- 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, GoogleCodeJamIO repositories.
- For more challenging problem solutions, you can also see my GoogleCodeJam, MetaHackerCup 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(n×2n/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 |
|---|---|---|---|---|---|---|---|
| 1310 | XOR Queries of a Subarray | C++ Python | O(n) | O(1) | Medium | ||
| 1318 | Minimum Flips to Make a OR b Equal to c | C++ Python | O(1) | O(1) | Medium | ||
| 1342 | Number of Steps to Reduce a Number to Zero | C++ Python | O(logn) | O(1) | Easy | ||
| 1558 | Minimum Numbers of Function Calls to Make Target Array | C++ Python | O(nlogn) | O(1) | Medium | Greedy | |
| 1707 | Maximum XOR With an Element From Array | C++ Python | O(nlogn + mlogm + nlogk + mlogk) | O(nlogk) | Hard | variant of Maximum XOR of Two Numbers in an Array | Greedy, Trie |
| 1720 | Decode XORed Array | C++ Python | O(n) | O(1) | Easy | ||
| 1734 | Decode XORed Permutation | C++ Python | O(n) | O(1) | Medium | ||
| 1829 | Maximum XOR for Each Query | C++ Python | O(n) | O(1) | Medium | ||
| 2151 | Maximum Good People Based on Statements | C++ Python | O(n^2 * 2^n) | O(1) | Hard | Bitmasks, Brute Force | |
| 2212 | Maximum Points in an Archery Competition | C++ Python | O(n * 2^n) | O(n) | Medium | Bitmasks, Brute Force | |
| 2220 | Minimum Bit Flips to Convert Number | C++ Python | O(logn) | O(1) | Easy | Bit Manipulation | |
| 2275 | Largest Combination With Bitwise AND Greater Than Zero | C++ Python | O(nlogr) | O(logr) | Medium | Bit Manipulation, Freq Table | |
| 2317 | Maximum XOR After Operations | C++ Python | O(n) | O(1) | Medium | Bit Manipulation, Greedy | |
| 2397 | Maximum Rows Covered by Columns | C++ Python | O(m * n + m * C(n, k)) | O(m) | Medium | Bitmasks, Hakmem Item 175 |
|
| 2411 | Smallest Subarrays With Maximum Bitwise OR | C++ Python | O(n) | O(1) | Medium | Bitmasks, Hash Table | |
| 2419 | Longest Subarray With Maximum Bitwise AND | C++ Python | O(n) | O(1) | Medium | Bit Manipulation | |
| 2425 | Bitwise XOR of All Pairings | C++ Python | O(n) | O(1) | Medium | Bit Manipulation | |
| 2429 | Minimize XOR | C++ Python | O(logn) | O(1) | Medium | Bit Manipulation, Greedy |
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 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 | |
| 2398 | Maximum Number of Robots Within Budget | C++ Python | O(n) | O(n) | Hard | Mono Deque, Sliding Window, Two Pointers |
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 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 | Sorted List | |
| 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 | ||
| 2054 | Two Best Non-Overlapping Events | C++ Python | O(nlogn) | O(n) | Medium | Line Sweep, Heap | |
| 2163 | Minimum Difference in Sums After Removal of Elements | C++ Python | O(nlogn) | O(n) | Hard | Heap, Prefix Sum | |
| 2208 | Minimum Operations to Halve Array Sum | C++ Python | O(nlogn) | O(n) | Medium | Heap | |
| 2386 | Find the K-Sum of an Array | C++ Python | O(nlogn + klogk) | O(n + k) | Hard | BFS, Heap | |
| 2402 | Meeting Rooms III | C++ Python | O(mlogm + n + mlogn) | O(n) | Hard | Heap | |
| 2462 | Total Cost to Hire K Workers | C++ Python | O(c + klogc) | O(c) | Medium | Heap, Two Pointers |
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 1106 | Parsing A Boolean Expression | C++ Python | O(n) | O(n) | Hard |
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 1373 | Maximum Sum BST in Binary Tree | C++ Python | O(n) | O(h) | Hard | DFS, Stack | |
| 1382 | Balance a Binary Search Tree | C++ Python | O(n) | O(h) | Medium | DFS, Stack | |
| 1902 | Depth of BST Given Insertion Order | C++ Python | O(nlogn) | O(n) | Medium | 🔒 | Sorted Dict |
| 1932 | Merge BSTs to Create Single BST | C++ Python | O(n) | O(n) | Hard | BST, BFS | |
| 2426 | Number of Pairs Satisfying Inequality | C++ Python | O(nlogn) | O(n) | Hard | Merge Sort, Two Pointers, BIT, Fenwick Tree, Coordinate Compression, Sorted List, Ordered Set, Binary Search |
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 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 |
| 2039 | The Time When the Network Becomes Idle | C++ Python | O(|E|) | O(|E|) | Medium | Math | |
| 2045 | Second Minimum Time to Reach Destination | C++ Python | O(|E|) | O(|E|) | Hard | Bi-BFS | |
| 2050 | Parallel Courses III | C++ Python | O(|V| + |E|) | O(|E|) | Hard | variant of Parallel Courses | Topological Sort |
| 2059 | Minimum Operations to Convert Number | C++ Python | O(m * n) | O(m) | Medium | ||
| 2115 | Find All Possible Recipes from Given Supplies | C++ Python | O(|E|) | O(|E|) | Medium | Topological Sort | |
| 2146 | K Highest Ranked Items Within a Price Range | C++ Python | O(m * n + klogk) | O(m * n) | Medium | BFS, Quick Select, Sort | |
| 2258 | Escape the Spreading Fire | C++ Python | O(m * n) | O(m * n) | Hard | BFS | |
| 2290 | Minimum Obstacle Removal to Reach Corner | C++ Python | O(m * n) | O(m * n) | Hard | variant of Minimum Cost to Make at Least One Valid Path in a Grid | A* Search Algorithm, 0-1 BFS, Deque |
| 2316 | Count Unreachable Pairs of Nodes in an Undirected Graph | C++ Python | O(n) | O(n) | Medium | Flood Fill, BFS, Math | |
| 2368 | Reachable Nodes With Restrictions | C++ Python | O(n) | O(n) | Medium | BFS | |
| 2415 | Reverse Odd Levels of Binary Tree | C++ Python | O(n) | O(n) | Medium | BFS | |
| 2471 | Minimum Number of Operations to Sort a Binary Tree by Level | C++ Python | O(nlogn) | O(w) | Medium | Sort, BFS |
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 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 |
| 2014 | Longest Subsequence Repeated k Times | C++ Python | O(n * (n/k)!) | O(n/k) | Hard | ||
| 2056 | Number of Valid Move Combinations On Chessboard | C++ Python | O(1) | O(1) | Hard | ||
| 2094 | Finding 3-Digit Even Numbers | C++ Python | O(n) | O(1) | Easy | ||
| 2443 | Sum of Number and Its Reverse | C++ Python | O(n^(1/(2*log2(10)))) | O(log10(n)/2) | Medium | Brute Force, Backtracking |
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 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 |
|
| 1349 | Maximum Students Taking Exam | C++ Python | O(m * n * sqrt(m * n)) | O(m + n) | Hard | GCJ2008 - Round 3 | Hopcroft-Karp Bipartite Matching, Hungarian Bipartite Matching, Maximum Independent Set |
| 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 |
|
| 2076 | Process Restricted Friend Requests | C++ Python | O(n * r) | O(n) | Hard | Union Find | |
| 2077 | Paths in Maze That Lead to Same Room | C++ Python | O(|V|^3) | O(|E|) | Medium | 🔒 | |
| 2092 | Find All People With Secret | C++ Python | O(nlogn) | O(nlogn) | Hard | BFS, DFS, Union Find | |
| 2093 | Minimum Path Cost in a Hidden Grid | C++ Python | O(|E| * log|V|) | O(|V| + |E|) | Medium | variant of Cheapest Flights Within K Stops, 🔒 | Dijkstra's Algorithm, DP |
| 2097 | Valid Arrangement of Pairs | C++ Python | O(|V| + |E|) | O(|V| + |E|) | Hard | variant of Reconstruct Itinerary | Hierholzer's Algorithm, Eulerian Path |
| 2123 | Minimum Operations to Remove Adjacent Ones in Matrix | C++ Python | O(m * n * sqrt(m * n)) | O(m + n) | Hard | variant of Maximum Students Taking Exam, 🔒 | Hopcroft-Karp Bipartite Matching, Maximum Independent Set |
| 2127 | Maximum Employees to Be Invited to a Meeting | C++ Python | O(n) | O(n) | Hard | ||
| 2172 | Maximum AND Sum of Array | C++ Python | O(n^3) | O(n^2) | Hard | variant of Maximum Compatibility Score Sum | DP, Hungarian Weighted Bipartite Matching |
| 2203 | Minimum Weighted Subgraph With the Required Paths | C++ Python | O(|E| * log|V|) | O(|E|) | Hard | Dijkstra's Algorithm |
|
| 2204 | Distance to a Cycle in Undirected Graph | C++ Python | O(|V| + |E|) | O(|V| + |E|) | Hard | 🔒 | Graph, DFS, BFS |
| 2242 | Maximum Score of a Node Sequence | C++ Python | O(|V| + |E|) | O(|V|) | Hard | Graph | |
| 2307 | Check for Contradictions in Equations | C++ Python | O(e + q) | O(n) | Hard | 🔒, variant of Evaluate Division | DFS, Union Find |
| 2359 | Find Closest Node to Given Two Nodes | C++ Python | O(n) | O(n) | Medium | Graph, Hash Table, DFS | |
| 2360 | Longest Cycle in a Graph | C++ Python | O(n) | O(n) | Hard | Graph, Hash Table, DFS | |
| 2392 | Build a Matrix With Conditions | C++ Python | O(k^2 + r + c) | O(k + r + c) | Hard | Graph, Topological Sort | |
| 2473 | Minimum Cost to Buy Apples | C++ Python | O(n * rlogn) | O(n) | Medium | 🔒 | Dijkstra's Algorithm |
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 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 |
| 2101 | Detonate the Maximum Bombs | C++ Python | O(|V|^2 + \V| * |E|) | O(\V| + |E|) | Medium | Graph, DFS, BFS |
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 1138 | Alphabet Board Path | C++ Python | O(n) | O(1) | Medium | ||
| 1243 | Array Transformation | C++ Python | O(n^2) | O(n) | Easy | ||
| 2061 | Number of Spaces Cleaning Robot Cleaned | C++ Python | O(m * n) | O(1) | Medium | 🔒 | |
| 2162 | Minimum Cost to Set Cooking Time | C++ Python | O(1) | O(1) | Medium | ||
| 2257 | Count Unguarded Cells in the Grid | C++ Python | O(m * n) | O(m * n) | Medium | Array, Simulation | |
| 2303 | Calculate Amount Paid in Taxes | C++ Python | O(n) | O(1) | Easy | Simulation |
| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|---|
| 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 | 🔒 | Sorted List, 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 | Sorted List | |
| 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 | ||
| 2013 | Detect Squares | C++ Python | ctor: O(1) add: O(1) count: O(n) |
O(n) | Medium | ||
| 2034 | Stock Price Fluctuation | C++ Python | ctor: O(1) update: O(logn) current: O(1) max: O(1) min: O(1) |
O(n) | Medium | Sorted List, Heap | |
| 2043 | Simple Bank System | C++ Python | ctor: O(1) transer: O(1) deposit: O(1) withdraw: O(1) |
O(1) | Medium | ||
| 2069 | Walking Robot Simulation II | C++ Python | O(1) | O(1) | Medium | Simulation, Math | |
| 2080 | Range Frequency Queries | C++ Python | ctor: O(n) query: O(logn) |
O(n) | Medium | Binary Search | |
| 2102 | Sequentially Ordinal Rank Tracker | C++ Python | add: O(logn) get: O(logn) |
O(n) | Hard | Sorted List | |
| 2166 | Design Bitset | C++ Python | ctor: O(n) fix: O(1) fix: O(1) unfix: O(1) flip: O(1) all: O(1) one: O(1) count: O(1) toString: O(n) |
O(n) | Medium | ||
| 2227 | Encrypt and Decrypt Strings | C++ Python | ctor: O(m + d) encrypt: O(n) decrypt: O(n) |
O(n) | Hard | Freq Table | |
| 2241 | Design an ATM Machine | C++ Python | ctor: O(1) deposit: O(1) withdraw: O(1) |
O(1) | Medium | Greedy | |
| 2254 | Design Video Sharing Platform | C++ Python | ctor: O(1) upload: O(logn + l) remove: O(logn) like: O(1) dislike: O(1) view: O(1) getLikesAndDislikes: O(1) getViews: O(1) |
O(n * l) | Hard | 🔒 | Heap |
| 2276 | Count Integers in Intervals | C++ Python | ctor: O(1) add: O(logn), amortized Count: O(1) |
O(n) | Hard | Sorted List | |
| 2286 | Booking Concert Tickets in Groups | C++ Python | ctor: O(n) gather: O(logn) scatter: O(logn), amortized |
O(n) | Hard | Segment Tree, Binary Search | |
| 2296 | Design a Text Editor | C++ Python | ctor: O(1) addText: O(l) deleteText: O(k) cursorLeft: O(k) cursorRight: O(k) |
O(n) | Hard | Stack | |
| 2336 | Smallest Number in Infinite Set | C++ Python | ctor: O(1) popSmallest: O(logn) addBack: O(logn) |
O(n) | Medium | Heap, BST | |
| 2349 | Design a Number Container System | C++ Python | ctor: O(1) change: O(logn) find: O(1) |
O(n) | Medium | Sorted List, BST | |
| 2353 | Design a Food Rating System | C++ Python | ctor: O(nlogn) changeRating: O(logn) highestRated: O(1) |
O(n) | Medium | Sorted List, BST | |
| 2408 | Design SQL | C++ Python | ctor: O(t * max_m) insertRow: O(m) deleteRow: O(1) selectCell: O(m) |
O(d) | Medium | 🔒 | Hash Table |
| 2424 | Longest Uploaded Prefix | C++ Python | ctor: O(1) upload: O(1), amortized longest: O(1) |
O(n) | Medium | Hash Table |
| # | 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 |
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