| # | Title | Level | Time | Space | Tags | Note | Premium 🔒 |
|---|---|---|---|---|---|---|---|
| 1 | Two Sum | Easy | O(N) | O(N) | |||
| 7 | Reverse Integer | Easy | O(log x) | O(1) | Tricky | ||
| 15 | 3Sum | Medium | O(N) | O(1) | |||
| 20 | Valid Parentheses | Easy | O(N) | O(N) | String, Stack | ||
| 21 | Merge Two Sorted Lists | Easy | O(N) | O(1) | Linked List | ||
| 22 | Generate Parentheses | Medium | Complicated | Complicated | String, Backtracking | ||
| 30 | Substring with Concatenation of All Words | Hard | O(NK) | O(K) | Array, Backtracking | ||
| 39 | Combination Sum | Medium | O(N^2) | O(N) | Array, Backtracking | ||
| 46 | Permutations | Medium | O(N!) | O(N!) | Backtracking | ||
| 47 | Permutations II | Medium | O(N!) | O(N!) | Backtracking | ||
| 53 | Maximum Subarray | Easy | O(N) | O(1) | |||
| 57 | Insert Interval | Hard | O(N) | O(N) | Array, Sort, Greedy | ||
| 61 | Rotate List | Medium | O(N) | O(1) | Linked List, Two Pointers | ||
| 72 | Edit Distance | Hard | O(N * M) | O(N) | String, Dynamic Programming | ||
| 74 | Search a 2D Matrix | Medium | O(logN + logM) | O(1) | Binary Search | ||
| 78 | Subsets | Medium | O(N*2^N) | O(N*2^N) | Backtracking, Bit Manipulation | ||
| 99 | Recover Binary Search Tree | Hard | O(N) | O(N) | Tree, DFS | ||
| 100 | Same Tree | Easy | O(N) | O(H) | Tree, Pythonic | ||
| 107 | Binary Tree Level Order Traversal II | Easy | O(N) | O(N) | Tree, Breath First Search | ||
| 111 | Minimum Depth of Binary Tree | Easy | O(N) | O(H) | Tree, DFS, BFS | ||
| 114 | Flatten Binary Tree to Linked List | Medium | O(N) | O(1) | Tree, Depth First Search | ||
| 116 | Populating Next Right Pointers in Each Node | Medium | O(N) | O(N) | Tree, DFS, BFS | ||
| 119 | Pascal's Triangle II | Easy | O(k^2) | O(k) | Array | ||
| 121 | Best Time to Buy and Sell Stock | Easy | O(N) | O(1) | Dynamic Programming | ||
| 122 | Best Time to Buy and Sell Stock II | Easy | O(N) | O(1) | Array, Greedy | ||
| 125 | Valid Palindrome | Easy | O(1) | O(1) | String | ||
| 133 | Clone Graph | Medium | O(N+M) | O(N) | DFS, BFS, Graph | ||
| 134 | Gas Station | Medium | O(N) | O(N) | Dynamic Programming, Greedy | ||
| 139 | Word Break | Medium | O(N^2) | O(N) | Dynamic Programming | ||
| 142 | Linked List Cycle II | Medium | O(N) | O(1) | Linked List, Two Pointers | ||
| 143 | Reorder List | Medium | O(N) | O(1) | Linked List | ||
| 147 | Sort, Linked List | Medium | O(N^2) | O(1) | Sort, Linked List | ||
| 151 | Reverse Words in a String | Easy | O(N) | O(N) | String | ||
| 152 | Maximum Product Subarray | Medium | O(N) | O(N) | Dynamic Programming, Array | ||
| 153 | Find Minimum in Rotated Sorted Array | Medium | O(logN) | O(1) | Binary Search | ||
| 154 | Find Minimum in Rotated Sorted Array II | Hard | O(logN) | O(1) | Binary Search | ||
| 159 | Longest Substring with At Most Two Distinct Characters | Medium | O(N) | O(1) | Premium, Hash Table, Two Pointers, String, Sliding Window | ||
| 165 | Compare Version Numbers | Medium | O(N) | O(1) | String | ||
| 171 | Excel Sheet Column Number | Easy | O(N) | O(1) | String | ||
| 179 | Largest Number | Medium | O(NlogN) | O(1) | Sort | ||
| 187 | Repeated DNA Sequences | Medium | O(N-L) | O(N-L) | Hash Table, Bit Manipulation | ||
| 190 | Reverse Bits | Easy | O(1) | O(1) | Bit Manipulation | ||
| 198 | House Robber | Easy | O(N) | O(1) | Dynamic Programming | ||
| 207 | Course Schedule | Medium | O(N + E) | O(N + E) | Breath First Search, Depth First Search, Graph, Topological Sort | ||
| 208 | Implement Trie (Prefix Tree) | Medium | Varying | Varying | Design, Trie | ||
| 211 | Add and Search Word - Data structure design | Medium | O(M) | O(1) | Trie, Design | ||
| 213 | House Robber II | Medium | O(N) | O(1) | Dynamic Programming | ||
| 216 | Combination Sum III | Medium | O(N^2) | O(N^2) | Array, Backtracking | ||
| 220 | Contains Duplicate III | Medium | O(N) | O(N) | Sort, Ordered Map | ||
| 221 | Maximal Square | Medium | O(N * M) | O(1) | Array, Dynamic Programming | ||
| 222 | Count Complete Tree Nodes | Medium | O(logN * logN) | O(1) | Binary Search, Tree | ||
| 227 | Basic Calculator II | Medium | O(N) | O(N) | String, Stack | ||
| 228 | Summary Ranges | Easy | O(N) | O(1) | Array | ||
| 229 | Majority Element II | Medium | O(N) | O(1) | Array | ||
| 230 | Kth Smallest Element in a BST | Medium | O(H + k) | O(H + k) | Tree, Depth First Search | Use general formula for tree traversal | |
| 231 | Power of Two | Easy | O(1) | O(1) | Bit Manipulation | Important technique in bit manipulation | |
| 252 | Meeting Rooms | Easy | O(NlogN) | O(1) | Premium, Sort | 🔒 | |
| 253 | Meeting Rooms II | Medium | O(NlogN) | O(N) | Premium, Heap, Greedy, Sort | 🔒 | |
| 264 | Ugly Number II | Medium | O(1) | O(1) | Heap, Dynamic Programming | ||
| 270 | Closest Binary Search Tree Value | Easy | O(H) | O(1) | Premium, Binary Search, Tree | 🔒 | |
| 274 | H-Index | Medium | O(NlogN) | O(N) | Hash Table, Sort | There is a better solution | |
| 284 | Peeking Iterator | Medium | O(NlogN) | O(N) | Design | ||
| 290 | Word Pattern | Easy | O(N) | O(N) | Hash Table | ||
| 295 | Find Median from Data Stream | Hard | O(logN) | O(N) | Design, Hard, Heap | ||
| 296 | Best Meeting Point | Hard | O(M*N) | O(M+N) | Premium, Math | 🔒 | |
| 299 | Bulls and Cows | Easy | O(N) | O(N) | Hash Table | ||
| 310 | Minimum Height Trees | Medium | O(V) | O(V) | BFS, Graph | ||
| 316 | Remove Duplicate Letters | Hard | O(N) | O(1) | Greedy, Tricky, Stack | ||
| 317 | Shortest Distance from All Buildings | Hard | O(N*M) | O(N*M) | BFS, Premium | 🔒 | |
| 319 | Bulb Switcher | Medium | O(1) | O(1) | Math, Tricky | ||
| 320 | Generalized Abbreviation | Medium | O(N*2^N) | O(N) | Premium, Backtracking | 🔒 | |
| 328 | Odd Even Linked List | Medium | O(N) | O(1) | Linked List | ||
| 337 | House Robber III | Medium | O(N) | O(N) | Dynamic Programming, Tree, DFS | ||
| 338 | Counting Bits | Medium | O(N) | O(N) | Dynamic Programming, Bit Manipulation | ||
| 342 | Power of Four | Easy | O(1) | O(1) | Math, Bit Manipulation | ||
| 344 | Reverse String | Easy | O(N) | O(1) | Two Pointers, String | ||
| 346 | Moving Average from Data Stream | Easy | O(1) | O(N) | Premium, Design | 🔒 | |
| 347 | Top K Frequent Elements | Medium | O(N) | O(N) | Hash Table, Heap | ||
| 348 | Design Tic-Tac-Toe | Medium | O(1) | O(N^2) | Premium, Design | 🔒 | |
| 351 | Android Unlock Patterns | Medium | O(N!) | O(N) | Dynamic Programming, Backtracking, Premium | 🔒 | |
| 361 | Bomb Enemy | Medium | O(N*M) | O(N*M) | Premium, Dynamic Programming | 🔒 | |
| 362 | Design Hit Counter | Medium | O(1) | O(N) | Design, Premium | 🔒 | |
| 367 | Valid Perfect Square | Easy | O(logN) | O(1) | Math, Binary Search | ||
| 378 | Kth Smallest Element in a Sorted Matrix | Medium | O(N^2logK) | O(K) | Heap, Binary Search | ||
| 380 | Insert Delete GetRandom | Medium | O(1) | O(N) | Array, Hash Table, Design | ||
| 389 | Find the Difference | Medium | O(N) | O(1) | Hash Table, Bit Manipulation | ||
| 387 | First Unique Character in a String | Easy | O(N) | O(N) | |||
| 394 | Decode String | Medium | O(maxK*N) | O(N) | Stack, DFS | ||
| 395 | Longest Substring with At Least K Repeating Characters | Medium | O(NlogN) | O(N) | Divide and Conquer, Recursion, Sliding Window | ||
| 399 | Evaluate Division | Medium | O(N*M) | O(N) | Union Find, Graph | ||
| 402 | Remove K Digits | Medium | O(N) | O(N) | Greedy | ||
| 404 | Sum of Left Leaves | Easy | O(N) | O(H) | Tree | ||
| 406 | Queue Reconstruction by Height | Medium | O(N^2) | O(N) | Greedy | Clever solution | |
| 419 | Battleships in a Board | Medium | O(N*N) | O(1) | Array, Depth First Search | ||
| 425 | Word Squares | Hard | Complex | Complex | Back Tracking, Trie, Premium | 🔒 | |
| 428 | Serialize and Deserialize N-ary Tree | Hard | O(N) | O(H) | Tree, Premium | 🔒 | |
| 431 | Encode N-ary Tree to Binary Tree | Hard | O(N) | O(H) | Tree, Premium | 🔒 | |
| 435 | Non-overlapping Intervals | Medium | O(NlogN) | O(1) | Greedy | Tricky, Hard | |
| 436 | Find Right Interval | Medium | O(NlogN) | O(N) | Binary Search | Bad Description | |
| 437 | Path Sum III | Medium | O(N) | O(N) | Tree | Tricky, Hard | |
| 438 | Find All Anagrams in a String | Medium | O(N_s + N_p) | O(1) | Hash Table | ||
| 442 | Find All Duplicates in an Array | Medium | O(N) | O(1) | Array | ||
| 445 | Add Two Numbers II | Medium | O(N) | O(N) | Linked List | ||
| 449 | Serialize and Deserialize BST | Medium | O(N) | O(N) | Tree | ||
| 450 | Delete Node in a BST | Medium | O(H) | O(H) | Binary Search Tree | ||
| 451 | Sort Characters By Frequency | Medium | O(N) | O(N) | Hash Table, Sorting, Pythonic | ||
| 452 | Minimum Number of Arrows to Burst Balloons | Medium | O(NlogN) | O(1) | Sort, Greedy | ||
| 456 | 132 Pattern | Medium | O(N) | O(N) | Stack | ||
| 458 | Poor Pigs | Hard | O(1) | O(1) | Math | ||
| 462 | Minimum Moves to Equal Array Elements II | Median | O(NlogN) | O(N) | Math | ||
| 463 | Island Perimeter | Easy | O(N*M) | O(1) | Greedy | ||
| 470 | Implement Rand10() Using Rand7() | Medium | O(1) | O(1) | Math | ||
| 476 | Number Complement | Easy | O(N) | O(1) | Bit Manipulation | ||
| 495 | Teemo Attacking | Medium | O(N) | O(1) | Array | ||
| 497 | Random Point in Non-overlapping Rectangles | Medium | O(logN) | O(N) | Design, Binary Search | ||
| 510 | Inorder Successor in BST II | Medium | O(H) | O(1) | Tree, Premium | 🔒 | |
| 520 | Detect Capital | Easy | O(N) | O(1) | |||
| 525 | Contiguous Array | Medium | O(N) | O(N) | Hash Table | Very good problem | |
| 528 | Random Pick with Weight | Medium | O(N), O(logN) | O(N), O(1) | Binary Search, Random | Pythonic | |
| 532 | K-diff Pairs in an Array | Medium | O(N) | O(N) | Array, Two Pointers | ||
| 540 | Single Element in a Sorted Array | Medium | O(logN) | O(1) | Binary Search | ||
| 563 | Binary Tree Tilt | Easy | O(N) | O(H) | Tree, DFS, Recursion | ||
| 567 | Permutation in String | Medium | O(S1 + S2) | O(1) | String, Two Pointers, Sliding Window | ||
| 573 | Squirrel Simulation | Medium | O(N) | O(1) | Premium, Math | 🔒 | |
| 593 | Valid Square | Medium | O(1) | O(1) | Math | ||
| 622 | Design Circular Queue | Medium | O(1) | O(1) | Design, Queue | ||
| 624 | Maximum Distance in Arrays | Easy | O(N) | O(1) | Hash Table, Array, Premium | 🔒 | |
| 646 | Maximum Length of Pair Chain | Medium | O(NlogN) | O(N) | Greedy, Dynamic Programming | ||
| 655 | Print Binary Tree | Medium | O(N) | O(H) | Tree | ||
| 658 | Find K Closest Elements | Medium | O(logN+K) | O(K) | Tree | ||
| 662 | Maximum Width of Binary Tree | Medium | O(N) | O(N) | Tree | ||
| 673 | Number of Longest Increasing Subsequence | Medium | O(N^2) | O(N) | Dynamic Programming | ||
| 677 | Map Sum Pairs | Medium | O(K) | O(K) | Trie | ||
| 700 | Search in a Binary Search Tree | Easy | O(H) | O(1) | Tree | ||
| 701 | Insert into a Binary Search Tree | Medium | O(H) | O(1) | Tree | ||
| 702 | Search in a Sorted Array of Unknown Size | Medium | O(logN) | O(1) | Binary Search, Premium | 🔒 | |
| 705 | Design HashSet | Easy | Varies | Varies | Design HashSet | ||
| 708 | Insert into a Sorted Circular Linked List | Medium | O(N) | O(1) | Linked List, Premium | 🔒 | |
| 713 | Subarray Product Less Than K | Medium | O(N) | O(1) | Array, Two Pointers | ||
| 729 | My Calendar I | Medium | O(NlogN) | O(N) | Tree | ||
| 733 | Flood Fill | Easy | O(N) | O(N) | Depth First Search | ||
| 734 | Sentence Similarity | Easy | O(N) | O(N) | Premium, Hash Table | 🔒 | |
| 735 | Asteroid Collision | Medium | O(N) | O(N) | Stack | ||
| 737 | Sentence Similarity II | Medium | O(NlogP + P) or o(NP) | O(N) | Premium, DFS, Union Find | 🔒 | |
| 763 | Partition Labels | Medium | O(N) | O(N) | Greedy, Two Pointers | ||
| 767 | Reorganize String | Medium | O(NlogN) | O(N) | String, Heap, Greedy, Sort | ||
| 768 | Max Chunks To Make Sorted II | Hard | O(N) | O(N) | Array | ||
| 769 | Max Chunks To Make Sorted | Medium | O(N) | O(1) | Array | ||
| 787 | Cheapest Flights Within K Stops | Medium | Complex | Complex | Dijkstra's Algorithm, Graph | Quite hard | |
| 791 | Custom Sort String | Medium | O(N) | O(N) | String | ||
| 794 | Valid Tic-Tac-Toe State | Medium | O(1) | O(1) | Array, String | ||
| 797 | All Paths From Source to Target | Medium | O(2^N * N) | O(2^N * N) | Backtracking, Depth First Search | ||
| 799 | Champagne Tower | Medium | O(R^2) | O(R^2) | Dynamic Programming | ||
| 820 | Short Encoding of Words | Medium | O(N*M) | O(N*M) | Trie | ||
| 825 | Friends Of Appropriate Ages | Medium | O(N) | O(1) | Array | ||
| 830 | Positions of Large Groups | Easy | O(N) | O(1) | |||
| 833 | Find And Replace in String | Medium | O(N) | O(N) | String | ||
| 835 | Image Overlap | Medium | O(N^2) | O(N) | |||
| 838 | Push Dominoes | Medium | O(N) | O(N) | |||
| 845 | Longest Mountain in Array | Medium | O(N) | O(1) | Two Pointers | ||
| 846 | Hand of Straights | Medium | O(MlogM+NW) | O(N) | Ordered Map | ||
| 849 | Maximize Distance to Closest Person | Medium | O(N) | O(1) | Array | ||
| 851 | Loud and Rich | Medium | O(N^2) | O(N^2) | DFS | ||
| 853 | Car Fleet | Medium | O(NlogN) | O(N) | Sort | ||
| 858 | Mirror Reflection | Medium | O(logN) | O(1) | Math | ||
| 859 | Buddy Strings | Easy | O(N) | O(1) | String | ||
| 875 | Koko Eating Bananas | Medium | O(NlogN) | O(1) | Binary Search | ||
| 886 | Possible Bipartition | Medium | O(N + E) | O(N + E) | Depth First Search | Good problem | |
| 901 | Online Stock Span | Medium | O(1) | O(N) | Monotonic Stack | ||
| 902 | Numbers At Most N Given Digit Set | Hard | O(LogN) | O(1) | Math, Dynamic Programming | ||
| 905 | Sort Array By Parity | Easy | O(N) | O(1) | Array | ||
| 918 | Maximum Sum Circular Subarray | Medium | O(N) | O(1) | Array, Dynamic Programming | ||
| 926 | Flip String to Monotone Increasing | Medium | O(N) | O(N) | Array | ||
| 930 | Binary Subarrays With Sum | Medium | O(N) | O(N) | Hash Table, Two Pointers | ||
| 933 | Number of Recent Calls | Easy | O(1) | O(1) | Queue | ||
| 935 | Knight Dialer | Medium | O(N) | O(1) | Dynamic Programming | ||
| 946 | Validate Stack Sequences | Medium | O(N) | O(N) | Stack | ||
| 948 | Bag of Tokens | Medium | O(NlogN) | O(N) | Greedy | ||
| 957 | Prison Cells After N Days | Medium | O(1) | O(1) | Has Table | ||
| 967 | Numbers With Same Consecutive Differences | Medium | O(N*2^N) | O(2^N) | DFS | ||
| 969 | Pancake Sorting | Medium | O(N^2) | O(N) | Array | ||
| 973 | K Closest Points to Origin | Medium | O(N log(K)) | O(K) | Divide and Conquer, Heap, Sort | ||
| 976 | Largest Perimeter Triangle | Medium | O(NlogN) | O(N) | Math, Sort | ||
| 979 | Distribute Coins in Binary Tree | Medium | O(N) | O(H) | Tree, DFS | ||
| 980 | Unique Paths III | Medium | O(2^N) | O(N) | Backtracking, DFS | ||
| 983 | Minimum Cost For Tickets | Medium | O(365) | O(365) | LRU Cache, Dynamic Programming | ||
| 986 | Interval List Intersections | Medium | O(N + M) | O(1) | Two Pointers | ||
| 987 | Vertical Order Traversal of a Binary Tree | Medium | O(NlogN) | O(N) | Hash Table, Tree | ||
| 993 | Cousins in Binary Tree | Easy | O(N) | O(H) | Trees, Recursion | ||
| 994 | Rotting Oranges | Medium | O(N^2) | O(N) | Trees, Recursion | ||
| 1004 | Max Consecutive Ones III | Medium | O(N) | O(1) | Sliding Window, Two Pointers | ||
| 1007 | Minimum Domino Rotations For Equal Row | Medium | O(N) | O(1) | Array, Greedy | ||
| 1015 | Smallest Integer Divisible by K | Medium | O(K) | O(K) | Math | ||
| 1022 | Sum of Root To Leaf Binary Numbers | Easy | O(N) | O(H) | Tree | ||
| 1026 | Maximum Difference Between Node and Ancestor | Medium | O(N) | O(H) | Tree, DFS | ||
| 1029 | Two City Scheduling | Easy | O(NlogN) | O(N) | Greedy | Good Problem | |
| 1032 | Stream of Characters | Hard | O(M) | O(M) | Trie | ||
| 1035 | Uncrossed Lines | Medium | O(N^2) | O(N) | Array, Dynamic Programming | ||
| 1060 | Missing Element in Sorted Array | Medium | O(logN) | O(1) | Binary Search, Premium | 🔒 | |
| 1061 | Lexicographically Smallest Equivalent String | Medium | O(N) | O(N) | DFS, Union Find, Premium | 🔒 | |
| 1094 | Car Pooling | Medium | O(N) | O(1) | Car Pooling | ||
| 1162 | As Far from Land as Possible | Medium | O(N*M) | O(N*M) | Graph, BFS | ||
| 1217 | Minimum Cost to Move Chips to The Same Position | Easy | O(N) | O(1) | Math, Greedy, Array | ||
| 1232 | Check If It Is a Straight Line | Easy | O(N) | O(1) | Math, Pythonic, Geometry | ||
| 1249 | Minimum Remove to Make Valid Parentheses | Medium | O(N) | O(N) | Stack, String | ||
| 1277 | Count Square Submatrices with All Ones | Medium | O(N * M) | O(1) | Array, Dynamic Programming | ||
| 1283 | Find the Smallest Divisor Given a Threshold | Medium | O(NlogNmax) | O(1) | Binary Search | ||
| 1288 | Remove Covered Intervals | Medium | O(N) | O(1) | Greedy, Sort, Line Sweep | ||
| 1290 | Convert Binary Number in a Linked List to Integer | Easy | O(N) | O(1) | Linked List, Bit Manipulation | ||
| 1291 | Sequential Digits | Medium | O(N) | O(N) | Backtracking | ||
| 1305 | All Elements in Two Binary Search Trees | Medium | O(N) | O(N) | Sort, Tree | ||
| 1344 | Angle Between Hands of a Clock | Medium | O(1) | O(1) | Math | ||
| 1375 | Bulb Switcher III | Medium | O(N) | O(1) | Array | ||
| 1426 | Counting Elements | Easy | O(N) | O(N) | Array, Premium | 🔒 | |
| 1427 | Perform String Shifts | Easy | O(N + S) | O(1) | 🔒 | ||
| 1441 | Build an Array With Stack Operations | Easy | O(N) | O(N) | Pythonic | ||
| 1442 | Count Triplets That Can Form Two Arrays of Equal XOR | Medium | O(N) | O(N) | Array, Math, Bit Manipulation | ||
| 1443 | Minimum Time to Collect All Apples in a Tree | Medium | O(E) | O(E) | Tree, Depth First Search | ||
| 1446 | Consecutive Characters | Easy | O(N) | O(1) | String | ||
| 1447 | Simplified Fractions | Medium | Varying | Varying | |||
| 1448 | Count Good Nodes in Binary Tree | Medium | O(N) | O(H) | Tree, Depth First Search | ||
| 1450 | Number of Students Doing Homework at a Given Time | Easy | O(N) | O(1) | |||
| 1451 | Rearrange Words in a Sentence | Medium | O(N * logN) | O(1) | String, Sort | ||
| 1452 | People Whose List of Favorite Companies Is Not a Subset of Another List | Medium | O(N^2) | O(N) | String, Sort | There is a better solution | |
| 1455 | Check If a Word Occurs As a Prefix of Any Word in a Sentence | Medium | O(N) | O(1) | String, Pythonic | ||
| 1456 | Maximum Number of Vowels in a Substring of Given Length | Medium | O(N) | O(1) | String, Sliding Window | ||
| 1457 | Pseudo-Palindromic Paths in a Binary Tree | Medium | O(N) | O(H) | Bit Manipulation, Tree, Depth First Search | ||
| 1460 | Make Two Arrays Equal by Reversing Sub-arrays | Easy | O(N) | O(1) | Array | ||
| 1464 | Maximum Product of Two Elements in an Array | Easy | O(N) | O(1) | Array | ||
| 1466 | Reorder Routes to Make All Paths Lead to the City Zero | Medium | O(|V|) | O(|V|) | Tree, Depth First Search | ||
| 1470 | Shuffle the Array | Easy | O(N) | O(N) | Array | There is a better solution | |
| 1471 | The k Strongest Values in an Array | Medium | O(NlogN) | O(N) | Array, Sort | There is a better solution | |
| 1472 | Design Browser History | Medium | O(1) | O(1) | Design | ||
| 1474 | Delete N Nodes After M Nodes of a Linked List | Easy | O(N) | O(1) | Linked List, Premium | 🔒 | |
| 1475 | Final Prices With a Special Discount in a Shop | Easy | O(N) | O(1) | Monotonic Stack | ||
| 1476 | Subrectangle Queries | Easy | Varies | Varies | Design | ||
| 1480 | Running Sum of 1d Array | Easy | O(N) | O(1) | |||
| 1481 | Least Number of Unique Integers after K Removals | Medium | O(NlogN) | O(N) | Array, Sort | ||
| 1482 | Minimum Number of Days to Make m Bouquets | Medium | O(NlogN) | O(N) | Array, Binary Search | ||
| 1486 | XOR Operation in an Array | Easy | O(1) | O(1) | Bit Manipulation | ||
| 1491 | Average Salary Excluding the Minimum and Maximum Salary | Easy | O(N) | O(1) | |||
| 1492 | The kth Factor of n | Medium | O(logN) | O(logN) | Math, Tricky | ||
| 1493 | Longest Subarray of 1's After Deleting One Element | Medium | O(N) | O(1) | Array | ||
| 1496 | Path Crossing | Easy | O(N) | O(N) | String | ||
| 1502 | Can Make Arithmetic Progression From Sequence | Easy | O(NlogN) | O(1) | Array | ||
| 1507 | Reformat Date | Easy | O(1) | O(1) | String | ||
| 1508 | Range Sum of Sorted Subarray Sums | Medium | O(N^2logN) | O(N^2) | |||
| 1509 | Minimum Difference Between Largest and Smallest Value in Three Moves | Medium | O(NlogN) | O(1) | |||
| 1510 | Stone Game IV | Hard | O(N*N^0.5) | O(N) | Dynamic Programming | ||
| 1512 | Number of Good Pairs | Easy | O(N) | O(N) | |||
| 1513 | Number of Substrings With Only 1s | Medium | O(N) | O(N) | String, Math | ||
| 1518 | Water Bottles | Easy | O(1) | O(1) | Greedy, Simulation | ||
| 1523 | Count Odd Numbers in an Interval Range | Easy | O(1) | O(1) | Math | ||
| 1524 | Number of Sub-arrays With Odd Sum | Medium | O(N) | O(1) | Array, Math, Dynamic Programming | ||
| 1525 | Number of Good Ways to Split a String | Medium | O(N) | O(N) | String | ||
| 1528 | Shuffle String | Easy | O(N) | O(N) | String | ||
| 1529 | Bulb Switcher IV | Medium | O(N) | O(1) | String | ||
| 1530 | Number of Good Leaf Nodes Pairs | Medium | O(N^2logN) | O(N) | Tree, Depth First Search | ||
| 1533 | Find the Index of the Large Integer | Medium | O(logN) | O(1) | Premium, Binary Search | 🔒 | |
| 1535 | Find the Winner of an Array Game | Medium | O(N) | O(1) | Array | ||
| 1539 | Kth Missing Positive Number | Easy | O(logN) | O(1) | Binary Search | ||
| 1544 | Make The String Great | Easy | O(N) | O(N) | String, Stack | ||
| 1545 | Find Kth Bit in Nth Binary String | Medium | O(N^2) | O(N^2) | String | Not Optimal | |
| 1550 | Three Consecutive Odds | Easy | O(N) | O(1) | Array | ||
| 1551 | Minimum Operations to Make Array Equal | Medium | O(1) | O(1) | Math | ||
| 1552 | Magnetic Force Between Two Balls | Medium | O(NlogN) | O(1) | Binary Search | Template for Binary Search | |
| 1556 | Thousand Separator | Easy | O(N) | O(N) | String | ||
| 1557 | Minimum Number of Vertices to Reach All Nodes | Medium | O(N) | O(N) | Graph | ||
| 1558 | Minimum Numbers of Function Calls to Make Target Array | Medium | O(NlogK) | O(N) | Greedy, Simulation | ||
| 1560 | Most Visited Sector in a Circular Track | Easy | O(N) | O(1) | Array | ||
| 1561 | Maximum Number of Coins You Can Get | Medium | O(N) | O(1) | Sort | ||
| 1564 | Put Boxes Into the Warehouse I | Medium | O(NlogN) | O(N) | Greedy | 🔒 | |
| 1566 | Detect Pattern of Length M Repeated K or More Times | Easy | O(N) | O(1) | Array | ||
| 1572 | Matrix Diagonal Sum | Easy | O(N) | O(1) | Array | ||
| 1573 | Number of Ways to Split a String | Medium | O(N) | O(N) | String | ||
| 1576 | Replace All ?'s to Avoid Consecutive Repeating Characters | Easy | O(N) | O(N) | String | ||
| 1578 | Minimum Deletion Cost to Avoid Repeating Letters | Medium | O(N) | O(1) | Greedy | ||
| 1580 | Put Boxes Into the Warehouse II | Medium | O(NlogN) | O(N) | Greedy | 🔒 | |
| 1582 | Special Positions in a Binary Matrix | Easy | O(N) | O(N) | Array | ||
| 1583 | Count Unhappy Friends | Medium | O(N^2) | O(N^2) | Array | ||
| 1588 | Sum of All Odd Length Subarrays | Easy | O(N) | O(1) | Array | ||
| 1592 | Rearrange Spaces Between Words | Easy | O(N) | O(N) | String | ||
| 1598 | Crawler Log Folder | Easy | O(N) | O(1) | Stack | ||
| 1600 | Throne Inheritance | Medium | O(N) | O(N) | Tree, Design | ||
| 1602 | Find Nearest Right Node in Binary Tree | Medium | O(N) | O(N) | Premium, Tree, BFS | 🔒 | |
| 1604 | Alert Using Same Key-Card Three or More Times in a One Hour Period | Medium | O(NlogN) | O(N) | String, Ordered Map | ||
| 1605 | Find Valid Matrix Given Row and Column Sums | Medium | O(NM) | O(NM) | Greedy | ||
| 1608 | Special Array With X Elements Greater Than or Equal X | Easy | O(NlogN) | O(N) | Binary Search, Array | ||
| 1609 | Even Odd Tree | Easy | O(N) | O(N) | Tree | ||
| 1614 | Maximum Nesting Depth of the Parentheses | Easy | O(N) | O(1) | String | ||
| 1615 | Maximal Network Rank | Medium | O(N) | O(1) | Graph | ||
| 1618 | Maximum Font to Fit a Sentence in a Screen | Medium | O(logN) | O(1) | Premium, String, Binary Search | 🔒 | |
| 1624 | Largest Substring Between Two Equal Characters | Easy | O(N) | O(1) | String | ||
| 1629 | Slowest Key | Easy | O(N) | O(1) | String | ||
| 1634 | Add Two Polynomials Represented as Linked Lists | Medium | O(N) | O(1) | Premium, Linked List | 🔒 | |
| 1639 | Number of Ways to Form a Target String Given a Dictionary | Hard | O(N*M) | O(N*M) | Dynamic Programming | ||
| 1640 | Check Array Formation Through Concatenation | Medium | O(N) | O(N) | Array | ||
| 1641 | Count Sorted Vowel Strings | Medium | O(N) | O(1) | Dynamic Programming, Math, Backtracking | ||
| 1642 | Furthest Building You Can Reach | Medium | O(NlogN) | O(N) | Binary Search, Heap | ||
| 1644 | Lowest Common Ancestor of a Binary Tree II | Medium | O(N) | O(H) | Premium, Tree | 🔒 | |
| 1646 | Get Maximum in Generated Array | Easy | O(N) | O(N) | Array | ||
| 1647 | Minimum Deletions to Make Character Frequencies Unique | Medium | O(1) | O(1) | Greedy, Sort | ||
| 1650 | Lowest Common Ancestor of a Binary Tree III | Medium | O(H) | O(1) | Premium, Tree | 🔒 | |
| 1652 | Defuse the Bomb | Medium | O(N) | O(N) | Array | ||
For premium problems, question description are available as screenshots here
https://leetcode.com/jummyegg/
- Important and Useful links from all over the LeetCode
- Graph: https://leetcode.com/discuss/general-discussion/655708/Graph-For-Beginners-Problems-or-Pattern-or-Sample-Solutions
- Sliding Windows: https://leetcode.com/discuss/general-discussion/657507/Sliding-Window-for-Beginners-Problems-or-Template-or-Sample-Solutions
- Trie: https://leetcode.com/discuss/general-discussion/680706/Article-on-Trie.-General-Template-and-List-of-problems.
- https://leetcode.com/discuss/general-discussion/662866/dp-for-beginners-problems-patterns-sample-solutions
- https://leetcode.com/discuss/interview-question/491522/dynamic-programming-questions-thread
- https://leetcode.com/discuss/general-discussion/458695/Dynamic-Programming-Patterns
- https://leetcode.com/discuss/general-discussion/868902/dynamic-programming