ Python | O(n^2) | O(1) | Medium | ||
| 0148 | Sort List | C++ Python | O(nlogn) | O(logn) | Medium | ||
| 0164 | Maximum Gap | C++ Python | O(n) | O(n) | Hard | Tricky | |
| 0179 | Largest Number | C++ Python | O(nlogn) | O(1) | Medium | ||
| 0218 | The Skyline Problem | C++ Python | O(nlogn) | O(n) | Hard | Sort, BST | |
| 0252 | Meeting Rooms | C++ Python | O(nlogn) | O(n) | Easy | 🔒 | |
| 0253 | Meeting Rooms II | C++ Python | O(nlogn) | O(n) | Medium | 🔒 | |
| 0274 | H-Index | C++ Python | O(n) | O(n) | Medium | Counting Sort | |
| 0280 | Wiggle Sort | C++ Python | O(n) | O(1) | Medium | 🔒 | |
| 0324 | Wiggle Sort II | C++ Python | O(n) on average | O(1) | Medium | variant of Sort Colors | Quick Select, Tri Partition |
| 0347 | Top K Frequent Elements | C++ Python | O(n) | O(n) | Medium | Quick Select, Heap, Bucket Sort | |
| 0406 | Queue Reconstruction by Height | C++ Python | O(n * sqrt(n)) | O(n) | Medium | Tricky | |
| 0451 | Sort Characters By Frequency | C++ Python | O(n) | O(n) | Medium | ||
| 0493 | Reverse Pairs | C++ Python | O(nlogn) | O(n) | Hard | Sort | |
| 0692 | Top K Frequent Words | C++ Python | O(n + klogk) on average | O(n) | Medium | Quick Select, Heap, Bucket Sort | |
| 0912 | Sort an Array | C++ Python | O(nlogn) | O(n) | Medium | Merge Sort, Quick Sort | |
| 0937 | Reorder Log Files | C++ Python | O(nlogn * l) | O(l) | Easy | ||
| 0969 | Pancake Sorting | C++ Python | O(nlogn) | O(n) | Medium | variant of Count of Smaller Numbers After Self | BIT, Fenwick Tree, Merge Sort |
| 0973 | K Closest Points to Origin | C++ Python | O(n) on average | O(1) | Easy | Quick Select, Heap | |
| 0976 | Largest Perimeter Triangle | C++ Python | O(nlogn) | O(1) | Easy | ||
| 1054 | Distant Barcodes | C++ Python | O(klogk) | O(k) | Medium | variant of Rearrange String k Distance Apart | |
| 1086 | High Five | C++ Python | O(nlogn) | O(n) | Easy | 🔒 | |
| 1094 | Car Pooling | C++ Python | O(nlogn) | O(n) | Medium | variant of Meeting Rooms II | |
| 1122 | Relative Sort Array | C++ Python | O(nlogn) | O(n) | Easy | ||
| 1229 | Meeting Scheduler | C++ Python | O(nlogn) | O(n) | Medium | Line Sweep, Heap | |
| 1356 | Sort Integers by The Number of 1 Bits | C++ Python | O(nlogn) | O(1) | Easy | Bit Manipulation | |
| 1365 | How Many Numbers Are Smaller Than the Current Number | C++ Python | O(n + m) | O(m) | Easy | Counting Sort | |
| 1366 | Rank Teams by Votes | C++ Python | O(m * (n + mlogm)) | O(m^2) | Medium | ||
| 1451 | Rearrange Words in a Sentence | C++ Python | O(nlogn) | O(n) | Medium | String | |
| 1481 | Least Number of Unique Integers after K Removals | C++ Python | O(n) | O(n) | Medium | Counting Sort | |
| 1509 | Minimum Difference Between Largest and Smallest Value in Three Moves | C++ Python | O(n + klogk) | O(1) | Medium | Quick Select | |
| 1523 | Count Odd Numbers in an Interval Range | C++ Python | O(1) | O(1) | Easy | ||
| 1561 | Maximum Number of Coins You Can Get | C++ Python | O(nlogn) | O(1) | Medium | ||
| 1588 | Sum of All Odd Length Subarrays | C++ Python | O(n) | O(1) | Easy | ||
| 1608 | Special Array With X Elements Greater Than or Equal X | C++ Python | O(n) | O(1) | Easy | variant of H-Index | Counting Sort, Binary Search |
| 1620 | Coordinate With Maximum Network Quality | C++ Python | O(n^2) | O(1) | Medium | ||
| 1621 | Number of Sets of K Non-Overlapping Line Segments | C++ Python | O(1) | O(n) | Medium | Binomial Coefficients, Euler's Theorem |
|
| 1630 | Arithmetic Subarrays | C++ Python | O(n * q) | O(n) | Medium | Arithmetic Series | |
| 1636 | Sort Array by Increasing Frequency | C++ Python | O(nlogn) | O(n) | Easy | ||
| 1637 | Widest Vertical Area Between Two Points Containing No Points | C++ Python | O(nlogn) | O(n) | Medium | ||
| 1680 | Concatenation of Consecutive Binary Numbers | C++ Python | O(n) | O(1) | Medium | ||
| 1685 | Sum of Absolute Differences in a Sorted Array | C++ Python | O(n) | O(1) | Medium | ||
| 1688 | Count of Matches in Tournament | C++ Python | O(1) | O(1) | Easy | ||
| 1703 | Minimum Adjacent Swaps for K Consecutive Ones | C++ Python | O(n) | O(n) | Hard | Prefix Sum | |
| 1716 | Calculate Money in Leetcode Bank | C++ Python | O(1) | O(1) | Easy | Arithmetic Sequence | |
| 1772 | Sort Features by Popularity | C++ Python | O(n) | O(1) | Medium | 🔒 | |
| 1847 | Closest Room | C++ Python | O(nlogn + klogk + klogn) | O(n + k) | Hard | Sort, Binary Search | |
| 1851 | Minimum Interval to Include Each Query | C++ Python | O(nlogn + klogk + klogn) | O(n + k) | Hard | Sort, Heap, Line Sweep | |
| 1859 | Sorting the Sentence | C++ Python | O(n) | O(n) | Easy | Sort, String | |
| 1942 | The Number of the Smallest Unoccupied Chair | C++ Python | O(nlogn) | O(n) | Medium | Line Sweep, Heap | |
| 1943 | Describe the Painting | C++ Python | O(nlogn) | O(n) | Medium | Line Sweep | |
| 1968 | Array With Elements Not Equal to Average of Neighbors | C++ Python | O(n) on average | O(1) | Medium | variant of Wiggle Sort II | Quick Select, Tri Partition |
| 1985 | Find the Kth Largest Integer in the Array | C++ Python | O(n) on average | O(n) | Medium | Quick Select | |
| 1996 | The Number of Weak Characters in the Game | C++ Python | O(nlogn) | O(1) | Medium |
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 0015 | 3 Sum | C++ Python | O(n^2) | O(1) | Medium | Two Pointers | |
| 0016 | 3 Sum Closest | C++ Python | O(n^2) | O(1) | Medium | Two Pointers | |
| 0018 | 4 Sum | C++ Python | O(n^3) | O(1) | Medium | Two Pointers | |
| 0019 | Remove Nth Node From End of List | C++ Python | O(n) | O(1) | Medium | ||
| 0086 | Partition List | C++ Python | O(n) | O(1) | Medium | ||
| 0141 | Linked List Cycle | C++ Python | O(n) | O(1) | Easy | ||
| 0142 | Linked List Cycle II | C++ Python | O(n) | O(1) | Medium | ||
| 0143 | Reorder List | C++ Python | O(n) | O(1) | Medium | ||
| 0167 | Two Sum II - Input array is sorted | C++ Python | O(n) | O(1) | Medium | ||
| 0209 | Minimum Size Subarray Sum | C++ Python | O(n) | O(1) | Medium | Binary Search, Sliding Window | |
| 0259 | 3Sum Smaller | C++ Python | O(n^2) | O(1) | Medium | 🔒, LintCode | |
| 0283 | Move Zeroes | C++ Python | O(n) | O(1) | Easy | ||
| 0287 | Find the Duplicate Number | C++ Python | O(n) | O(1) | Hard | Binary Search, Two Pointers | |
| 0344 | Reverse String | C++ Python | O(n) | O(1) | Easy | ||
| 0345 | Reverse Vowels of a String | C++ Python | O(n) | O(1) | Easy | ||
| 0349 | Intersection of Two Arrays | C++ Python | O(m + n) | O(min(m, n)) | Easy | EPI | Hash, Binary Search |
| 0350 | Intersection of Two Arrays II | C++ Python | O(m + n) | O(1) | Easy | EPI | Hash, Binary Search |
| 0360 | Sort Transformed Array | C++ Python | O(n) | O(1) | Medium | 🔒 | |
| 0424 | Longest Repeating Character Replacement | C++ Python | O(n) | O(1) | Medium | Sliding Window | |
| 0457 | Circular Array Loop | C++ Python | O(n) | O(1) | Medium | ||
| 0567 | Permutation in String | C++ Python | O(n) | O(1) | Medium | ||
| 0611 | Valid Triangle Number | C++ Python | O(n^2) | O(1) | Medium | ||
| 0777 | Swap Adjacent in LR String | C++ Python | O(n) | O(1) | Medium | ||
| 0826 | Most Profit Assigning Work | C++ Python | O(mlogm + nlogn) | O(n) | Medium | ||
| 0828 | Count Unique Characters of All Substrings of a Given String | C++ Python | O(n) | O(1) | Hard | ||
| 0844 | Backspace String Compare | C++ Python | O(m + n) | O(1) | Easy | ||
| 0862 | Shortest Subarray with Sum at Least K | C++ Python | O(n) | O(n) | Hard | Mono Deque, Sliding Window | |
| 0876 | Middle of the Linked List | C++ Python | O(n) | O(1) | Easy | ||
| 0904 | Fruit Into Baskets | C++ Python | O(n) | O(1) | Medium | Sliding Window | |
| 0930 | Binary Subarrays With Sum | C++ Python | O(n) | O(1) | Medium | Sliding Window | |
| 0977 | Squares of a Sorted Array | C++ Python | O(n) | O(1) | Easy | ||
| 0992 | Subarrays with K Different Integers | C++ Python | O(n) | O(k) | Hard | Two Pointers, Sliding Window | |
| 1004 | Max Consecutive Ones III | C++ Python | O(n) | O(1) | Medium | Sliding Window | |
| 1033 | Moving Stones Until Consecutive | C++ Python | O(1) | O(1) | Easy | ||
| 1040 | Moving Stones Until Consecutive II | C++ Python | O(nlogn) | O(1) | Medium | ||
| 1151 | Minimum Swaps to Group All 1's Together | C++ Python | O(n) | O(1) | Medium | 🔒 | Sliding Window |
| 1156 | Swap For Longest Repeated Character Substring | C++ Python | O(n) | O(1) | Medium | Sliding Window | |
| 1176 | Diet Plan Performance | C++ Python | O(n) | O(1) | Easy | Sliding Window | |
| 1208 | Get Equal Substrings Within Budget | C++ Python | O(n) | O(1) | Medium | Sliding Window | |
| 1213 | Intersection of Three Sorted Arrays | C++ Python | O(n) | O(1) | Easy | 🔒 | |
| 1169 | Invalid Transactions | C++ Python | O(nlogn) | O(n) | Medium | Sliding Window, Line Sweep | |
| 1214 | Two Sum BSTs | C++ Python | O(n) | O(n) | Medium | 🔒 | Stack |
| 1234 | Replace the Substring for Balanced String | C++ Python | O(n) | O(t) | Medium | Two Pointers, Sliding Window | |
| 1248 | Count Number of Nice Subarrays | C++ Python | O(n) | O(k) | Medium | variant of Subarrays with K Different Integers | Two Pointers, Sliding Window |
| 1297 | Maximum Number of Occurrences of a Substring | C++ Python | O(n) | O(n) | Medium | Sliding Window, Rabin-Karp Algorithm |
|
| 1305 | All Elements in Two Binary Search Trees | C++ Python | O(n) | O(h) | Medium | Stack | |
| 1316 | Distinct Echo Substrings | C++ Python | O(n^2 + d) | O(r) | Hard | KMP Algorithm, Sliding Window, Rabin-Karp Algorithm |
|
| 1358 | Number of Substrings Containing All Three Characters | C++ Python | O(n) | O(1) | Medium | Sliding Window | |
| 1423 | Maximum Points You Can Obtain from Cards | C++ Python | O(n) | O(1) | Medium | Sliding Window | |
| 1425 | Constrained Subset Sum | C++ Python | O(n) | O(k) | Hard | variant of Sliding Window Maximum | Mono Deque, Sliding Window |
| 1456 | Maximum Number of Vowels in a Substring of Given Length | C++ Python | O(n) | O(1) | Medium | Sliding Window | |
| 1493 | Longest Subarray of 1's After Deleting One Element | C++ Python | O(n) | O(1) | Medium | Sliding Window | |
| 1498 | Number of Subsequences That Satisfy the Given Sum Condition | C++ Python | O(nlogn) | O(n) | Medium | Two Pointers | |
| 1508 | Range Sum of Sorted Subarray Sums | C++ Python | O(nlog(sum(nums))) | O(n) | Medium | Binary Search, Two Pointers, Sliding Window | |
| 1521 | Find a Value of a Mysterious Function Closest to Target | C++ Python | O(nlogm) | O(logm) | Hard | DP, Two Pointers, Sliding Window | |
| 1604 | Alert Using Same Key-Card Three or More Times in a One Hour Period | C++ Python | O(nlogn) | O(n) | Medium | Two Pointers, Sliding Window | |
| 1658 | Minimum Operations to Reduce X to Zero | C++ Python | O(n) | O(1) | Medium | Two Pointers | |
| 1687 | Delivering Boxes from Storage to Ports | C++ Python | O(nlogn) | O(n) | Hard | Two Pointers, Sliding Window | |
| 1695 | Maximum Erasure Value | C++ Python | O(n) | O(n) | Medium | Two Pointers, Sliding Window | |
| 1712 | Ways to Split Array Into Three Subarrays | C++ Python | O(n) | O(n) | Medium | Two Pointers, Prefix Sum | |
| 1750 | Minimum Length of String After Deleting Similar Ends | C++ Python | O(n) | O(1) | Medium | Two Pointers | |
| 1838 | Frequency of the Most Frequent Element | C++ Python | O(nlogn) | O(n) | Medium | Two Pointers, Sliding Window | |
| 1852 | Distinct Numbers in Each Subarray | C++ Python | O(n) | O(k) | Medium | 🔒 | Two Pointers, Sliding Window |
| 1855 | Maximum Distance Between a Pair of Values | C++ Python | O(n + m) | O(1) | Medium | Two Pointers | |
| 1868 | Product of Two Run-Length Encoded Arrays | C++ Python | O(m + n) | O(1) | Medium | 🔒 | Two Pointers |
| 1885 | Count Pairs in Two Arrays | C++ Python | O(nlogn) | O(1) | Medium | 🔒 | Two Pointers |
| 1888 | Minimum Number of Flips to Make the Binary String Alternatings | C++ Python | O(n) | O(1) | Medium | Two Pointers, Sliding Window | |
| 1984 | Minimum Difference Between Highest and Lowest of K Scores | C++ Python | O(nlogn) | O(1) | Easy | Two Pointers, Sliding Window | |
| 1989 | Maximum Number of People That Can Be Caught in Tag | C++ Python | O(n) | O(1) | Medium | 🔒 | Greedy, Two Pointers, Sliding Window |
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 0102 | Binary Tree Level Order Traversal | C++ Python | O(n) | O(n) | Easy | ||
| 0107 | Binary Tree Level Order Traversal II | C++ Python | O(n) | O(n) | Easy | ||
| 0103 | Binary Tree Zigzag Level Order Traversal | Python | O(n) | O(n) | Medium | ||
| 0117 | Populating Next Right Pointers in Each Node II | Python | O(n) | O(1) | Hard | ||
| 0127 | Word Ladder | C++ Python | O(b^(d/2)) | O(w * l) | Medium | CTCI | Bi-BFS |
| 0130 | Surrounded Regions | C++ Python | O(m * n) | O(m + n) | Medium | ||
| 0133 | Clone Graph | Python | O(n) | O(n) | Medium | ||
| 0207 | Course Schedule | C++ Python | O(|V| + |E|) | O(|E|) | Medium | Topological Sort | |
| 0210 | Course Schedule II | C++ Python | O(|V| + |E|) | O(|E|) | Medium | Topological Sort | |
| 0261 | Graph Valid Tree | C++ Python | O(|V| + |E|) | O(|V| + |E|) | Medium | 🔒 | |
| 0269 | Alien Dictionary | C++ Python | O(n) | O(1) | Hard | 🔒 | Topological Sort, BFS, DFS |
| 0286 | Walls and Gates | C++ Python | O(m * n) | O(g) | Medium | 🔒 | |
| 0310 | Minimum Height Trees | C++ Python | O(n) | O(n) | Medium | ||
| 0317 | Shortest Distance from All Buildings | C++ Python | O(k * m * n) | O(m * n) | Hard | 🔒 | |
| 0433 | Minimum Genetic Mutation | C++ Python | O(n * b) | O(b) | Medium | ||
| 0444 | Sequence Reconstruction | C++ Python | O(n * s) | O(n) | Medium | 🔒 | Topological Sort |
| 0490 | The Maze | C++ Python | O(max(r, c) * w) | O(w) | Medium | ||
| 0499 | The Maze III | C++ Python | O(max(r, c) * wlogw) | O(w^2) | Hard | ||
| 0505 | The Maze II | C++ Python | O(max(r, c) * wlogw) | O(w) | Medium | ||
| 0542 | 01 Matrix | C++ Python | O(m * n) | O(1) | Medium | DP | |
| 0666 | Path Sum IV | C++ Python | O(n) | O(w) | Medium | 🔒 | Topological Sort |
| 0675 | Cut Off Trees for Golf Event | C++ Python | O(t * m * n) | O(m * n) | Hard | A* Search Algorithm |
|
| 0742 | Closest Leaf in a Binary Tree | C++ Python | O(n) | O(n) | Medium | ||
| 0743 | Network Delay Time | C++ Python | O(|E| * log|V|) | O(|E|) | Medium | Dijkstra's Algorithm |
|
| 0752 | Open the Lock | C++ Python | O(k * n^k + d) | O(k * n^k + d) | Medium | ||
| 0773 | Sliding Puzzle | C++ Python | O((m * n) * (m * n)!) | O((m * n) * (m * n)!) | Hard | A* Search Algorithm |
|
| 0787 | Cheapest Flights Within K Stops | C++ Python | O(|E| * log|V|) | O(|E|) | Medium | Dijkstra's Algorithm |
|
| 0815 | Bus Routes | C++ Python | O(|E| + |V|) | O(|E| + |V|) | Hard | ||
| 0854 | K-Similar Strings | C++ Python | O(n * n!/(c_a!*...*c_z!)) | O(n * n!/(c_a!*...*c_z!)) | Hard | ||
| 0864 | Shortest Path to Get All Keys | C++ Python | O(k * r * c + k^3*2^k) | O(k*2^k) | Hard | Dijkstra's Algorithm |
|
| 0882 | Reachable Nodes In Subdivided Graph | C++ Python | O(|E| * log|V|) | O(|E|) | Hard | Dijkstra's Algorithm |
|
| 0886 | Possible Bipartition | C++ Python | O(|V| + |E|) | O(|V| + |E|) | Medium | ||
| 0913 | Cat and Mouse | C++ Python | O(n^3) | O(n^2) | Hard | MiniMax, Topological Sort | |
| 0934 | Shortest Bridge | C++ Python | O(n^2) | O(n^2) | Medium | BFS, DFS | |
| 0967 | Numbers With Same Consecutive Differences | C++ Python | O(2^n) | O(2^n) | Medium | ||
| 0994 | Rotting Oranges | C++ Python | O(m * n) | O(m * n) | Easy | ||
| 1034 | Coloring A Border | C++ Python | O(m * n) | O(m + n) | Medium | ||
| 1036 | Escape a Large Maze | C++ Python | O(n^2) | O(n) | Hard | ||
| 1091 | Shortest Path in Binary Matrix | C++ Python | O(n^2) | O(n) | Medium | ||
| 1102 | Path With Maximum Minimum Value | C++ Python | O((m * n) * log(m * n)) | O(m * n) | Medium | 🔒 | Binary Search, DFS, Dijkstra's Algorithm |
| 1129 | Shortest Path with Alternating Colors | C++ Python | O(n + e) | O(n + e) | Medium | ||
| 1136 | Parallel Courses | C++ Python | O(|V| + |E|) | O(|E|) | Hard | 🔒 | Topological Sort |
| 1161 | Maximum Level Sum of a Binary Tree | C++ Python | O(n) | O(w) | Medium | DFS | |
| 1162 | As Far from Land as Possible | C++ Python | O(m * n) | O(m * n) | Medium | ||
| 1203 | Sort Items by Groups Respecting Dependencies | C++ Python | O(n + e) | O(n + e) | Hard | Topological Sort | |
| 1210 | Minimum Moves to Reach Target with Rotations | C++ Python | O(n) | O(n) | Hard | ||
| 1215 | Stepping Numbers | C++ Python | O(logk + r) | O(k) | Medium | 🔒 | Precompute, Binary Search |
| 1245 | Tree Diameter | C++ Python | O(|V| + |E|) | O(|E|) | Medium | ||
| 1263 | Minimum Moves to Move a Box to Their Target Location | C++ Python | O(m^2 * n^2) | O(m^2 * n^2) | Hard | A* Search Algorithm |
|
| 1284 | Minimum Number of Flips to Convert Binary Matrix to Zero Matrix | C++ Python | O((m * n) * 2^(m * n)) | O((m * n) * 2^(m * n)) | Hard | ||
| 1291 | Sequential Digits | C++ Python | O(1) | O(1) | Medium | ||
| 1293 | Shortest Path in a Grid with Obstacles Elimination | C++ Python | O(m * n * k) | O(m * n) | Hard | A* Search Algorithm |
|
| 1298 | Maximum Candies You Can Get from Boxes | C++ Python | O(n^2) | O(n) | Hard | ||
| 1302 | Deepest Leaves Sum | C++ Python | O(n) | O(w) | Medium | ||
| 1306 | Jump Game III | C++ Python | O(n) | O(n) | Medium | ||
| 1311 | Get Watched Videos by Your Friends | C++ Python | O(n + vlogv) | O(w) | Medium | ||
| 1345 | Jump Game IV | C++ Python | O(n) | O(n) | Hard | ||
| 1368 | Minimum Cost to Make at Least One Valid Path in a Grid | C++ Python | O(m * n) | O(m * n) | Hard | A* Search Algorithm, 0-1 BFS, Deque |
|
| 1514 | Path with Maximum Probability | C++ Python | O(|E| * log|V|) | O(|E|) | Medium | Dijkstra's Algorithm |
|
| 1602 | Find Nearest Right Node in Binary Tree | C++ Python | O(n) | O(w) | Medium | 🔒 | |
| 1609 | Even Odd Tree | C++ Python | O(n) | O(w) | Medium | ||
| 1625 | Lexicographically Smallest String After Applying Operations | C++ Python | O(n^2) | O(1) | Medium | BFS, String | |
| 1654 | Minimum Jumps to Reach Home | C++ Python | O(max(x, max(forbidden)) + a + b) | O(max(x, max(forbidden)) + a + b) | Medium | BFS | |
| 1660 | Correct a Binary Tree | C++ Python | O(n) | O(w) | Medium | 🔒 | BFS |
| 1728 | Cat and Mouse II | C++ Python | O((m * n)^2 * (m + n)) | O((m * n)^2) | Hard | variant of Cat and Mouse | MiniMax, Topological Sort |
| 1730 | Shortest Path to Get Food | C++ Python | O(m * n) | O(m + n) | Medium | 🔒 | BFS |
| 1765 | Map of Highest Peak | C++ Python | O(m * n) | O(m * n) | Medium | BFS | |
| 1926 | Nearest Exit from Entrance in Maze | C++ Python | O(m * n) | O(m + n) | Medium | Bi-BFS | |
| 1928 | Minimum Cost to Reach Destination in Time | C++ Python | O(|E| * log|V|) | O(|E|) | Hard | variant of Cheapest Flights Within K Stops | Dijkstra's Algorithm |
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 0112 | Path Sum | Python | O(n) | O(h) | Easy | ||
| 0113 | Path Sum II | Python | O(n) | O(h) | Medium | ||
| 0199 | Binary Tree Right Side View | Python | O(n) | O(h) | Medium | ||
| 0200 | Number of Islands | C++ Python | O(m * n) | O(m * n) | Medium | BFS, DFS, Union Find | |
| 0236 | Lowest Common Ancestor of a Binary Tree | C++ Python | O(n) | O(h) | Medium | EPI | |
| 0247 | Strobogrammatic Number II | C++ Python | O(n * 5^(n/2)) | O(n) | Medium | 🔒 | |
| 0250 | Count Univalue Subtrees | C++ Python | O(n) | O(h) | Medium | 🔒 | |
| 0257 | Binary Tree Paths | C++ Python | O(n * h) | O(h) | Easy | ||
| 0282 | Expression Add Operators | C++ Python | O(4^n) | O(n) | Hard | ||
| 0301 | Remove Invalid Parentheses | C++ Python | O(C(n, c)) | O(c) | Hard | ||
| 0329 | Longest Increasing Path in a Matrix | C++ Python | O(m * n) | O(m * n) | Hard | DFS, Topological Sort | |
| 0332 | Reconstruct Itinerary | C++ Python | O(t! / (n1! * n2! * ... nk!)) | O(t) | Medium | ||
| 0339 | Nested List Weight Sum | C++ Python | O(n) | O(h) | Easy | 🔒 | |
| 0364 | Nested List Weight Sum II | C++ Python | O(n) | O(h) | Medium | 🔒 | |
| 0366 | Find Leaves of Binary Tree | C++ Python | O(n) | O(h) | Medium | 🔒 | |
| 0417 | Pacific Atlantic Water Flow | C++ Python | O(m * n) | O(m * n) | Medium | ||
| 0440 | K-th Smallest in Lexicographical Order | C++ Python | O(logn) | O(logn) | Hard | ||
| 0464 | Can I Win | C++ Python | O(n!) | O(n) | Medium | ||
| 0515 | Find Largest Value in Each Tree Row | C++ Python | O(n) | O(h) | Medium | ||
| 0547 | Friend Circles | C++ Python | O(n^2) | O(n) | Medium | Union Find | |
| 0582 | Kill Process | C++ Python | O(n) | O(n) | Medium | 🔒 | DFS, BFS |
| 0638 | Shopping Offers | C++ Python | O(n * 2^n) | O(n) | Medium | ||
| 0690 | Employee Importance | C++ Python | O(n) | O(h) | Easy | DFS, BFS | |
| 0694 | Number of Distinct Islands | C++ Python | O(m * n) | O(m * n) | Medium | 🔒 | |
| 0695 | Max Area of Island | C++ Python | O(m * n) | O(m * n) | Easy | ||
| 0711 | Number of Distinct Islands II | C++ Python | O((m * n) * log(m * n)) | O(m * n) | Hard | 🔒 | Hash |
| 0733 | Max Area of Island | C++ Python | O(m * n) | O(m * n) | Easy | ||
| 0749 | Contain Virus | C++ Python | O((m * n)^(4/3)) | O(m * n) | Hard | Simulation | |
| 0753 | Cracking the Safe | C++ Python | O(k^n) | O(k^n) | Hard | de Bruijn sequences, Lyndon word, Rolling Hash, Backtracking, Greedy |
|
| 0756 | Pyramid Transition Matrix | C++ Python | O(a^b) | O(a^b) | Medium | ||
| 0785 | Is Graph Bipartite? | C++ Python | O(|V| + |E|) | O(|V|) | Medium | ||
| 0797 | All Paths From Source to Target | C++ Python | O(p + r * n) | O(n) | Medium | ||
| 0802 | Find Eventual Safe States | C++ Python | O(|V| + |E|) | O(|V|) | Medium | ||
| 0827 | Making A Large Island | C++ Python | O(n^2) | O(n^2) | Hard | ||
| 0834 | Sum of Distances in Tree | C++ Python | O(n) | O(n) | Hard | ||
| 0841 | Keys and Rooms | C++ Python | O(n!) | O(n) | Medium | ||
| 0851 | Loud and Rich | C++ Python | O(q + r) | O(q + r) | Medium | ||
| 1020 | Number of Enclaves | C++ Python | O(m * n) | O(m * n) | Medium | ||
| 1059 | All Paths from Source Lead to Destination | C++ Python | O(n + e) | O(n + e) | Medium | 🔒 | |
| 1192 | Critical Connections in a Network | C++ Python | O(|V| + |E|) | O(|V| + |E|) | Hard | Tarjan's Algorithm, Bridge Finding Algorithm |
|
| 1202 | Smallest String With Swaps | C++ Python | O(nlogn) | O(n) | Medium | Union Find | |
| 1254 | Number of Closed Islands | C++ Python | O(m * n) | O(1) | Medium | ||
| 1273 | Delete Tree Nodes | C++ Python | O(n) | O(n) | Medium | DFS, DP | |
| 1315 | Sum of Nodes with Even-Valued Grandparent | C++ Python | O(n) | O(h) | Medium | ||
| 1319 | Number of Operations to Make Network Connected | C++ Python | O(|E| + |V|) | O(|V|) | Medium | Union Find | |
| 1367 | Linked List in Binary Tree | C++ Python | O(n + l) | O(h + l) | Medium | KMP Algorithm |
|
| 1372 | Longest ZigZag Path in a Binary Tree | C++ Python | O(n) | O(h) | Medium | ||
| 1376 | Time Needed to Inform All Employees | C++ Python | O(n) | O(n) | Medium | ||
| 1377 | Frog Position After T Seconds | C++ Python | O(n) | O(n) | Hard | DFS, Stack, BFS | |
| 1391 | Check if There is a Valid Path in a Grid | C++ Python | O(m * n) | O(1) | Medium | Simulation | |
| 1466 | Reorder Routes to Make All Paths Lead to the City Zero | C++ Python | O(n) | O(n) | Medium | DFS, Stack | |
| 1485 | Clone Binary Tree With Random Pointer | C++ Python | O(n) | O(h) | Medium | 🔒 | DFS, Stack |
| 1644 | Lowest Common Ancestor of a Binary Tree II | C++ Python | O(n) | O(h) | Medium | 🔒 | DFS, Stack |
| 1676 | Lowest Common Ancestor of a Binary Tree IV | C++ Python | O(n) | O(h) | Medium | 🔒 | DFS, Stack |
| 1722 | Minimize Hamming Distance After Swap Operations | C++ Python | O(n) | O(n) | Medium | Flood Fill, Union Find | |
| 1740 | Find Distance in a Binary Tree | C++ Python | O(n) | O(h) | Medium | variant of Lowest Common Ancestor of a Binary Tree, 🔒 | |
| 1766 | Tree of Coprimes | C++ Python | O(n) | O(n) | Hard | ||
| 1905 | Count Sub Islands | C++ Python | O(m * n) | O(1) | Medium | Flood Fill | |
| 1973 | Count Nodes Equal to Sum of Descendants | C++ Python | O(n) | O(h) | Medium | 🔒 |
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 0017 | Letter Combinations of a Phone Number | C++ Python | O(n * 4^n) | O(1) | Medium | ||
| 0022 | Generate Parentheses | C++ Python | O(4^n / n^(3/2)) | O(n) | Medium | ||
| 0037 | Sudoku Solver | Python | O((9!)^9) | O(1) | Hard | ||
| 0039 | Combination Sum | Python | O(k * n^k) | O(k) | Medium | ||
| 0040 | Combination Sum II | Python | O(k * C(n, k)) | O(k) | Medium | ||
| 0046 | Permutations | Python | O(n * n!) | O(n) | Medium | ||
| 0047 | Permutations II | Python | O(n * n!) | O(n) | Medium | ||
| 0051 | N-Queens | Python | O(n!) | O(n) | Hard | ||
| 0052 | N-Queens-II | Python | O(n!) | O(n) | Hard | ||
| 0077 | Combinations | C++ Python | O(O(k * C(n, k))) | O(k) | Medium | ||
| 0079 | Word Search | C++ Python | O(m * n * 3^l) | O(l) | Medium | ||
| 0093 | Restore IP Addresses | Python | O(1) | O(1) | Medium | ||
| 0078 | Subsets | C++ Python | O(n * 2^n) | O(1) | Medium | ||
| 0090 | Subsets II | C++ Python | O(n * 2^n) | O(1) | Medium | ||
| 0126 | Word Ladder II | C++ Python | O(b^(d/2)) | O(w * l) | Hard | CTCI | Bi-BFS |
| 0131 | Palindrome Partitioning | Python | O(n^2) ~ O(2^n) | O(n^2) | Medium | ||
| 0140 | Word Break II | C++ Python | O(n * l^2 + n * r) | O(n^2) | Hard | ||
| 0212 | Word Search II | C++ Python | O(m * n * 3^h) | O(t) | Hard | LintCode | Trie, DFS |
| 0216 | Combination Sum III | C++ Python | O(k * C(n, k)) | O(k) | Medium | ||
| 0254 | Factor Combinations | C++ Python | O(nlogn) | O(logn) | Medium | 🔒 | |
| 0267 | Palindrome Permutation II | C++ Python | O(n * n!) | O(n) | Medium | 🔒 | |
| 0291 | Word Pattern II | C++ Python | O(n * C(n - 1, c - 1)) | O(n + c) | Hard | 🔒 | |
| 0294 | Flip Game II | C++ Python | O(n + c^2) | O(c) | Medium | 🔒 | DP, Hash |
| 0320 | Generalized Abbreviation | C++ Python | O(n * 2^n) | O(n) | Medium | 🔒 | |
| 0425 | Word Squares | C++ Python | O(n^2 * n!) | O(n^2) | Hard | 🔒 | |
| 0488 | Zuma Game | C++ Python | O((b+h) * h!*(b+h-1)!/(b-1)!) | O((b+h) * h!*(b+h-1)!/(b-1)!) | Hard | Backtracking | |
| 0491 | Increasing Subsequences | C++ Python | O(n * 2^n) | O(n) | Medium | Backtracking | |
| 0526 | Beautiful Arrangement | C++ Python | O(n!) | O(n) | Medium | ||
| 0676 | Implement Magic Dictionary | C++ Python | O(n) | O(d) | Medium | Trie, DFS | |
| 0679 | 24 Game | C++ Python | O(1) | O(1) | Hard | DFS | |
| 0698 | Partition to K Equal Sum Subsets | C++ Python | O(n * 2^n) | O(2^n) | Medium | DFS, DP, Memoization | |
| 0718 | Maximum Length of Repeated Subarray | C++ Python | O(m * n) | O(min(m, n)) | Medium | DP, Hash, Binary Search | |
| 0784 | Letter Case Permutation | C++ Python | O(n * 2^n) | O(1) | Easy | ||
| 0996 | Number of Squareful Arrays | C++ Python | O(n!) | O(n^2) | Hard | ||
| 1087 | Brace Expansion | C++ Python | O(p * l * log(p * l)) | O(p * l) | Medium | 🔒 | |
| 1096 | Brace Expansion II | C++ Python | O(p * l * log(p * l)) | O(p * l) | Hard | ||
| 1219 | Path with Maximum Gold | C++ Python | O(m^2 * n^2) | O(m * n) | Medium | ||
| 1240 | Tiling a Rectangle with the Fewest Squares | C++ Python | O(n^2 * m^2 * m^(n * m)) | O(n * m) | Hard | ||
| 1255 | Maximum Score Words Formed by Letters | C++ Python | O(n * 2^n) | O(n) | Hard | ||
| 1258 | Synonymous Sentences | C++ Python | O(p * l * log(p * l)) | O(p * l) | Medium | Union Find | |
| 1307 | Verbal Arithmetic Puzzle | C++ Python | O(10! * n * l) | O(n * l) | Hard | ||
| 1379 | Find a Corresponding Node of a Binary Tree in a Clone of That Tree | C++ Python | O(n) | O(h) | Medium | Stack | |
| 1593 | Split a String Into the Max Number of Unique Substrings | C++ Python | O(n * 2^(n - 1)) | O(n) | Medium | ||
| 1659 | Maximize Grid Happiness | C++ Python | O(C(m * n, i) * C(m * n - i, e)) | O(min(m * n, i + e)) | Hard | Pruning | |
| 1718 | Construct the Lexicographically Largest Valid Sequence | C++ Python | O(n!) | O(b) | Medium | Backtracking | |
| 1723 | Find Minimum Time to Finish All Jobs | C++ Python | O(k^n * logr) | O(n + k) | Hard | Backtracking, Pruning, Binary Search | |
| 1849 | Splitting a String Into Descending Consecutive Values | C++ Python | O(n^2) | O(n) | Medium | ||
| 1999 | Smallest Greater Multiple Made of Two Digits | C++ Python | O(1) | O(1) | Medium | 🔒 | Backtracking, Bit Manipulation |
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 0399 | Evaluate Division | C++ Python | O(e + q) | O(e) | Medium | Floyd-Warshall Algorithm, BFS, Union Find |
|
| 0765 | Couples Holding Hands | C++ Python | O(n) | O(n) | Hard | ||
| 0924 | Minimize Malware Spread | C++ Python | O(n^2) | O(n) | Hard | Union Find | |
| 0928 | Minimize Malware Spread II | C++ Python | O(n^2) | O(n) | Hard | Union Find | |
| 0959 | Regions Cut By Slashes | C++ Python | O(n^2) | O(n^2) | Medium | Union Find | |
| 0990 | Satisfiability of Equality Equations | C++ Python | O(n) | O(1) | Medium | Union Find | |
| 1042 | Flower Planting With No Adjacent | C++ Python | O(n) | O(n) | Easy | ||
| 1101 | The Earliest Moment When Everyone Become Friends | C++ Python | O(nlogn) | O(n) | Medium | 🔒 | Union Find |
| 1135 | Connecting Cities With Minimum Cost | C++ Python | O(nlogn) | O(n) | Medium | 🔒 | Union Find, Kruskal's Algorithm, MST |
| 1168 | Optimize Water Distribution in a Village | C++ Python | O(nlogn) | O(n) | Hard | 🔒 | Union Find |
| 1334 | Find the City With the Smallest Number of Neighbors at a Threshold Distance | C++ Python | O(n^3) | O(n^2) | Medium | Floyd-Warshall Algorithm |
|
| 1361 | Validate Binary Tree Nodes | C++ Python | O(n) | O(n) | Medium | DFS, Tree | |
| 1462 | Course Schedule IV | C++ Python | O(n^3) | O(n^2) | Medium | Floyd-Warshall Algorithm |
|
| 1489 | Find Critical and Pseudo-Critical Edges in Minimum Spanning Tree | C++ Python | O(nlogn) | O(n) | Hard | Kruskal Algorithm |
|
| 1557 | Minimum Number of Vertices to Reach All Nodes | C++ Python | O(e) | O(n) | Medium | ||
| 1579 | Remove Max Number of Edges to Keep Graph Fully Traversable | C++ Python | O(n + m) | O(n) | Hard | Union Find | |
| 1584 | Min Cost to Connect All Points | C++ Python | O(n^2) | O(n) | Medium | Union Find, Kruskal's Algorithm, MST |
|
| 1601 | Maximum Number of Achievable Transfer Requests | C++ Python | O((n + r) * 2^r) | O(n + r) | Hard | Combinations, Backtracking | |
| 1615 | Maximal Network Rank | C++ Python | O(m + n + k^2) | O(m + n) | Medium | Counting Sort | |
| 1627 | Graph Connectivity With Threshold | C++ Python | O(nlogn + q) | O(n) | Hard | Union Find, Math | |
| 1631 | Path With Minimum Effort | C++ Python | O(m * n * log(m * n)) | O(m * n) | Medium | Binary Search, DFS, BFS, Bi-BFS, Union Find, Dijkstra's Algorithm |
|
| 1697 | Checking Existence of Edge Length Limited Paths | C++ Python | O(nlogn + mlogm) | O(n) | Hard | Union Find | |
| 1719 | Number Of Ways To Reconstruct A Tree | C++ Python | O(nlogn) | O(n) | Hard | ||
| 1724 | Checking Existence of Edge Length Limited Paths II | C++ Python | ctor: O(nlogn + mlogm) query: O(logn) |
O(nlogn + m) | Hard | 🔒 | Versioned Union Find, Binary Lifting |
| 1743 | Restore the Array From Adjacent Pairs | C++ Python | O(n) | O(n) | Medium | ||
| 1761 | Minimum Degree of a Connected Trio in a Graph | C++ Python | O(n^3) | O(n^2) | Hard | ||
| 1778 | Shortest Path in a Hidden Grid | C++ Python | O(m * n) | O(m * n) | Medium | 🔒 | DFS, BFS, Bi-BFS |
| 1782 | Count Pairs Of Nodes | C++ Python | O(n + e + q) | O(n + e) | Hard | Counting, Two Pointers | |
| 1786 | Number of Restricted Paths From First to Last Node | C++ Python | O(|E| * log|V|) | O(|E|) | Medium | Dijkstra's Algorithm, DP |
|
| 1791 | Find Center of Star Graph | C++ Python | O(n) | O(n) | Medium | ||
| 1810 | Minimum Path Cost in a Hidden Grid | C++ Python | O(m * n * log(m * n)) | O(m * n) | Medium | 🔒 | DFS, Dijkstra's Algorithm |
| 1820 | Maximum Number of Accepted Invitations | C++ Python | O(m * n * sqrt(m + n)) | O(m + n) | Medium | 🔒 | Hopcroft-Karp Bipartite Matching, Hungarian Bipartite Matching |
| 1879 | Minimum XOR Sum of Two Arrays | C++ Python | O(n^3) | O(n^2) | Hard | DP, Hungarian Weighted Bipartite Matching |
|
| 1947 | Maximum Compatibility Score Sum | C++ Python | O(m^2 * (n + m)) | O(m^2) | Medium | variant of Minimum XOR Sum of Two Arrays | DP, Hungarian Weighted Bipartite Matching |
| 1971 | Find if Path Exists in Graph | C++ Python | O(|V| + |E|) | O(|V| + |E|) | Easy | DFS, BFS, Bi-BFS | |
| 1976 | Number of Ways to Arrive at Destination | C++ Python | O(|E| * log|V|) | O(|E|) | Medium | Dijkstra's Algorithm |
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 0587 | Erect the Fence | C++ Python | O(nlogn) | O(n) | Hard | Convex Hull, Monotone Chain |
|
| 0892 | Surface Area of 3D Shapes | C++ Python | O(n^2) | O(1) | Easy | ||
| 1453 | Maximum Number of Darts Inside of a Circular Dartboard | C++ Python | O(n^2 * logn) | O(n) | Hard | Line Sweep | |
| 1515 | Best Position for a Service Centre | C++ Python | O(n * iter) | O(n) | Hard | Geometric Median, Gradient Descent, Weiszfeld's Algorithm | |
| 1610 | Maximum Number of Visible Points | C++ Python | O(nlogn) | O(n) | Hard | Two Pointers, Sliding Window | |
| 1924 | Erect the Fence II | C++ Python | O(n) on average | O(n) | Hard | 🔒 | Welzl's Algorithm |
| 1956 | Minimum Time For K Virus Variants to Spread | C++ Python | O(nlogn * logr) | O(n) | Hard | 🔒 | Geometry, Binary Search, Line Sweep, Segment Tree, Coordinate Compression |
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 0874 | Walking Robot Simulation | C++ Python | O(n + k) | O(k) | Easy | ||
| 1138 | Alphabet Board Path | C++ Python | O(n) | O(1) | Medium | ||
| 1243 | Array Transformation | C++ Python | O(n^2) | O(n) | Easy |
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 0146 | LRU Cache | C++ Python | O(1) | O(k) | Hard | OrderedDict | |
| 0225 | Implement Stack using Queues | C++ Python | push: O(n), pop: O(1), top: O(1) | O(n) | Easy | ||
| 0173 | Binary Search Tree Iterator | C++ Python | O(1), amortized | O(h) | Medium | ||
| 0284 | Peeking Iterator | C++ Python | O(1) | O(1) | Medium | ||
| 0348 | Design Tic-Tac-Toe | C++ Python | O(1) | O(n^2) | Medium | 🔒 | |
| 0353 | Design Snake Game | C++ Python | O(1) | O(s) | Medium | 🔒 | Deque |
| 0355 | Design Twitter | C++ Python | O(klogu) | O(t + f) | Medium | LintCode | Heap |
| 0359 | Logger Rate Limiter | C++ Python | O(1), amortized | O(k) | Easy | 🔒 | Deque |
| 0362 | Design Hit Counter | C++ Python | O(1), amortized | O(k) | Medium | 🔒 | Deque |
| 0379 | Design Phone Directory | C++ Python | O(1) | O(n) | Medium | 🔒 | |
| 0380 | Insert Delete GetRandom O(1) | C++ Python | O(1) | O(n) | Hard | ||
| 0381 | Insert Delete GetRandom O(1) - Duplicates allowed | C++ Python | O(1) | O(n) | Hard | ||
| 0432 | All O`one Data Structure | C++ Python | O(1) | O(n) | Hard | ||
| 0460 | LFU Cache | C++ Python | O(1) | O(k) | Hard | ||
| 0489 | Robot Room Cleaner | C++ Python | O(n) | O(n) | Hard | 🔒 | |
| 0535 | Encode and Decode TinyURL | C++ Python | O(1) | O(n) | Medium | ||
| 0588 | Design In-Memory File System | C++ Python | ls: O(l + klogk) mkdir: O(l) addContentToFile: O(l + c) readContentFromFile: O(l + c) |
O(n + s) | Hard | 🔒 | |
| 0604 | Design Compressed String Iterator | C++ Python | O(1) | O(1) | Easy | 🔒 | |
| 0622 | Design Circular Queue | C++ Python | O(1) | O(k) | Medium | Design | |
| 0631 | Design Excel Sum Formula | C++ Python | set: O((r * c)^2) get: O(1) sum: O((r * c)^2) |
O(r * c) | Hard | 🔒 | |
| 0635 | Design Log Storage System | C++ Python | put: O(1) retrieve: O(n + dlogd) |
O(n) | Medium | 🔒 | |
| 0641 | Design Circular Deque | C++ Python | O(1) | O(1) | Medium | Design | |
| 0642 | Design Search Autocomplete System | C++ Python | O(p^2) | O(p * t + s) | Hard | 🔒 | |
| 0705 | Design HashSet | C++ Python | O(1) | O(n) | Easy | Design | |
| 0706 | Design HashMap | C++ Python | O(1) | O(n) | Easy | Design | |
| 0707 | Design Linked List | C++ Python | O(n) | O(n) | Medium | Design | |
| 0715 | Range Module | C++ Python | add: O(n) remove: O(n) query: O(logn) |
O(n) | Hard | ||
| 0716 | Max Stack | C++ Python | push: O(logn) pop: O(logn) popMax: O(logn) top: O(1) peekMax: O(1) |
O(n) | Easy | ||
| 0745 | Prefix and Suffix Search | C++ Python | ctor: O(w * l^2) search : O(p + s) |
O(t) | Hard | Trie | |
| 0900 | RLE Iterator | C++ Python | O(n) | O(1) | Medium | ||
| 1146 | Snapshot Array | C++ Python | set: O(1) get: O(logn) |
O(n) | Medium | ||
| 1166 | Design File System | C++ Python | create: O(n) get: O(n) |
O(n) | Medium | 🔒 | |
| 1172 | Dinner Plate Stacks | C++ Python | push: O(logn) pop: O(1), amortized popAtStack: (logn) |
O(n * c) | Hard | ||
| 1206 | Design Skiplist | C++ Python | O(logn), on average | O(n) | Hard | ||
| 1236 | Web Crawler | C++ Python | O(|V| + |E|) | O(|V|) | Medium | 🔒 | BFS, DFS |
| 1244 | Design A Leaderboard | C++ Python | ctor: O(1) add: O(1) top: O(n) reset: O(1) |
O(n) | Medium | ||
| 1268 | Search Suggestions System | C++ Python | ctor: O(n * l) suggest: O(l^2) |
O(t) | Medium | Trie | |
| 1286 | Iterator for Combination | C++ Python | O(k) | O(k) | Medium | Stack | |
| 1348 | Tweet Counts Per Frequency | C++ Python | add: O(logn) query: O(c) |
O(n) | Medium | ||
| 1352 | Product of the Last K Numbers | C++ Python | ctor: O(1) add: O(1) get: O(1) |
O(n) | Medium | ||
| 1357 | Apply Discount Every n Orders | C++ Python | ctor: O(m) getBill: O(p) |
O(m) | Medium | ||
| 1381 | Design a Stack With Increment Operation | C++ Python | ctor: O(1) push: O(1) pop: O(1) increment: O(1) |
O(n) | Medium | ||
| 1396 | Design Underground System | C++ Python | ctor: O(1) checkin: O(1) checkout: O(1) getaverage: O(1) |
O(n) | Medium | ||
| 1429 | First Unique Number | C++ Python | ctor: O(k) add: O(1) showFirstUnique: O(1) |
O(n) | Medium | 🔒 | LinkedHashSet |
| 1472 | Design Browser History | C++ Python | ctor: O(1) visit: O(1) back: O(1) forward: O(1) |
O(n) | Medium | ||
| 1476 | Subrectangle Queries | C++ Python | ctor: O(1) update: O(1) get: O(u) |
O(u) | Medium | ||
| 1483 | Kth Ancestor of a Tree Node | C++ Python | ctor: O(n * logh) get: O(logh) |
O(n * logh) | Hard | DP, Binary Lifting | |
| 1500 | Design a File Sharing System | C++ Python | ctor: O(1) join: O(logu + c) leave: O(logu + c) request: O(u) |
O(u * c) | Medium | 🔒 | |
| 1570 | Dot Product of Two Sparse Vectors | C++ Python | ctor: O(n) dot_product: O(min(n, m)) |
O(n) | Medium | 🔒 | |
| 1586 | Binary Search Tree Iterator II | C++ Python | O(1), amortized | O(h) | Medium | 🔒 | |
| 1600 | Throne Inheritance | C++ Python | ctor: O(1) birth: O(1) death: O(1) inherit: O(n) |
O(n) | Medium | ||
| 1603 | Design Parking System | C++ Python | O(1) | O(1) | Easy | ||
| 1622 | Fancy Sequence | C++ Python | O(1) | O(n) | Hard | Euler's Theorem |
|
| 1628 | Design an Expression Tree With Evaluate Function | C++ Python | O(n) | O(h) | Medium | 🔒 | |
| 1656 | Design an Ordered Stream | C++ Python | O(1), amortized | O(n) | Easy | ||
| 1670 | Design Front Middle Back Queue | C++ Python | O(1) | O(n) | Medium | ||
| 1756 | Design Most Recently Used Queue | C++ Python | ctor: O(nlogn) fetch: O(logn) |
O(n) | Medium | 🔒 | SortedList, BIT, Fenwick Tree, Square Root Decomposition |
| 1797 | Design Authentication Manager | C++ Python | ctor: O(1) generate: O(1), amortized renew: O(1), amortized count: O(1), amortized |
O(n) | Medium | OrderedDict | |
| 1804 | Implement Trie II (Prefix Tree) | C++ Python | ctor: O(1) insert: O(n) count_word: O(n) count_prefix: O(n) erase: O(n) |
O(t) | Medium | 🔒 | Trie |
| 1825 | Finding MK Average | C++ Python | ctor: O(1) add_element: O(logn) calc_mkaverge: O(1) |
O(m) | Hard | SortedList | |
| 1845 | Seat Reservation Manager | C++ Python | ctor: O(n) reserve: O(logn) unreserve: O(logn) |
O(n) | Medium | Heap | |
| 1865 | Finding Pairs With a Certain Sum | C++ Python | ctor: O(n1 + n2) add: O(1) count: O(n1) |
O(n1 + n2) | Medium | Hash Table | |
| 1912 | Design Movie Rental System | C++ Python | ctor: O(nlogn) search: O(logn) rent: O(logn) drop: O(logn) report: O(logn) |
O(n) | Hard | Ordered List | |
| 1993 | Operations on Tree | C++ Python | ctor: O(n) lock: O(1) unlock: O(1) upgrade: O(n) |
O(n) | Medium |
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 1114 | Print in Order | C++ Python | O(n) | O(1) | Easy | ||
| 1115 | Print FooBar Alternately | C++ Python | O(n) | O(1) | Medium | ||
| 1116 | Print Zero Even Odd | C++ Python | O(n) | O(1) | Medium | ||
| 1117 | Building H2O | C++ Python | O(n) | O(1) | Hard | ||
| 1188 | Design Bounded Blocking Queue | C++ Python | O(n) | O(1) | Medium | 🔒 | |
| 1195 | Fizz Buzz Multithreaded | C++ Python | O(n) | O(1) | Medium | ||
| 1226 | The Dining Philosophers | C++ Python | O(n) | O(1) | Medium | ||
| 1242 | Web Crawler Multithreaded | C++ Python | O(|V| + |E|) | O(|V|) | Medium | 🔒 | |
| 1279 | Traffic Light Controlled Intersection | C++ Python | O(n) | O(1) | Easy | 🔒 |
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 0192 | Word Frequency | Shell | O(n) | O(k) | Medium | ||
| 0193 | Valid Phone Numbers | Shell | O(n) | O(1) | Easy | ||
| 0194 | Transpose File | Shell | O(n^2) | O(n^2) | Medium | ||
| 0195 | Tenth Line | Shell | O(n) | O(1) | Easy |