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README_EN.md 398.14 KB
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ylb 提交于 2021-05-17 10:38 . feat: add lc problems: No.1858-1866

LeetCode

中文文档

Solutions

Press Control+F(or Command+F on the Mac) to search anything you want.

# Solution Tags Difficulty Remark
0001 Two Sum Array,Hash Table Easy
0002 Add Two Numbers Recursion,Linked List,Math Medium
0003 Longest Substring Without Repeating Characters Hash Table,Two Pointers,String,Sliding Window Medium
0004 Median of Two Sorted Arrays Array,Binary Search,Divide and Conquer Hard
0005 Longest Palindromic Substring String,Dynamic Programming Medium
0006 ZigZag Conversion String Medium
0007 Reverse Integer Math Easy
0008 String to Integer (atoi) Math,String Medium
0009 Palindrome Number Math Easy
0010 Regular Expression Matching String,Dynamic Programming,Backtracking Hard
0011 Container With Most Water Array,Two Pointers Medium
0012 Integer to Roman Math,String Medium
0013 Roman to Integer Math,String Easy
0014 Longest Common Prefix String Easy
0015 3Sum Array,Two Pointers Medium
0016 3Sum Closest Array,Two Pointers Medium
0017 Letter Combinations of a Phone Number Depth-first Search,Recursion,String,Backtracking Medium
0018 4Sum Array,Hash Table,Two Pointers Medium
0019 Remove Nth Node From End of List Linked List,Two Pointers Medium
0020 Valid Parentheses Stack,String Easy
0021 Merge Two Sorted Lists Recursion,Linked List Easy
0022 Generate Parentheses String,Backtracking Medium
0023 Merge k Sorted Lists Heap,Linked List,Divide and Conquer Hard
0024 Swap Nodes in Pairs Recursion,Linked List Medium
0025 Reverse Nodes in k-Group Linked List Hard
0026 Remove Duplicates from Sorted Array Array,Two Pointers Easy
0027 Remove Element Array,Two Pointers Easy
0028 Implement strStr() Two Pointers,String Easy
0029 Divide Two Integers Math,Binary Search Medium
0030 Substring with Concatenation of All Words Hash Table,Two Pointers,String Hard
0031 Next Permutation Array Medium
0032 Longest Valid Parentheses String,Dynamic Programming Hard
0033 Search in Rotated Sorted Array Array,Binary Search Medium
0034 Find First and Last Position of Element in Sorted Array Array,Binary Search Medium
0035 Search Insert Position Array,Binary Search Easy
0036 Valid Sudoku Hash Table Medium
0037 Sudoku Solver Hash Table,Backtracking Hard
0038 Count and Say String Easy
0039 Combination Sum Array,Backtracking Medium
0040 Combination Sum II Array,Backtracking Medium
0041 First Missing Positive Array Hard
0042 Trapping Rain Water Stack,Array,Two Pointers,Dynamic Programming Hard
0043 Multiply Strings Math,String Medium
0044 Wildcard Matching Greedy,String,Dynamic Programming,Backtracking Hard
0045 Jump Game II Greedy,Array Medium
0046 Permutations Backtracking Medium
0047 Permutations II Backtracking Medium
0048 Rotate Image Array Medium
0049 Group Anagrams Hash Table,String Medium
0050 Pow(x, n) Math,Binary Search Medium
0051 N-Queens Backtracking Hard
0052 N-Queens II Backtracking Hard
0053 Maximum Subarray Array,Divide and Conquer,Dynamic Programming Easy
0054 Spiral Matrix Array Medium
0055 Jump Game Greedy,Array Medium
0056 Merge Intervals Sort,Array Medium
0057 Insert Interval Sort,Array Medium
0058 Length of Last Word String Easy
0059 Spiral Matrix II Array Medium
0060 Permutation Sequence Math,Backtracking Hard
0061 Rotate List Linked List,Two Pointers Medium
0062 Unique Paths Array,Dynamic Programming Medium
0063 Unique Paths II Array,Dynamic Programming Medium
0064 Minimum Path Sum Array,Dynamic Programming Medium
0065 Valid Number Math,String Hard
0066 Plus One Array Easy
0067 Add Binary Math,String Easy
0068 Text Justification String Hard
0069 Sqrt(x) Math,Binary Search Easy
0070 Climbing Stairs Dynamic Programming Easy
0071 Simplify Path Stack,String Medium
0072 Edit Distance String,Dynamic Programming Hard
0073 Set Matrix Zeroes Array Medium
0074 Search a 2D Matrix Array,Binary Search Medium
0075 Sort Colors Sort,Array,Two Pointers Medium
0076 Minimum Window Substring Hash Table,Two Pointers,String,Sliding Window Hard
0077 Combinations Backtracking Medium
0078 Subsets Bit Manipulation,Array,Backtracking Medium
0079 Word Search Array,Backtracking Medium
0080 Remove Duplicates from Sorted Array II Array,Two Pointers Medium
0081 Search in Rotated Sorted Array II Array,Binary Search Medium
0082 Remove Duplicates from Sorted List II Linked List Medium
0083 Remove Duplicates from Sorted List Linked List Easy
0084 Largest Rectangle in Histogram Stack,Array Hard
0085 Maximal Rectangle Stack,Array,Hash Table,Dynamic Programming Hard
0086 Partition List Linked List,Two Pointers Medium
0087 Scramble String String,Dynamic Programming Hard
0088 Merge Sorted Array Array,Two Pointers Easy
0089 Gray Code Backtracking Medium
0090 Subsets II Array,Backtracking Medium
0091 Decode Ways String,Dynamic Programming Medium
0092 Reverse Linked List II Linked List Medium
0093 Restore IP Addresses String,Backtracking Medium
0094 Binary Tree Inorder Traversal Stack,Tree,Hash Table Easy
0095 Unique Binary Search Trees II Tree,Dynamic Programming Medium
0096 Unique Binary Search Trees Tree,Dynamic Programming Medium
0097 Interleaving String String,Dynamic Programming Medium
0098 Validate Binary Search Tree Tree,Depth-first Search,Recursion Medium
0099 Recover Binary Search Tree Tree,Depth-first Search Hard
0100 Same Tree Tree,Depth-first Search Easy
0101 Symmetric Tree Tree,Depth-first Search,Breadth-first Search Easy
0102 Binary Tree Level Order Traversal Tree,Breadth-first Search Medium
0103 Binary Tree Zigzag Level Order Traversal Stack,Tree,Breadth-first Search Medium
0104 Maximum Depth of Binary Tree Tree,Depth-first Search,Recursion Easy
0105 Construct Binary Tree from Preorder and Inorder Traversal Tree,Depth-first Search,Array Medium
0106 Construct Binary Tree from Inorder and Postorder Traversal Tree,Depth-first Search,Array Medium
0107 Binary Tree Level Order Traversal II Tree,Breadth-first Search Medium
0108 Convert Sorted Array to Binary Search Tree Tree,Depth-first Search Easy
0109 Convert Sorted List to Binary Search Tree Depth-first Search,Linked List Medium
0110 Balanced Binary Tree Tree,Depth-first Search,Recursion Easy
0111 Minimum Depth of Binary Tree Tree,Depth-first Search,Breadth-first Search Easy
0112 Path Sum Tree,Depth-first Search Easy
0113 Path Sum II Tree,Depth-first Search Medium
0114 Flatten Binary Tree to Linked List Tree,Depth-first Search Medium
0115 Distinct Subsequences String,Dynamic Programming Hard
0116 Populating Next Right Pointers in Each Node Tree,Depth-first Search,Breadth-first Search Medium
0117 Populating Next Right Pointers in Each Node II Tree,Depth-first Search Medium
0118 Pascal's Triangle Array Easy
0119 Pascal's Triangle II Array Easy
0120 Triangle Array,Dynamic Programming Medium
0121 Best Time to Buy and Sell Stock Array,Dynamic Programming Easy
0122 Best Time to Buy and Sell Stock II Greedy,Array Easy
0123 Best Time to Buy and Sell Stock III Array,Dynamic Programming Hard
0124 Binary Tree Maximum Path Sum Tree,Depth-first Search,Recursion Hard
0125 Valid Palindrome Two Pointers,String Easy
0126 Word Ladder II Breadth-first Search,Array,String,Backtracking Hard
0127 Word Ladder Breadth-first Search Hard
0128 Longest Consecutive Sequence Union Find,Array Hard
0129 Sum Root to Leaf Numbers Tree,Depth-first Search Medium
0130 Surrounded Regions Depth-first Search,Breadth-first Search,Union Find Medium
0131 Palindrome Partitioning Depth-first Search,Dynamic Programming,Backtracking Medium
0132 Palindrome Partitioning II Dynamic Programming Hard
0133 Clone Graph Depth-first Search,Breadth-first Search,Graph Medium
0134 Gas Station Greedy Medium
0135 Candy Greedy Hard
0136 Single Number Bit Manipulation,Hash Table Easy
0137 Single Number II Bit Manipulation Medium
0138 Copy List with Random Pointer Hash Table,Linked List Medium
0139 Word Break Dynamic Programming Medium
0140 Word Break II Dynamic Programming,Backtracking Hard
0141 Linked List Cycle Linked List,Two Pointers Easy
0142 Linked List Cycle II Linked List,Two Pointers Medium
0143 Reorder List Linked List Medium
0144 Binary Tree Preorder Traversal Stack,Tree Medium
0145 Binary Tree Postorder Traversal Stack,Tree Easy
0146 LRU Cache Design Medium
0147 Insertion Sort List Sort,Linked List Medium
0148 Sort List Sort,Linked List Medium
0149 Max Points on a Line Hash Table,Math Hard
0150 Evaluate Reverse Polish Notation Stack Medium
0151 Reverse Words in a String String Medium
0152 Maximum Product Subarray Array,Dynamic Programming Medium
0153 Find Minimum in Rotated Sorted Array Array,Binary Search Medium
0154 Find Minimum in Rotated Sorted Array II Array,Binary Search Hard
0155 Min Stack Stack,Design Easy
0156 Binary Tree Upside Down Tree Medium 🔒
0157 Read N Characters Given Read4 String Easy 🔒
0158 Read N Characters Given Read4 II - Call multiple times String Hard 🔒
0159 Longest Substring with At Most Two Distinct Characters Hash Table,Two Pointers,String,Sliding Window Medium 🔒
0160 Intersection of Two Linked Lists Linked List Easy
0161 One Edit Distance String Medium 🔒
0162 Find Peak Element Array,Binary Search Medium
0163 Missing Ranges Array Easy 🔒
0164 Maximum Gap Sort Hard
0165 Compare Version Numbers String Medium
0166 Fraction to Recurring Decimal Hash Table,Math Medium
0167 Two Sum II - Input array is sorted Array,Two Pointers,Binary Search Easy
0168 Excel Sheet Column Title Math Easy
0169 Majority Element Bit Manipulation,Array,Divide and Conquer Easy
0170 Two Sum III - Data structure design Design,Hash Table Easy 🔒
0171 Excel Sheet Column Number Math Easy
0172 Factorial Trailing Zeroes Math Easy
0173 Binary Search Tree Iterator Stack,Tree,Design Medium
0174 Dungeon Game Binary Search,Dynamic Programming Hard
0175 Combine Two Tables Easy
0176 Second Highest Salary Easy
0177 Nth Highest Salary Medium
0178 Rank Scores Medium
0179 Largest Number Sort Medium
0180 Consecutive Numbers Medium
0181 Employees Earning More Than Their Managers Easy
0182 Duplicate Emails Easy
0183 Customers Who Never Order Easy
0184 Department Highest Salary Medium
0185 Department Top Three Salaries Hard
0186 Reverse Words in a String II String Medium 🔒
0187 Repeated DNA Sequences Bit Manipulation,Hash Table Medium
0188 Best Time to Buy and Sell Stock IV Dynamic Programming Hard
0189 Rotate Array Array Medium
0190 Reverse Bits Bit Manipulation Easy
0191 Number of 1 Bits Bit Manipulation Easy
0192 Word Frequency Medium
0193 Valid Phone Numbers Easy
0194 Transpose File Medium
0195 Tenth Line Easy
0196 Delete Duplicate Emails Easy
0197 Rising Temperature Easy
0198 House Robber Dynamic Programming Medium
0199 Binary Tree Right Side View Tree,Depth-first Search,Breadth-first Search,Recursion,Queue Medium
0200 Number of Islands Depth-first Search,Breadth-first Search,Union Find Medium
0201 Bitwise AND of Numbers Range Bit Manipulation Medium
0202 Happy Number Hash Table,Math Easy
0203 Remove Linked List Elements Linked List Easy
0204 Count Primes Hash Table,Math Easy
0205 Isomorphic Strings Hash Table Easy
0206 Reverse Linked List Linked List Easy
0207 Course Schedule Depth-first Search,Breadth-first Search,Graph,Topological Sort Medium
0208 Implement Trie (Prefix Tree) Design,Trie Medium
0209 Minimum Size Subarray Sum Array,Two Pointers,Binary Search Medium
0210 Course Schedule II Depth-first Search,Breadth-first Search,Graph,Topological Sort Medium
0211 Design Add and Search Words Data Structure Depth-first Search,Design,Trie,Backtracking Medium
0212 Word Search II Trie,Backtracking Hard
0213 House Robber II Dynamic Programming Medium
0214 Shortest Palindrome String Hard
0215 Kth Largest Element in an Array Heap,Divide and Conquer Medium
0216 Combination Sum III Array,Backtracking Medium
0217 Contains Duplicate Array,Hash Table Easy
0218 The Skyline Problem Heap,Binary Indexed Tree,Segment Tree,Divide and Conquer,Line Sweep Hard
0219 Contains Duplicate II Array,Hash Table Easy
0220 Contains Duplicate III Sort,Ordered Map Medium
0221 Maximal Square Dynamic Programming Medium
0222 Count Complete Tree Nodes Tree,Binary Search Medium
0223 Rectangle Area Math Medium
0224 Basic Calculator Stack,Math Hard
0225 Implement Stack using Queues Stack,Design Easy
0226 Invert Binary Tree Tree Easy
0227 Basic Calculator II Stack,String Medium
0228 Summary Ranges Array Easy
0229 Majority Element II Array Medium
0230 Kth Smallest Element in a BST Tree,Binary Search Medium
0231 Power of Two Bit Manipulation,Math Easy
0232 Implement Queue using Stacks Stack,Design Easy
0233 Number of Digit One Math Hard
0234 Palindrome Linked List Linked List,Two Pointers Easy
0235 Lowest Common Ancestor of a Binary Search Tree Tree Easy
0236 Lowest Common Ancestor of a Binary Tree Tree Medium
0237 Delete Node in a Linked List Linked List Easy
0238 Product of Array Except Self Array Medium
0239 Sliding Window Maximum Heap,Sliding Window Hard
0240 Search a 2D Matrix II Binary Search,Divide and Conquer Medium
0241 Different Ways to Add Parentheses Divide and Conquer Medium
0242 Valid Anagram Sort,Hash Table Easy
0243 Shortest Word Distance Array Easy 🔒
0244 Shortest Word Distance II Design,Hash Table Medium 🔒
0245 Shortest Word Distance III Array Medium 🔒
0246 Strobogrammatic Number Hash Table,Math Easy 🔒
0247 Strobogrammatic Number II Recursion,Math Medium 🔒
0248 Strobogrammatic Number III Recursion,Math Hard 🔒
0249 Group Shifted Strings Hash Table,String Medium 🔒
0250 Count Univalue Subtrees Tree Medium 🔒
0251 Flatten 2D Vector Design Medium 🔒
0252 Meeting Rooms Sort Easy 🔒
0253 Meeting Rooms II Heap,Greedy,Sort Medium 🔒
0254 Factor Combinations Backtracking Medium 🔒
0255 Verify Preorder Sequence in Binary Search Tree Stack,Tree Medium 🔒
0256 Paint House Dynamic Programming Medium 🔒
0257 Binary Tree Paths Tree,Depth-first Search Easy
0258 Add Digits Math Easy
0259 3Sum Smaller Array,Two Pointers Medium 🔒
0260 Single Number III Bit Manipulation Medium
0261 Graph Valid Tree Depth-first Search,Breadth-first Search,Union Find,Graph Medium 🔒
0262 Trips and Users Hard
0263 Ugly Number Math Easy
0264 Ugly Number II Heap,Math,Dynamic Programming Medium
0265 Paint House II Dynamic Programming Hard 🔒
0266 Palindrome Permutation Hash Table Easy 🔒
0267 Palindrome Permutation II Backtracking Medium 🔒
0268 Missing Number Bit Manipulation,Array,Math Easy
0269 Alien Dictionary Graph,Topological Sort Hard 🔒
0270 Closest Binary Search Tree Value Tree,Binary Search Easy 🔒
0271 Encode and Decode Strings String Medium 🔒
0272 Closest Binary Search Tree Value II Stack,Tree Hard 🔒
0273 Integer to English Words Math,String Hard
0274 H-Index Sort,Hash Table Medium
0275 H-Index II Binary Search Medium
0276 Paint Fence Dynamic Programming Medium 🔒
0277 Find the Celebrity Array Medium 🔒
0278 First Bad Version Binary Search Easy
0279 Perfect Squares Breadth-first Search,Math,Dynamic Programming Medium
0280 Wiggle Sort Sort,Array Medium 🔒
0281 Zigzag Iterator Design Medium 🔒
0282 Expression Add Operators Divide and Conquer Hard
0283 Move Zeroes Array,Two Pointers Easy
0284 Peeking Iterator Design Medium
0285 Inorder Successor in BST Tree Medium 🔒
0286 Walls and Gates Breadth-first Search Medium 🔒
0287 Find the Duplicate Number Array,Two Pointers,Binary Search Medium
0288 Unique Word Abbreviation Design,Hash Table Medium 🔒
0289 Game of Life Array Medium
0290 Word Pattern Hash Table Easy
0291 Word Pattern II Backtracking Medium 🔒
0292 Nim Game Brainteaser,Minimax Easy
0293 Flip Game String Easy 🔒
0294 Flip Game II Minimax,Backtracking Medium 🔒
0295 Find Median from Data Stream Heap,Design Hard
0296 Best Meeting Point Sort,Math Hard 🔒
0297 Serialize and Deserialize Binary Tree Tree,Design Hard
0298 Binary Tree Longest Consecutive Sequence Tree Medium 🔒
0299 Bulls and Cows Hash Table Medium
0300 Longest Increasing Subsequence Binary Search,Dynamic Programming Medium
0301 Remove Invalid Parentheses Depth-first Search,Breadth-first Search Hard
0302 Smallest Rectangle Enclosing Black Pixels Binary Search Hard 🔒
0303 Range Sum Query - Immutable Dynamic Programming Easy
0304 Range Sum Query 2D - Immutable Dynamic Programming Medium
0305 Number of Islands II Union Find Hard 🔒
0306 Additive Number Backtracking Medium
0307 Range Sum Query - Mutable Binary Indexed Tree,Segment Tree Medium
0308 Range Sum Query 2D - Mutable Binary Indexed Tree,Segment Tree Hard 🔒
0309 Best Time to Buy and Sell Stock with Cooldown Dynamic Programming Medium
0310 Minimum Height Trees Breadth-first Search,Graph Medium
0311 Sparse Matrix Multiplication Hash Table Medium 🔒
0312 Burst Balloons Divide and Conquer,Dynamic Programming Hard
0313 Super Ugly Number Heap,Math Medium
0314 Binary Tree Vertical Order Traversal Depth-first Search,Breadth-first Search Medium 🔒
0315 Count of Smaller Numbers After Self Sort,Binary Indexed Tree,Segment Tree,Binary Search,Divide and Conquer Hard
0316 Remove Duplicate Letters Stack,Greedy,String Medium
0317 Shortest Distance from All Buildings Breadth-first Search Hard 🔒
0318 Maximum Product of Word Lengths Bit Manipulation Medium
0319 Bulb Switcher Brainteaser,Math Medium
0320 Generalized Abbreviation Bit Manipulation,Backtracking Medium 🔒
0321 Create Maximum Number Greedy,Dynamic Programming Hard
0322 Coin Change Dynamic Programming Medium
0323 Number of Connected Components in an Undirected Graph Depth-first Search,Breadth-first Search,Union Find,Graph Medium 🔒
0324 Wiggle Sort II Sort Medium
0325 Maximum Size Subarray Sum Equals k Hash Table Medium 🔒
0326 Power of Three Math Easy
0327 Count of Range Sum Sort,Binary Indexed Tree,Segment Tree,Binary Search,Divide and Conquer Hard
0328 Odd Even Linked List Linked List Medium
0329 Longest Increasing Path in a Matrix Depth-first Search,Topological Sort,Memoization Hard
0330 Patching Array Greedy Hard
0331 Verify Preorder Serialization of a Binary Tree Stack Medium
0332 Reconstruct Itinerary Depth-first Search,Graph Medium
0333 Largest BST Subtree Tree Medium 🔒
0334 Increasing Triplet Subsequence Medium
0335 Self Crossing Math Hard
0336 Palindrome Pairs Trie,Hash Table,String Hard
0337 House Robber III Tree,Depth-first Search,Dynamic Programming Medium
0338 Counting Bits Bit Manipulation,Dynamic Programming Medium
0339 Nested List Weight Sum Depth-first Search,Breadth-first Search Medium 🔒
0340 Longest Substring with At Most K Distinct Characters Hash Table,Two Pointers,String,Sliding Window Medium 🔒
0341 Flatten Nested List Iterator Stack,Design Medium
0342 Power of Four Bit Manipulation Easy
0343 Integer Break Math,Dynamic Programming Medium
0344 Reverse String Two Pointers,String Easy
0345 Reverse Vowels of a String Two Pointers,String Easy
0346 Moving Average from Data Stream Design,Queue Easy 🔒
0347 Top K Frequent Elements Heap,Hash Table Medium
0348 Design Tic-Tac-Toe Design Medium 🔒
0349 Intersection of Two Arrays Sort,Hash Table,Two Pointers,Binary Search Easy
0350 Intersection of Two Arrays II Sort,Hash Table,Two Pointers,Binary Search Easy
0351 Android Unlock Patterns Dynamic Programming,Backtracking Medium 🔒
0352 Data Stream as Disjoint Intervals Binary Search,Ordered Map Hard
0353 Design Snake Game Design,Queue Medium 🔒
0354 Russian Doll Envelopes Binary Search,Dynamic Programming Hard
0355 Design Twitter Heap,Design,Hash Table Medium
0356 Line Reflection Hash Table,Math Medium 🔒
0357 Count Numbers with Unique Digits Math,Dynamic Programming,Backtracking Medium
0358 Rearrange String k Distance Apart Heap,Greedy,Hash Table Hard 🔒
0359 Logger Rate Limiter Design,Hash Table Easy 🔒
0360 Sort Transformed Array Sort,Math,Two Pointers Medium 🔒
0361 Bomb Enemy Dynamic Programming Medium 🔒
0362 Design Hit Counter Design Medium 🔒
0363 Max Sum of Rectangle No Larger Than K Queue,Binary Search,Dynamic Programming Hard
0364 Nested List Weight Sum II Depth-first Search Medium 🔒
0365 Water and Jug Problem Math Medium
0366 Find Leaves of Binary Tree Tree,Depth-first Search Medium 🔒
0367 Valid Perfect Square Math,Binary Search Easy
0368 Largest Divisible Subset Math,Dynamic Programming Medium
0369 Plus One Linked List Recursion,Linked List Medium 🔒
0370 Range Addition Array Medium 🔒
0371 Sum of Two Integers Bit Manipulation Medium
0372 Super Pow Math Medium
0373 Find K Pairs with Smallest Sums Heap Medium
0374 Guess Number Higher or Lower Binary Search Easy
0375 Guess Number Higher or Lower II Minimax,Dynamic Programming Medium
0376 Wiggle Subsequence Greedy,Dynamic Programming Medium
0377 Combination Sum IV Dynamic Programming Medium
0378 Kth Smallest Element in a Sorted Matrix Heap,Binary Search Medium
0379 Design Phone Directory Design,Linked List Medium 🔒
0380 Insert Delete GetRandom O(1) Design,Array,Hash Table Medium
0381 Insert Delete GetRandom O(1) - Duplicates allowed Design,Array,Hash Table Hard
0382 Linked List Random Node Reservoir Sampling Medium
0383 Ransom Note String Easy
0384 Shuffle an Array Medium
0385 Mini Parser Stack,String Medium
0386 Lexicographical Numbers Medium
0387 First Unique Character in a String Hash Table,String Easy
0388 Longest Absolute File Path Medium
0389 Find the Difference Bit Manipulation,Hash Table Easy
0390 Elimination Game Medium
0391 Perfect Rectangle Line Sweep Hard
0392 Is Subsequence Greedy,Binary Search,Dynamic Programming Easy
0393 UTF-8 Validation Bit Manipulation Medium
0394 Decode String Stack,Depth-first Search Medium
0395 Longest Substring with At Least K Repeating Characters Recursion,Divide and Conquer,Sliding Window Medium
0396 Rotate Function Math Medium
0397 Integer Replacement Bit Manipulation,Math Medium
0398 Random Pick Index Reservoir Sampling Medium
0399 Evaluate Division Union Find,Graph Medium
0400 Nth Digit Math Medium
0401 Binary Watch Bit Manipulation,Backtracking Easy
0402 Remove K Digits Stack,Greedy Medium
0403 Frog Jump Dynamic Programming Hard
0404 Sum of Left Leaves Tree Easy
0405 Convert a Number to Hexadecimal Bit Manipulation Easy
0406 Queue Reconstruction by Height Greedy Medium
0407 Trapping Rain Water II Heap,Breadth-first Search Hard
0408 Valid Word Abbreviation String Easy 🔒
0409 Longest Palindrome Hash Table Easy
0410 Split Array Largest Sum Binary Search,Dynamic Programming Hard
0411 Minimum Unique Word Abbreviation Bit Manipulation,Backtracking Hard 🔒
0412 Fizz Buzz Easy
0413 Arithmetic Slices Math,Dynamic Programming Medium
0414 Third Maximum Number Array Easy
0415 Add Strings String Easy
0416 Partition Equal Subset Sum Dynamic Programming Medium
0417 Pacific Atlantic Water Flow Depth-first Search,Breadth-first Search Medium
0418 Sentence Screen Fitting Dynamic Programming Medium 🔒
0419 Battleships in a Board Medium
0420 Strong Password Checker Hard
0421 Maximum XOR of Two Numbers in an Array Bit Manipulation,Trie Medium
0422 Valid Word Square Easy 🔒
0423 Reconstruct Original Digits from English Math Medium
0424 Longest Repeating Character Replacement Two Pointers,Sliding Window Medium
0425 Word Squares Trie,Backtracking Hard 🔒
0426 Convert Binary Search Tree to Sorted Doubly Linked List Tree,Linked List,Divide and Conquer Medium 🔒
0427 Construct Quad Tree Medium
0428 Serialize and Deserialize N-ary Tree Tree Hard 🔒
0429 N-ary Tree Level Order Traversal Tree,Breadth-first Search Medium
0430 Flatten a Multilevel Doubly Linked List Depth-first Search,Linked List Medium
0431 Encode N-ary Tree to Binary Tree Tree Hard 🔒
0432 All O`one Data Structure Design Hard
0433 Minimum Genetic Mutation Medium
0434 Number of Segments in a String String Easy
0435 Non-overlapping Intervals Greedy Medium
0436 Find Right Interval Binary Search Medium
0437 Path Sum III Tree Medium
0438 Find All Anagrams in a String Hash Table Medium
0439 Ternary Expression Parser Stack,Depth-first Search Medium 🔒
0440 K-th Smallest in Lexicographical Order Hard
0441 Arranging Coins Math,Binary Search Easy
0442 Find All Duplicates in an Array Array Medium
0443 String Compression String Medium
0444 Sequence Reconstruction Graph,Topological Sort Medium 🔒
0445 Add Two Numbers II Linked List Medium
0446 Arithmetic Slices II - Subsequence Dynamic Programming Hard
0447 Number of Boomerangs Hash Table,Math Medium
0448 Find All Numbers Disappeared in an Array Array Easy
0449 Serialize and Deserialize BST Tree Medium
0450 Delete Node in a BST Tree Medium
0451 Sort Characters By Frequency Heap,Hash Table Medium
0452 Minimum Number of Arrows to Burst Balloons Greedy,Sort Medium
0453 Minimum Moves to Equal Array Elements Math Easy
0454 4Sum II Hash Table,Binary Search Medium
0455 Assign Cookies Greedy Easy
0456 132 Pattern Stack Medium
0457 Circular Array Loop Array,Two Pointers Medium
0458 Poor Pigs Math Hard
0459 Repeated Substring Pattern String Easy
0460 LFU Cache Design Hard
0461 Hamming Distance Bit Manipulation Easy
0462 Minimum Moves to Equal Array Elements II Math Medium
0463 Island Perimeter Hash Table Easy
0464 Can I Win Minimax,Dynamic Programming Medium
0465 Optimal Account Balancing Hard 🔒
0466 Count The Repetitions Dynamic Programming Hard
0467 Unique Substrings in Wraparound String Dynamic Programming Medium
0468 Validate IP Address String Medium
0469 Convex Polygon Math Medium 🔒
0470 Implement Rand10() Using Rand7() Random,Rejection Sampling Medium
0471 Encode String with Shortest Length Dynamic Programming Hard 🔒
0472 Concatenated Words Depth-first Search,Trie,Dynamic Programming Hard
0473 Matchsticks to Square Depth-first Search Medium
0474 Ones and Zeroes Dynamic Programming Medium
0475 Heaters Binary Search Medium
0476 Number Complement Bit Manipulation Easy
0477 Total Hamming Distance Bit Manipulation Medium
0478 Generate Random Point in a Circle Math,Random,Rejection Sampling Medium
0479 Largest Palindrome Product Hard
0480 Sliding Window Median Sliding Window Hard
0481 Magical String Medium
0482 License Key Formatting Easy
0483 Smallest Good Base Math,Binary Search Hard
0484 Find Permutation Greedy Medium 🔒
0485 Max Consecutive Ones Array Easy
0486 Predict the Winner Minimax,Dynamic Programming Medium
0487 Max Consecutive Ones II Two Pointers Medium 🔒
0488 Zuma Game Depth-first Search Hard
0489 Robot Room Cleaner Depth-first Search Hard 🔒
0490 The Maze Depth-first Search,Breadth-first Search Medium 🔒
0491 Increasing Subsequences Depth-first Search Medium
0492 Construct the Rectangle Math Easy
0493 Reverse Pairs Sort,Binary Indexed Tree,Segment Tree,Binary Search,Divide and Conquer Hard
0494 Target Sum Depth-first Search,Dynamic Programming Medium
0495 Teemo Attacking Array Medium
0496 Next Greater Element I Stack Easy
0497 Random Point in Non-overlapping Rectangles Binary Search,Random Medium
0498 Diagonal Traverse Medium
0499 The Maze III Depth-first Search,Breadth-first Search Hard 🔒
0500 Keyboard Row Hash Table Easy
0501 Find Mode in Binary Search Tree Tree Easy
0502 IPO Heap,Greedy Hard
0503 Next Greater Element II Stack Medium
0504 Base 7 Easy
0505 The Maze II Depth-first Search,Breadth-first Search Medium 🔒
0506 Relative Ranks Easy
0507 Perfect Number Math Easy
0508 Most Frequent Subtree Sum Tree,Hash Table Medium
0509 Fibonacci Number Array Easy
0510 Inorder Successor in BST II Tree Medium 🔒
0511 Game Play Analysis I Easy 🔒
0512 Game Play Analysis II Easy 🔒
0513 Find Bottom Left Tree Value Tree,Depth-first Search,Breadth-first Search Medium
0514 Freedom Trail Depth-first Search,Divide and Conquer,Dynamic Programming Hard
0515 Find Largest Value in Each Tree Row Tree,Depth-first Search,Breadth-first Search Medium
0516 Longest Palindromic Subsequence Dynamic Programming Medium
0517 Super Washing Machines Math,Dynamic Programming Hard
0518 Coin Change 2 Medium
0519 Random Flip Matrix Random Medium
0520 Detect Capital String Easy
0521 Longest Uncommon Subsequence I Brainteaser,String Easy
0522 Longest Uncommon Subsequence II String Medium
0523 Continuous Subarray Sum Math,Dynamic Programming Medium
0524 Longest Word in Dictionary through Deleting Sort,Two Pointers Medium
0525 Contiguous Array Hash Table Medium
0526 Beautiful Arrangement Depth-first Search,Backtracking Medium
0527 Word Abbreviation Sort,String Hard 🔒
0528 Random Pick with Weight Binary Search,Random Medium
0529 Minesweeper Depth-first Search,Breadth-first Search Medium
0530 Minimum Absolute Difference in BST Tree Easy
0531 Lonely Pixel I Depth-first Search,Array Medium 🔒
0532 K-diff Pairs in an Array Array,Two Pointers Medium
0533 Lonely Pixel II Array Medium 🔒
0534 Game Play Analysis III Medium 🔒
0535 Encode and Decode TinyURL Hash Table,Math Medium
0536 Construct Binary Tree from String Tree,String Medium 🔒
0537 Complex Number Multiplication Math,String Medium
0538 Convert BST to Greater Tree Tree,Depth-first Search,Binary Search Tree,Recursion Medium
0539 Minimum Time Difference String Medium
0540 Single Element in a Sorted Array Binary Search Medium
0541 Reverse String II String Easy
0542 01 Matrix Depth-first Search,Breadth-first Search Medium
0543 Diameter of Binary Tree Tree Easy
0544 Output Contest Matches Recursion,String Medium 🔒
0545 Boundary of Binary Tree Tree Medium 🔒
0546 Remove Boxes Depth-first Search,Dynamic Programming Hard
0547 Number of Provinces Depth-first Search,Union Find Medium
0548 Split Array with Equal Sum Array Medium 🔒
0549 Binary Tree Longest Consecutive Sequence II Tree Medium 🔒
0550 Game Play Analysis IV Medium 🔒
0551 Student Attendance Record I String Easy
0552 Student Attendance Record II Dynamic Programming Hard
0553 Optimal Division Math,String Medium
0554 Brick Wall Hash Table Medium
0555 Split Concatenated Strings String Medium 🔒
0556 Next Greater Element III String Medium
0557 Reverse Words in a String III String Easy
0558 Logical OR of Two Binary Grids Represented as Quad-Trees Medium
0559 Maximum Depth of N-ary Tree Tree,Depth-first Search,Breadth-first Search Easy
0560 Subarray Sum Equals K Array,Hash Table Medium
0561 Array Partition I Array Easy
0562 Longest Line of Consecutive One in Matrix Array,Dynamic Programming Medium 🔒
0563 Binary Tree Tilt Tree,Depth-first Search,Recursion Easy
0564 Find the Closest Palindrome String Hard
0565 Array Nesting Array Medium
0566 Reshape the Matrix Array Easy
0567 Permutation in String Two Pointers,Sliding Window Medium
0568 Maximum Vacation Days Dynamic Programming Hard 🔒
0569 Median Employee Salary Hard 🔒
0570 Managers with at Least 5 Direct Reports Medium 🔒
0571 Find Median Given Frequency of Numbers Hard 🔒
0572 Subtree of Another Tree Tree Easy
0573 Squirrel Simulation Math Medium 🔒
0574 Winning Candidate Medium 🔒
0575 Distribute Candies Hash Table Easy
0576 Out of Boundary Paths Depth-first Search,Dynamic Programming Medium
0577 Employee Bonus Easy 🔒
0578 Get Highest Answer Rate Question Medium 🔒
0579 Find Cumulative Salary of an Employee Hard 🔒
0580 Count Student Number in Departments Medium 🔒
0581 Shortest Unsorted Continuous Subarray Array Medium
0582 Kill Process Tree,Queue Medium 🔒
0583 Delete Operation for Two Strings String Medium
0584 Find Customer Referee Easy 🔒
0585 Investments in 2016 Medium 🔒
0586 Customer Placing the Largest Number of Orders Easy 🔒
0587 Erect the Fence Geometry Hard
0588 Design In-Memory File System Design Hard 🔒
0589 N-ary Tree Preorder Traversal Tree Easy
0590 N-ary Tree Postorder Traversal Tree Easy
0591 Tag Validator Stack,String Hard
0592 Fraction Addition and Subtraction Math Medium
0593 Valid Square Math Medium
0594 Longest Harmonious Subsequence Hash Table Easy
0595 Big Countries Easy
0596 Classes More Than 5 Students Easy
0597 Friend Requests I Overall Acceptance Rate Easy 🔒
0598 Range Addition II Math Easy
0599 Minimum Index Sum of Two Lists Hash Table Easy
0600 Non-negative Integers without Consecutive Ones Dynamic Programming Hard
0601 Human Traffic of Stadium Hard
0602 Friend Requests II Who Has the Most Friends Medium 🔒
0603 Consecutive Available Seats Easy 🔒
0604 Design Compressed String Iterator Design Easy 🔒
0605 Can Place Flowers Greedy,Array Easy
0606 Construct String from Binary Tree Tree,String Easy
0607 Sales Person Easy 🔒
0608 Tree Node Medium 🔒
0609 Find Duplicate File in System Hash Table,String Medium
0610 Triangle Judgement Easy 🔒
0611 Valid Triangle Number Array Medium
0612 Shortest Distance in a Plane Medium 🔒
0613 Shortest Distance in a Line Easy 🔒
0614 Second Degree Follower Medium 🔒
0615 Average Salary Departments VS Company Hard 🔒
0616 Add Bold Tag in String String Medium 🔒
0617 Merge Two Binary Trees Tree Easy
0618 Students Report By Geography Hard 🔒
0619 Biggest Single Number Easy 🔒
0620 Not Boring Movies Easy
0621 Task Scheduler Greedy,Queue,Array Medium
0622 Design Circular Queue Design,Queue Medium
0623 Add One Row to Tree Tree Medium
0624 Maximum Distance in Arrays Array,Hash Table Medium 🔒
0625 Minimum Factorization Recursion,Math Medium 🔒
0626 Exchange Seats Medium
0627 Swap Salary Easy
0628 Maximum Product of Three Numbers Array,Math Easy
0629 K Inverse Pairs Array Dynamic Programming Hard
0630 Course Schedule III Greedy Hard
0631 Design Excel Sum Formula Design Hard 🔒
0632 Smallest Range Covering Elements from K Lists Hash Table,Two Pointers,String Hard
0633 Sum of Square Numbers Math Medium
0634 Find the Derangement of An Array Math Medium 🔒
0635 Design Log Storage System Design,String Medium 🔒
0636 Exclusive Time of Functions Stack Medium
0637 Average of Levels in Binary Tree Tree Easy
0638 Shopping Offers Depth-first Search,Dynamic Programming Medium
0639 Decode Ways II Dynamic Programming Hard
0640 Solve the Equation Math Medium
0641 Design Circular Deque Design,Queue Medium
0642 Design Search Autocomplete System Design,Trie Hard 🔒
0643 Maximum Average Subarray I Array Easy
0644 Maximum Average Subarray II Array,Binary Search Hard 🔒
0645 Set Mismatch Hash Table,Math Easy
0646 Maximum Length of Pair Chain Dynamic Programming Medium
0647 Palindromic Substrings String,Dynamic Programming Medium
0648 Replace Words Trie,Hash Table Medium
0649 Dota2 Senate Greedy Medium
0650 2 Keys Keyboard Dynamic Programming Medium
0651 4 Keys Keyboard Greedy,Math,Dynamic Programming Medium 🔒
0652 Find Duplicate Subtrees Tree Medium
0653 Two Sum IV - Input is a BST Tree Easy
0654 Maximum Binary Tree Tree Medium
0655 Print Binary Tree Tree Medium
0656 Coin Path Dynamic Programming Hard 🔒
0657 Robot Return to Origin String Easy
0658 Find K Closest Elements Binary Search Medium
0659 Split Array into Consecutive Subsequences Heap,Greedy Medium
0660 Remove 9 Math Hard 🔒
0661 Image Smoother Array Easy
0662 Maximum Width of Binary Tree Tree Medium
0663 Equal Tree Partition Tree Medium 🔒
0664 Strange Printer Depth-first Search,Dynamic Programming Hard
0665 Non-decreasing Array Array Easy
0666 Path Sum IV Tree Medium 🔒
0667 Beautiful Arrangement II Array Medium
0668 Kth Smallest Number in Multiplication Table Binary Search Hard
0669 Trim a Binary Search Tree Tree,Recursion Medium
0670 Maximum Swap Array,Math Medium
0671 Second Minimum Node In a Binary Tree Tree Easy
0672 Bulb Switcher II Math Medium
0673 Number of Longest Increasing Subsequence Dynamic Programming Medium
0674 Longest Continuous Increasing Subsequence Array Easy
0675 Cut Off Trees for Golf Event Breadth-first Search Hard
0676 Implement Magic Dictionary Trie,Hash Table Medium
0677 Map Sum Pairs Trie Medium
0678 Valid Parenthesis String String Medium
0679 24 Game Depth-first Search Hard
0680 Valid Palindrome II String Easy
0681 Next Closest Time String Medium 🔒
0682 Baseball Game Stack Easy
0683 K Empty Slots Ordered Map Hard 🔒
0684 Redundant Connection Tree,Union Find,Graph Medium
0685 Redundant Connection II Tree,Depth-first Search,Union Find,Graph Hard
0686 Repeated String Match String Medium
0687 Longest Univalue Path Tree,Recursion Medium
0688 Knight Probability in Chessboard Dynamic Programming Medium
0689 Maximum Sum of 3 Non-Overlapping Subarrays Array,Dynamic Programming Hard
0690 Employee Importance Depth-first Search,Breadth-first Search,Hash Table Easy
0691 Stickers to Spell Word Dynamic Programming,Backtracking Hard
0692 Top K Frequent Words Heap,Trie,Hash Table Medium
0693 Binary Number with Alternating Bits Bit Manipulation Easy
0694 Number of Distinct Islands Depth-first Search,Breadth-first Search,Hash Table Medium 🔒
0695 Max Area of Island Depth-first Search,Array Medium
0696 Count Binary Substrings String Easy
0697 Degree of an Array Array Easy
0698 Partition to K Equal Sum Subsets Recursion,Dynamic Programming Medium
0699 Falling Squares Segment Tree,Ordered Map Hard
0700 Search in a Binary Search Tree Tree Easy
0701 Insert into a Binary Search Tree Tree Medium
0702 Search in a Sorted Array of Unknown Size Binary Search Medium 🔒
0703 Kth Largest Element in a Stream Heap,Design Easy
0704 Binary Search Binary Search Easy
0705 Design HashSet Design,Hash Table Easy
0706 Design HashMap Design,Hash Table Easy
0707 Design Linked List Design,Linked List Medium
0708 Insert into a Sorted Circular Linked List Linked List Medium 🔒
0709 To Lower Case String Easy
0710 Random Pick with Blacklist Sort,Hash Table,Binary Search,Random Hard
0711 Number of Distinct Islands II Depth-first Search,Hash Table Hard 🔒
0712 Minimum ASCII Delete Sum for Two Strings Dynamic Programming Medium
0713 Subarray Product Less Than K Array,Two Pointers Medium
0714 Best Time to Buy and Sell Stock with Transaction Fee Greedy,Array,Dynamic Programming Medium
0715 Range Module Segment Tree,Ordered Map Hard
0716 Max Stack Design Easy 🔒
0717 1-bit and 2-bit Characters Array Easy
0718 Maximum Length of Repeated Subarray Array,Hash Table,Binary Search,Dynamic Programming Medium
0719 Find K-th Smallest Pair Distance Heap,Array,Binary Search Hard
0720 Longest Word in Dictionary Trie,Hash Table Easy
0721 Accounts Merge Depth-first Search,Union Find Medium
0722 Remove Comments String Medium
0723 Candy Crush Array,Two Pointers Medium 🔒
0724 Find Pivot Index Array Easy
0725 Split Linked List in Parts Linked List Medium
0726 Number of Atoms Stack,Recursion,Hash Table Hard
0727 Minimum Window Subsequence Dynamic Programming,Sliding Window Hard 🔒
0728 Self Dividing Numbers Math Easy
0729 My Calendar I Array Medium
0730 Count Different Palindromic Subsequences String,Dynamic Programming Hard
0731 My Calendar II Ordered Map Medium
0732 My Calendar III Segment Tree,Ordered Map Hard
0733 Flood Fill Depth-first Search Easy
0734 Sentence Similarity Hash Table Easy 🔒
0735 Asteroid Collision Stack Medium
0736 Parse Lisp Expression String Hard
0737 Sentence Similarity II Depth-first Search,Union Find Medium 🔒
0738 Monotone Increasing Digits Greedy Medium
0739 Daily Temperatures Stack,Hash Table Medium
0740 Delete and Earn Dynamic Programming Medium
0741 Cherry Pickup Dynamic Programming Hard
0742 Closest Leaf in a Binary Tree Tree Medium 🔒
0743 Network Delay Time Heap,Depth-first Search,Breadth-first Search,Graph Medium
0744 Find Smallest Letter Greater Than Target Binary Search Easy
0745 Prefix and Suffix Search Trie Hard
0746 Min Cost Climbing Stairs Array,Dynamic Programming Easy
0747 Largest Number At Least Twice of Others Array Easy
0748 Shortest Completing Word Hash Table Easy
0749 Contain Virus Depth-first Search Hard
0750 Number Of Corner Rectangles Dynamic Programming Medium 🔒
0751 IP to CIDR Bit Manipulation Easy 🔒
0752 Open the Lock Breadth-first Search Medium
0753 Cracking the Safe Depth-first Search,Math Hard
0754 Reach a Number Math Medium
0755 Pour Water Array Medium 🔒
0756 Pyramid Transition Matrix Bit Manipulation,Depth-first Search Medium
0757 Set Intersection Size At Least Two Greedy Hard
0758 Bold Words in String String Easy 🔒
0759 Employee Free Time Heap,Greedy Hard 🔒
0760 Find Anagram Mappings Hash Table Easy 🔒
0761 Special Binary String Recursion,String Hard
0762 Prime Number of Set Bits in Binary Representation Bit Manipulation Easy
0763 Partition Labels Greedy,Two Pointers Medium
0764 Largest Plus Sign Dynamic Programming Medium
0765 Couples Holding Hands Greedy,Union Find,Graph Hard
0766 Toeplitz Matrix Array Easy
0767 Reorganize String Heap,Greedy,Sort,String Medium
0768 Max Chunks To Make Sorted II Array Hard
0769 Max Chunks To Make Sorted Array Medium
0770 Basic Calculator IV Stack,Hash Table,String Hard
0771 Jewels and Stones Hash Table Easy
0772 Basic Calculator III Stack,String Hard 🔒
0773 Sliding Puzzle Breadth-first Search Hard
0774 Minimize Max Distance to Gas Station Binary Search Hard 🔒
0775 Global and Local Inversions Array,Math Medium
0776 Split BST Tree,Recursion Medium 🔒
0777 Swap Adjacent in LR String Brainteaser Medium
0778 Swim in Rising Water Heap,Depth-first Search,Union Find,Binary Search Hard
0779 K-th Symbol in Grammar Recursion Medium
0780 Reaching Points Math Hard
0781 Rabbits in Forest Hash Table,Math Medium
0782 Transform to Chessboard Array,Math Hard
0783 Minimum Distance Between BST Nodes Tree,Depth-first Search,Recursion Easy
0784 Letter Case Permutation Bit Manipulation,Backtracking Medium
0785 Is Graph Bipartite Depth-first Search,Breadth-first Search,Graph Medium
0786 K-th Smallest Prime Fraction Heap,Binary Search Hard
0787 Cheapest Flights Within K Stops Heap,Breadth-first Search,Dynamic Programming Medium
0788 Rotated Digits String Easy
0789 Escape The Ghosts Math Medium
0790 Domino and Tromino Tiling Dynamic Programming Medium
0791 Custom Sort String String Medium
0792 Number of Matching Subsequences Array Medium
0793 Preimage Size of Factorial Zeroes Function Binary Search Hard
0794 Valid Tic-Tac-Toe State Recursion,Math Medium
0795 Number of Subarrays with Bounded Maximum Array Medium
0796 Rotate String Easy
0797 All Paths From Source to Target Depth-first Search,Graph,Backtracking Medium
0798 Smallest Rotation with Highest Score Hard
0799 Champagne Tower Dynamic Programming Medium
0800 Similar RGB Color Math,String Easy 🔒
0801 Minimum Swaps To Make Sequences Increasing Dynamic Programming Medium
0802 Find Eventual Safe States Depth-first Search,Graph Medium
0803 Bricks Falling When Hit Union Find Hard
0804 Unique Morse Code Words String Easy
0805 Split Array With Same Average Math Hard
0806 Number of Lines To Write String Easy
0807 Max Increase to Keep City Skyline Medium
0808 Soup Servings Dynamic Programming Medium
0809 Expressive Words String Medium
0810 Chalkboard XOR Game Math Hard
0811 Subdomain Visit Count Hash Table Easy
0812 Largest Triangle Area Math Easy
0813 Largest Sum of Averages Dynamic Programming Medium
0814 Binary Tree Pruning Tree Medium
0815 Bus Routes Breadth-first Search Hard
0816 Ambiguous Coordinates String Medium
0817 Linked List Components Linked List Medium
0818 Race Car Heap,Dynamic Programming Hard
0819 Most Common Word String Easy
0820 Short Encoding of Words Medium
0821 Shortest Distance to a Character Easy
0822 Card Flipping Game Medium
0823 Binary Trees With Factors Medium
0824 Goat Latin String Easy
0825 Friends Of Appropriate Ages Array Medium
0826 Most Profit Assigning Work Two Pointers Medium
0827 Making A Large Island Depth-first Search,Breadth-first Search Hard
0828 Count Unique Characters of All Substrings of a Given String Two Pointers Hard
0829 Consecutive Numbers Sum Math Hard
0830 Positions of Large Groups Array Easy
0831 Masking Personal Information String Medium
0832 Flipping an Image Array Easy
0833 Find And Replace in String String Medium
0834 Sum of Distances in Tree Tree,Depth-first Search Hard
0835 Image Overlap Array Medium
0836 Rectangle Overlap Math Easy
0837 New 21 Game Dynamic Programming Medium
0838 Push Dominoes Two Pointers,Dynamic Programming Medium
0839 Similar String Groups Depth-first Search,Union Find,Graph Hard
0840 Magic Squares In Grid Array Medium
0841 Keys and Rooms Depth-first Search,Graph Medium
0842 Split Array into Fibonacci Sequence Greedy,String,Backtracking Medium
0843 Guess the Word Minimax Hard
0844 Backspace String Compare Stack,Two Pointers Easy
0845 Longest Mountain in Array Two Pointers Medium
0846 Hand of Straights Ordered Map Medium
0847 Shortest Path Visiting All Nodes Breadth-first Search,Dynamic Programming Hard
0848 Shifting Letters String Medium
0849 Maximize Distance to Closest Person Array Medium
0850 Rectangle Area II Segment Tree,Line Sweep Hard
0851 Loud and Rich Depth-first Search Medium
0852 Peak Index in a Mountain Array Binary Search Easy
0853 Car Fleet Sort Medium
0854 K-Similar Strings Breadth-first Search,Graph Hard
0855 Exam Room Ordered Map Medium
0856 Score of Parentheses Stack,String Medium
0857 Minimum Cost to Hire K Workers Heap Hard
0858 Mirror Reflection Math Medium
0859 Buddy Strings String Easy
0860 Lemonade Change Greedy Easy
0861 Score After Flipping Matrix Greedy Medium
0862 Shortest Subarray with Sum at Least K Queue,Binary Search Hard
0863 All Nodes Distance K in Binary Tree Tree,Depth-first Search,Breadth-first Search Medium
0864 Shortest Path to Get All Keys Heap,Breadth-first Search Hard
0865 Smallest Subtree with all the Deepest Nodes Tree,Depth-first Search,Breadth-first Search,Recursion Medium
0866 Prime Palindrome Math Medium
0867 Transpose Matrix Array Easy
0868 Binary Gap Math Easy
0869 Reordered Power of 2 Math Medium
0870 Advantage Shuffle Greedy,Array Medium
0871 Minimum Number of Refueling Stops Heap,Dynamic Programming Hard
0872 Leaf-Similar Trees Tree,Depth-first Search Easy
0873 Length of Longest Fibonacci Subsequence Array,Dynamic Programming Medium
0874 Walking Robot Simulation Greedy Easy
0875 Koko Eating Bananas Binary Search Medium
0876 Middle of the Linked List Linked List Easy
0877 Stone Game Minimax,Math,Dynamic Programming Medium
0878 Nth Magical Number Math,Binary Search Hard
0879 Profitable Schemes Dynamic Programming Hard
0880 Decoded String at Index Stack Medium
0881 Boats to Save People Greedy,Two Pointers Medium
0882 Reachable Nodes In Subdivided Graph Heap,Breadth-first Search Hard
0883 Projection Area of 3D Shapes Math Easy
0884 Uncommon Words from Two Sentences Hash Table Easy
0885 Spiral Matrix III Math Medium
0886 Possible Bipartition Depth-first Search,Graph Medium
0887 Super Egg Drop Math,Binary Search,Dynamic Programming Hard
0888 Fair Candy Swap Array Easy
0889 Construct Binary Tree from Preorder and Postorder Traversal Tree Medium
0890 Find and Replace Pattern String Medium
0891 Sum of Subsequence Widths Array,Math Hard
0892 Surface Area of 3D Shapes Geometry,Math Easy
0893 Groups of Special-Equivalent Strings String Easy
0894 All Possible Full Binary Trees Tree,Recursion Medium
0895 Maximum Frequency Stack Stack,Hash Table Hard
0896 Monotonic Array Array Easy
0897 Increasing Order Search Tree Tree,Depth-first Search,Recursion Easy
0898 Bitwise ORs of Subarrays Bit Manipulation,Dynamic Programming Medium
0899 Orderly Queue Math,String Hard
0900 RLE Iterator Array Medium
0901 Online Stock Span Stack Medium
0902 Numbers At Most N Given Digit Set Math,Dynamic Programming Hard
0903 Valid Permutations for DI Sequence Divide and Conquer,Dynamic Programming Hard
0904 Fruit Into Baskets Two Pointers Medium
0905 Sort Array By Parity Array Easy
0906 Super Palindromes Math Hard
0907 Sum of Subarray Minimums Stack,Array Medium
0908 Smallest Range I Math Easy
0909 Snakes and Ladders Breadth-first Search Medium
0910 Smallest Range II Greedy,Math Medium
0911 Online Election Binary Search Medium
0912 Sort an Array Medium
0913 Cat and Mouse Breadth-first Search,Minimax Hard
0914 X of a Kind in a Deck of Cards Array,Math Easy
0915 Partition Array into Disjoint Intervals Array Medium
0916 Word Subsets String Medium
0917 Reverse Only Letters String Easy
0918 Maximum Sum Circular Subarray Array Medium
0919 Complete Binary Tree Inserter Tree Medium
0920 Number of Music Playlists Dynamic Programming Hard
0921 Minimum Add to Make Parentheses Valid Stack,Greedy Medium
0922 Sort Array By Parity II Sort,Array Easy
0923 3Sum With Multiplicity Two Pointers Medium
0924 Minimize Malware Spread Depth-first Search,Union Find Hard
0925 Long Pressed Name Two Pointers,String Easy
0926 Flip String to Monotone Increasing Array Medium
0927 Three Equal Parts Greedy,Math,Binary Search Hard
0928 Minimize Malware Spread II Depth-first Search,Union Find,Graph Hard
0929 Unique Email Addresses String Easy
0930 Binary Subarrays With Sum Hash Table,Two Pointers Medium
0931 Minimum Falling Path Sum Dynamic Programming Medium
0932 Beautiful Array Divide and Conquer Medium
0933 Number of Recent Calls Queue Easy
0934 Shortest Bridge Depth-first Search,Breadth-first Search Medium
0935 Knight Dialer Dynamic Programming Medium
0936 Stamping The Sequence Greedy,String Hard
0937 Reorder Data in Log Files String Easy
0938 Range Sum of BST Tree,Depth-first Search,Recursion Easy
0939 Minimum Area Rectangle Hash Table Medium
0940 Distinct Subsequences II Dynamic Programming Hard
0941 Valid Mountain Array Array Easy
0942 DI String Match Math Easy
0943 Find the Shortest Superstring Dynamic Programming Hard
0944 Delete Columns to Make Sorted Greedy Easy
0945 Minimum Increment to Make Array Unique Array Medium
0946 Validate Stack Sequences Stack Medium
0947 Most Stones Removed with Same Row or Column Depth-first Search,Union Find Medium
0948 Bag of Tokens Greedy,Sort,Two Pointers Medium
0949 Largest Time for Given Digits Math Medium
0950 Reveal Cards In Increasing Order Array Medium
0951 Flip Equivalent Binary Trees Tree Medium
0952 Largest Component Size by Common Factor Union Find,Math Hard
0953 Verifying an Alien Dictionary Hash Table Easy
0954 Array of Doubled Pairs Array,Hash Table Medium
0955 Delete Columns to Make Sorted II Greedy Medium
0956 Tallest Billboard Dynamic Programming Hard
0957 Prison Cells After N Days Hash Table Medium
0958 Check Completeness of a Binary Tree Tree Medium
0959 Regions Cut By Slashes Depth-first Search,Union Find,Graph Medium
0960 Delete Columns to Make Sorted III Dynamic Programming Hard
0961 N-Repeated Element in Size 2N Array Hash Table Easy
0962 Maximum Width Ramp Array Medium
0963 Minimum Area Rectangle II Geometry,Math Medium
0964 Least Operators to Express Number Math,Dynamic Programming Hard
0965 Univalued Binary Tree Tree Easy
0966 Vowel Spellchecker Hash Table,String Medium
0967 Numbers With Same Consecutive Differences Depth-first Search,Breadth-first Search,Recursion,Backtracking Medium
0968 Binary Tree Cameras Tree,Depth-first Search,Dynamic Programming Hard
0969 Pancake Sorting Sort,Array Medium
0970 Powerful Integers Hash Table,Math Medium
0971 Flip Binary Tree To Match Preorder Traversal Tree,Depth-first Search Medium
0972 Equal Rational Numbers Math Hard
0973 K Closest Points to Origin Heap,Sort,Divide and Conquer Medium
0974 Subarray Sums Divisible by K Array,Hash Table Medium
0975 Odd Even Jump Stack,Dynamic Programming,Ordered Map Hard
0976 Largest Perimeter Triangle Sort,Math Easy
0977 Squares of a Sorted Array Array,Two Pointers Easy
0978 Longest Turbulent Subarray Array,Dynamic Programming,Sliding Window Medium
0979 Distribute Coins in Binary Tree Tree,Depth-first Search Medium
0980 Unique Paths III Depth-first Search,Backtracking Hard
0981 Time Based Key-Value Store Hash Table,Binary Search Medium
0982 Triples with Bitwise AND Equal To Zero Dynamic Programming Hard
0983 Minimum Cost For Tickets Dynamic Programming Medium
0984 String Without AAA or BBB Greedy Medium
0985 Sum of Even Numbers After Queries Array Easy
0986 Interval List Intersections Two Pointers Medium
0987 Vertical Order Traversal of a Binary Tree Tree,Depth-first Search,Breadth-first Search,Hash Table Hard
0988 Smallest String Starting From Leaf Tree,Depth-first Search Medium
0989 Add to Array-Form of Integer Array Easy
0990 Satisfiability of Equality Equations Union Find,Graph Medium
0991 Broken Calculator Greedy,Math Medium
0992 Subarrays with K Different Integers Hash Table,Two Pointers,Sliding Window Hard
0993 Cousins in Binary Tree Tree,Breadth-first Search Easy
0994 Rotting Oranges Breadth-first Search Medium
0995 Minimum Number of K Consecutive Bit Flips Greedy,Sliding Window Hard
0996 Number of Squareful Arrays Graph,Math,Backtracking Hard
0997 Find the Town Judge Graph Easy
0998 Maximum Binary Tree II Tree Medium
0999 Available Captures for Rook Array Easy
1000 Minimum Cost to Merge Stones Dynamic Programming Hard
1001 Grid Illumination Hash Table Hard
1002 Find Common Characters Array,Hash Table Easy
1003 Check If Word Is Valid After Substitutions Stack,String Medium
1004 Max Consecutive Ones III Two Pointers,Sliding Window Medium
1005 Maximize Sum Of Array After K Negations Greedy Easy
1006 Clumsy Factorial Math Medium
1007 Minimum Domino Rotations For Equal Row Greedy,Array Medium
1008 Construct Binary Search Tree from Preorder Traversal Tree Medium
1009 Complement of Base 10 Integer Math Easy
1010 Pairs of Songs With Total Durations Divisible by 60 Array Medium
1011 Capacity To Ship Packages Within D Days Array,Binary Search Medium
1012 Numbers With Repeated Digits Math,Dynamic Programming Hard
1013 Partition Array Into Three Parts With Equal Sum Array Easy
1014 Best Sightseeing Pair Array Medium
1015 Smallest Integer Divisible by K Math Medium
1016 Binary String With Substrings Representing 1 To N String Medium
1017 Convert to Base -2 Math Medium
1018 Binary Prefix Divisible By 5 Array Easy
1019 Next Greater Node In Linked List Stack,Linked List Medium
1020 Number of Enclaves Depth-first Search Medium
1021 Remove Outermost Parentheses Stack Easy
1022 Sum of Root To Leaf Binary Numbers Tree Easy
1023 Camelcase Matching Trie,String Medium
1024 Video Stitching Dynamic Programming Medium
1025 Divisor Game Math,Dynamic Programming Easy
1026 Maximum Difference Between Node and Ancestor Tree,Depth-first Search Medium
1027 Longest Arithmetic Subsequence Dynamic Programming Medium
1028 Recover a Tree From Preorder Traversal Tree,Depth-first Search Hard
1029 Two City Scheduling Greedy Medium
1030 Matrix Cells in Distance Order Sort Easy
1031 Maximum Sum of Two Non-Overlapping Subarrays Array Medium
1032 Stream of Characters Trie Hard
1033 Moving Stones Until Consecutive Brainteaser Easy
1034 Coloring A Border Depth-first Search Medium
1035 Uncrossed Lines Array Medium
1036 Escape a Large Maze Breadth-first Search Hard
1037 Valid Boomerang Math Easy
1038 Binary Search Tree to Greater Sum Tree Tree,Depth-first Search,Binary Search Tree,Recursion Medium
1039 Minimum Score Triangulation of Polygon Dynamic Programming Medium
1040 Moving Stones Until Consecutive II Array,Sliding Window Medium
1041 Robot Bounded In Circle Math Medium
1042 Flower Planting With No Adjacent Graph Medium
1043 Partition Array for Maximum Sum Dynamic Programming Medium
1044 Longest Duplicate Substring Hash Table,Binary Search Hard
1045 Customers Who Bought All Products Medium 🔒
1046 Last Stone Weight Heap,Greedy Easy
1047 Remove All Adjacent Duplicates In String Stack Easy
1048 Longest String Chain Hash Table,Dynamic Programming Medium
1049 Last Stone Weight II Dynamic Programming Medium
1050 Actors and Directors Who Cooperated At Least Three Times Easy 🔒
1051 Height Checker Array Easy
1052 Grumpy Bookstore Owner Array,Sliding Window Medium
1053 Previous Permutation With One Swap Greedy,Array Medium
1054 Distant Barcodes Heap,Sort Medium
1055 Shortest Way to Form String Greedy,Dynamic Programming Medium 🔒
1056 Confusing Number Math Easy 🔒
1057 Campus Bikes Greedy,Sort Medium 🔒
1058 Minimize Rounding Error to Meet Target Greedy,Math,Dynamic Programming Medium 🔒
1059 All Paths from Source Lead to Destination Depth-first Search,Graph Medium 🔒
1060 Missing Element in Sorted Array Binary Search Medium 🔒
1061 Lexicographically Smallest Equivalent String Depth-first Search,Union Find Medium 🔒
1062 Longest Repeating Substring String Medium 🔒
1063 Number of Valid Subarrays Stack Hard 🔒
1064 Fixed Point Array,Binary Search Easy 🔒
1065 Index Pairs of a String Trie,String Easy 🔒
1066 Campus Bikes II Dynamic Programming,Backtracking Medium 🔒
1067 Digit Count in Range Math,Dynamic Programming Hard 🔒
1068 Product Sales Analysis I Easy 🔒
1069 Product Sales Analysis II Easy 🔒
1070 Product Sales Analysis III Medium 🔒
1071 Greatest Common Divisor of Strings String Easy
1072 Flip Columns For Maximum Number of Equal Rows Hash Table Medium
1073 Adding Two Negabinary Numbers Math Medium
1074 Number of Submatrices That Sum to Target Array,Dynamic Programming,Sliding Window Hard
1075 Project Employees I Easy 🔒
1076 Project Employees II Easy 🔒
1077 Project Employees III Medium 🔒
1078 Occurrences After Bigram Hash Table Easy
1079 Letter Tile Possibilities Backtracking Medium
1080 Insufficient Nodes in Root to Leaf Paths Depth-first Search Medium
1081 Smallest Subsequence of Distinct Characters Stack,Greedy,String Medium
1082 Sales Analysis I Easy 🔒
1083 Sales Analysis II Easy 🔒
1084 Sales Analysis III Easy 🔒
1085 Sum of Digits in the Minimum Number Array Easy 🔒
1086 High Five Sort,Array,Hash Table Easy 🔒
1087 Brace Expansion Backtracking Medium 🔒
1088 Confusing Number II Math,Backtracking Hard 🔒
1089 Duplicate Zeros Array Easy
1090 Largest Values From Labels Greedy,Hash Table Medium
1091 Shortest Path in Binary Matrix Breadth-first Search Medium
1092 Shortest Common Supersequence Dynamic Programming Hard
1093 Statistics from a Large Sample Math,Two Pointers Medium
1094 Car Pooling Greedy Medium
1095 Find in Mountain Array Binary Search Hard
1096 Brace Expansion II String Hard
1097 Game Play Analysis V Hard 🔒
1098 Unpopular Books Medium 🔒
1099 Two Sum Less Than K Sort,Array,Two Pointers Easy 🔒
1100 Find K-Length Substrings With No Repeated Characters String,Sliding Window Medium 🔒
1101 The Earliest Moment When Everyone Become Friends Union Find Medium 🔒
1102 Path With Maximum Minimum Value Depth-first Search,Union Find,Graph Medium 🔒
1103 Distribute Candies to People Math Easy
1104 Path In Zigzag Labelled Binary Tree Tree,Math Medium
1105 Filling Bookcase Shelves Dynamic Programming Medium
1106 Parsing A Boolean Expression String Hard
1107 New Users Daily Count Medium 🔒
1108 Defanging an IP Address String Easy
1109 Corporate Flight Bookings Array,Math Medium
1110 Delete Nodes And Return Forest Tree,Depth-first Search Medium
1111 Maximum Nesting Depth of Two Valid Parentheses Strings Greedy,Binary Search Medium
1112 Highest Grade For Each Student Medium 🔒
1113 Reported Posts Easy 🔒
1114 Print in Order Easy
1115 Print FooBar Alternately Medium
1116 Print Zero Even Odd Medium
1117 Building H2O Medium
1118 Number of Days in a Month Easy 🔒
1119 Remove Vowels from a String String Easy 🔒
1120 Maximum Average Subtree Tree Medium 🔒
1121 Divide Array Into Increasing Sequences Math Hard 🔒
1122 Relative Sort Array Sort,Array Easy
1123 Lowest Common Ancestor of Deepest Leaves Tree,Depth-first Search Medium
1124 Longest Well-Performing Interval Stack Medium
1125 Smallest Sufficient Team Bit Manipulation,Dynamic Programming Hard
1126 Active Businesses Medium 🔒
1127 User Purchase Platform Hard 🔒
1128 Number of Equivalent Domino Pairs Array Easy
1129 Shortest Path with Alternating Colors Breadth-first Search,Graph Medium
1130 Minimum Cost Tree From Leaf Values Stack,Tree,Dynamic Programming Medium
1131 Maximum of Absolute Value Expression Bit Manipulation,Math Medium
1132 Reported Posts II Medium 🔒
1133 Largest Unique Number Array,Hash Table Easy 🔒
1134 Armstrong Number Math Easy 🔒
1135 Connecting Cities With Minimum Cost Union Find,Graph Medium 🔒
1136 Parallel Courses Depth-first Search,Graph,Dynamic Programming Medium 🔒
1137 N-th Tribonacci Number Recursion Easy
1138 Alphabet Board Path Hash Table,String Medium
1139 Largest 1-Bordered Square Dynamic Programming Medium
1140 Stone Game II Dynamic Programming Medium
1141 User Activity for the Past 30 Days I Easy 🔒
1142 User Activity for the Past 30 Days II Easy 🔒
1143 Longest Common Subsequence Dynamic Programming Medium
1144 Decrease Elements To Make Array Zigzag Array Medium
1145 Binary Tree Coloring Game Tree,Depth-first Search Medium
1146 Snapshot Array Array Medium
1147 Longest Chunked Palindrome Decomposition Dynamic Programming Hard
1148 Article Views I Easy 🔒
1149 Article Views II Medium 🔒
1150 Check If a Number Is Majority Element in a Sorted Array Array,Binary Search Easy 🔒
1151 Minimum Swaps to Group All 1's Together Array,Sliding Window Medium 🔒
1152 Analyze User Website Visit Pattern Sort,Array,Hash Table Medium 🔒
1153 String Transforms Into Another String Graph Hard 🔒
1154 Day of the Year Math Easy
1155 Number of Dice Rolls With Target Sum Dynamic Programming Medium
1156 Swap For Longest Repeated Character Substring String Medium
1157 Online Majority Element In Subarray Segment Tree,Array,Binary Search Hard
1158 Market Analysis I Medium 🔒
1159 Market Analysis II Hard 🔒
1160 Find Words That Can Be Formed by Characters Array,Hash Table Easy
1161 Maximum Level Sum of a Binary Tree Tree,Breadth-first Search Medium
1162 As Far from Land as Possible Breadth-first Search,Graph Medium
1163 Last Substring in Lexicographical Order String Hard
1164 Product Price at a Given Date Medium 🔒
1165 Single-Row Keyboard String Easy 🔒
1166 Design File System Design,Hash Table Medium 🔒
1167 Minimum Cost to Connect Sticks Greedy Medium 🔒
1168 Optimize Water Distribution in a Village Union Find,Graph Hard 🔒
1169 Invalid Transactions Array,String Medium
1170 Compare Strings by Frequency of the Smallest Character Array,String,Binary Search Medium
1171 Remove Zero Sum Consecutive Nodes from Linked List Linked List Medium
1172 Dinner Plate Stacks Design Hard
1173 Immediate Food Delivery I Easy 🔒
1174 Immediate Food Delivery II Medium 🔒
1175 Prime Arrangements Math Easy
1176 Diet Plan Performance Array,Sliding Window Easy 🔒
1177 Can Make Palindrome from Substring Array,String Medium
1178 Number of Valid Words for Each Puzzle Bit Manipulation,Hash Table Hard
1179 Reformat Department Table Easy
1180 Count Substrings with Only One Distinct Letter Math,String Easy 🔒
1181 Before and After Puzzle String Medium 🔒
1182 Shortest Distance to Target Color Binary Search Medium 🔒
1183 Maximum Number of Ones Sort,Math Hard 🔒
1184 Distance Between Bus Stops Array Easy
1185 Day of the Week Array Easy
1186 Maximum Subarray Sum with One Deletion Dynamic Programming Medium
1187 Make Array Strictly Increasing Dynamic Programming Hard
1188 Design Bounded Blocking Queue Medium 🔒
1189 Maximum Number of Balloons Hash Table,String Easy
1190 Reverse Substrings Between Each Pair of Parentheses Stack Medium
1191 K-Concatenation Maximum Sum Dynamic Programming Medium
1192 Critical Connections in a Network Depth-first Search Hard
1193 Monthly Transactions I Medium 🔒
1194 Tournament Winners Hard 🔒
1195 Fizz Buzz Multithreaded Medium
1196 How Many Apples Can You Put into the Basket Greedy Easy 🔒
1197 Minimum Knight Moves Breadth-first Search Medium 🔒
1198 Find Smallest Common Element in All Rows Hash Table,Binary Search Medium 🔒
1199 Minimum Time to Build Blocks Math,Dynamic Programming Hard 🔒
1200 Minimum Absolute Difference Array Easy
1201 Ugly Number III Math,Binary Search Medium
1202 Smallest String With Swaps Union Find,Array Medium
1203 Sort Items by Groups Respecting Dependencies Depth-first Search,Graph,Topological Sort Hard
1204 Last Person to Fit in the Elevator Medium 🔒
1205 Monthly Transactions II Medium 🔒
1206 Design Skiplist Design Hard
1207 Unique Number of Occurrences Hash Table Easy
1208 Get Equal Substrings Within Budget Array,Sliding Window Medium
1209 Remove All Adjacent Duplicates in String II Stack Medium
1210 Minimum Moves to Reach Target with Rotations Breadth-first Search Hard
1211 Queries Quality and Percentage Easy 🔒
1212 Team Scores in Football Tournament Medium 🔒
1213 Intersection of Three Sorted Arrays Hash Table,Two Pointers Easy 🔒
1214 Two Sum BSTs Binary Search Tree Medium 🔒
1215 Stepping Numbers Backtracking Medium 🔒
1216 Valid Palindrome III String,Dynamic Programming Hard 🔒
1217 Minimum Cost to Move Chips to The Same Position Greedy,Array,Math Easy
1218 Longest Arithmetic Subsequence of Given Difference Hash Table,Math,Dynamic Programming Medium
1219 Path with Maximum Gold Backtracking Medium
1220 Count Vowels Permutation Dynamic Programming Hard
1221 Split a String in Balanced Strings Greedy,String Easy
1222 Queens That Can Attack the King Array Medium
1223 Dice Roll Simulation Dynamic Programming Medium
1224 Maximum Equal Frequency Hash Table Hard
1225 Report Contiguous Dates Hard 🔒
1226 The Dining Philosophers Medium
1227 Airplane Seat Assignment Probability Brainteaser,Math,Dynamic Programming Medium
1228 Missing Number In Arithmetic Progression Math Easy 🔒
1229 Meeting Scheduler Sort,Two Pointers,Line Sweep Medium 🔒
1230 Toss Strange Coins Math,Dynamic Programming Medium 🔒
1231 Divide Chocolate Greedy,Binary Search Hard 🔒
1232 Check If It Is a Straight Line Geometry,Array,Math Easy
1233 Remove Sub-Folders from the Filesystem Array,String Medium
1234 Replace the Substring for Balanced String Two Pointers,String Medium
1235 Maximum Profit in Job Scheduling Sort,Binary Search,Dynamic Programming Hard
1236 Web Crawler Depth-first Search,Breadth-first Search Medium 🔒
1237 Find Positive Integer Solution for a Given Equation Math,Binary Search Medium
1238 Circular Permutation in Binary Representation Math Medium
1239 Maximum Length of a Concatenated String with Unique Characters Bit Manipulation,Backtracking Medium
1240 Tiling a Rectangle with the Fewest Squares Dynamic Programming,Backtracking Hard
1241 Number of Comments per Post Easy 🔒
1242 Web Crawler Multithreaded Depth-first Search,Breadth-first Search Medium 🔒
1243 Array Transformation Array Easy 🔒
1244 Design A Leaderboard Sort,Design,Hash Table Medium 🔒
1245 Tree Diameter Tree,Depth-first Search,Breadth-first Search Medium 🔒
1246 Palindrome Removal Dynamic Programming Hard 🔒
1247 Minimum Swaps to Make Strings Equal Greedy,String Medium
1248 Count Number of Nice Subarrays Two Pointers Medium
1249 Minimum Remove to Make Valid Parentheses Stack,String Medium
1250 Check If It Is a Good Array Math Hard
1251 Average Selling Price Easy 🔒
1252 Cells with Odd Values in a Matrix Array Easy
1253 Reconstruct a 2-Row Binary Matrix Greedy,Math Medium
1254 Number of Closed Islands Depth-first Search Medium
1255 Maximum Score Words Formed by Letters Bit Manipulation Hard
1256 Encode Number Bit Manipulation,Math Medium 🔒
1257 Smallest Common Region Tree Medium 🔒
1258 Synonymous Sentences Backtracking Medium 🔒
1259 Handshakes That Don't Cross Math,Dynamic Programming Hard 🔒
1260 Shift 2D Grid Array Easy
1261 Find Elements in a Contaminated Binary Tree Tree,Hash Table Medium
1262 Greatest Sum Divisible by Three Dynamic Programming Medium
1263 Minimum Moves to Move a Box to Their Target Location Breadth-first Search Hard
1264 Page Recommendations Medium 🔒
1265 Print Immutable Linked List in Reverse Medium 🔒
1266 Minimum Time Visiting All Points Geometry,Array Easy
1267 Count Servers that Communicate Graph,Array Medium
1268 Search Suggestions System String Medium
1269 Number of Ways to Stay in the Same Place After Some Steps Dynamic Programming Hard
1270 All People Report to the Given Manager Medium 🔒
1271 Hexspeak Math,String Easy 🔒
1272 Remove Interval Math,Line Sweep Medium 🔒
1273 Delete Tree Nodes Depth-first Search,Dynamic Programming Medium 🔒
1274 Number of Ships in a Rectangle Divide and Conquer Hard 🔒
1275 Find Winner on a Tic Tac Toe Game Array Easy
1276 Number of Burgers with No Waste of Ingredients Greedy,Math Medium
1277 Count Square Submatrices with All Ones Array,Dynamic Programming Medium
1278 Palindrome Partitioning III Dynamic Programming Hard
1279 Traffic Light Controlled Intersection Easy 🔒
1280 Students and Examinations Easy 🔒
1281 Subtract the Product and Sum of Digits of an Integer Math Easy
1282 Group the People Given the Group Size They Belong To Greedy Medium
1283 Find the Smallest Divisor Given a Threshold Binary Search Medium
1284 Minimum Number of Flips to Convert Binary Matrix to Zero Matrix Breadth-first Search Hard
1285 Find the Start and End Number of Continuous Ranges Medium 🔒
1286 Iterator for Combination Design,Backtracking Medium
1287 Element Appearing More Than 25% In Sorted Array Array Easy
1288 Remove Covered Intervals Greedy,Sort,Line Sweep Medium
1289 Minimum Falling Path Sum II Dynamic Programming Hard
1290 Convert Binary Number in a Linked List to Integer Bit Manipulation,Linked List Easy
1291 Sequential Digits Backtracking Medium
1292 Maximum Side Length of a Square with Sum Less than or Equal to Threshold Array,Binary Search Medium
1293 Shortest Path in a Grid with Obstacles Elimination Breadth-first Search Hard
1294 Weather Type in Each Country Easy 🔒
1295 Find Numbers with Even Number of Digits Array Easy
1296 Divide Array in Sets of K Consecutive Numbers Greedy,Array Medium
1297 Maximum Number of Occurrences of a Substring Bit Manipulation,String Medium
1298 Maximum Candies You Can Get from Boxes Breadth-first Search Hard
1299 Replace Elements with Greatest Element on Right Side Array Easy
1300 Sum of Mutated Array Closest to Target Array,Binary Search Medium
1301 Number of Paths with Max Score Dynamic Programming Hard
1302 Deepest Leaves Sum Tree,Depth-first Search Medium
1303 Find the Team Size Easy 🔒
1304 Find N Unique Integers Sum up to Zero Array Easy
1305 All Elements in Two Binary Search Trees Sort,Tree Medium
1306 Jump Game III Depth-first Search,Breadth-first Search,Recursion Medium
1307 Verbal Arithmetic Puzzle Math,Backtracking Hard
1308 Running Total for Different Genders Medium 🔒
1309 Decrypt String from Alphabet to Integer Mapping String Easy
1310 XOR Queries of a Subarray Bit Manipulation Medium
1311 Get Watched Videos by Your Friends Breadth-first Search,Hash Table,String Medium
1312 Minimum Insertion Steps to Make a String Palindrome Dynamic Programming Hard
1313 Decompress Run-Length Encoded List Array Easy
1314 Matrix Block Sum Dynamic Programming Medium
1315 Sum of Nodes with Even-Valued Grandparent Tree,Depth-first Search Medium
1316 Distinct Echo Substrings String Hard
1317 Convert Integer to the Sum of Two No-Zero Integers Math Easy
1318 Minimum Flips to Make a OR b Equal to c Bit Manipulation Medium
1319 Number of Operations to Make Network Connected Depth-first Search,Breadth-first Search,Union Find Medium
1320 Minimum Distance to Type a Word Using Two Fingers Dynamic Programming Hard
1321 Restaurant Growth Medium 🔒
1322 Ads Performance Easy 🔒
1323 Maximum 69 Number Math Easy
1324 Print Words Vertically String Medium
1325 Delete Leaves With a Given Value Tree Medium
1326 Minimum Number of Taps to Open to Water a Garden Greedy,Dynamic Programming Hard
1327 List the Products Ordered in a Period Easy 🔒
1328 Break a Palindrome String Medium
1329 Sort the Matrix Diagonally Sort,Array Medium
1330 Reverse Subarray To Maximize Array Value Array,Math Hard
1331 Rank Transform of an Array Array Easy
1332 Remove Palindromic Subsequences String Easy
1333 Filter Restaurants by Vegan-Friendly, Price and Distance Sort,Array Medium
1334 Find the City With the Smallest Number of Neighbors at a Threshold Distance Graph Medium
1335 Minimum Difficulty of a Job Schedule Dynamic Programming Hard
1336 Number of Transactions per Visit Hard 🔒
1337 The K Weakest Rows in a Matrix Array,Binary Search Easy
1338 Reduce Array Size to The Half Greedy,Array Medium
1339 Maximum Product of Splitted Binary Tree Tree,Dynamic Programming Medium
1340 Jump Game V Dynamic Programming Hard
1341 Movie Rating Medium 🔒
1342 Number of Steps to Reduce a Number to Zero Bit Manipulation Easy
1343 Number of Sub-arrays of Size K and Average Greater than or Equal to Threshold Array Medium
1344 Angle Between Hands of a Clock Math Medium
1345 Jump Game IV Breadth-first Search Hard
1346 Check If N and Its Double Exist Array Easy
1347 Minimum Number of Steps to Make Two Strings Anagram String Medium
1348 Tweet Counts Per Frequency Design Medium
1349 Maximum Students Taking Exam Dynamic Programming Hard
1350 Students With Invalid Departments Easy 🔒
1351 Count Negative Numbers in a Sorted Matrix Array,Binary Search Easy
1352 Product of the Last K Numbers Design,Array Medium
1353 Maximum Number of Events That Can Be Attended Greedy,Sort,Segment Tree Medium
1354 Construct Target Array With Multiple Sums Greedy Hard
1355 Activity Participants Medium 🔒
1356 Sort Integers by The Number of 1 Bits Sort,Bit Manipulation Easy
1357 Apply Discount Every n Orders Design Medium
1358 Number of Substrings Containing All Three Characters String Medium
1359 Count All Valid Pickup and Delivery Options Math,Dynamic Programming Hard
1360 Number of Days Between Two Dates Easy
1361 Validate Binary Tree Nodes Graph Medium
1362 Closest Divisors Math Medium
1363 Largest Multiple of Three Math,Dynamic Programming Hard
1364 Number of Trusted Contacts of a Customer Medium 🔒
1365 How Many Numbers Are Smaller Than the Current Number Array,Hash Table Easy
1366 Rank Teams by Votes Sort,Array Medium
1367 Linked List in Binary Tree Tree,Linked List,Dynamic Programming Medium
1368 Minimum Cost to Make at Least One Valid Path in a Grid Breadth-first Search Hard
1369 Get the Second Most Recent Activity Hard 🔒
1370 Increasing Decreasing String Sort,String Easy
1371 Find the Longest Substring Containing Vowels in Even Counts String Medium
1372 Longest ZigZag Path in a Binary Tree Tree,Dynamic Programming Medium
1373 Maximum Sum BST in Binary Tree Binary Search Tree,Dynamic Programming Hard
1374 Generate a String With Characters That Have Odd Counts String Easy
1375 Bulb Switcher III Array Medium
1376 Time Needed to Inform All Employees Depth-first Search Medium
1377 Frog Position After T Seconds Depth-first Search Hard
1378 Replace Employee ID With The Unique Identifier Easy 🔒
1379 Find a Corresponding Node of a Binary Tree in a Clone of That Tree Tree,Depth-first Search,Breadth-first Search,Recursion Medium
1380 Lucky Numbers in a Matrix Array Easy
1381 Design a Stack With Increment Operation Stack,Design Medium
1382 Balance a Binary Search Tree Binary Search Tree Medium
1383 Maximum Performance of a Team Greedy,Sort Hard
1384 Total Sales Amount by Year Hard 🔒
1385 Find the Distance Value Between Two Arrays Array Easy
1386 Cinema Seat Allocation Greedy,Array Medium
1387 Sort Integers by The Power Value Sort,Graph Medium
1388 Pizza With 3n Slices Dynamic Programming Hard
1389 Create Target Array in the Given Order Array Easy
1390 Four Divisors Math Medium
1391 Check if There is a Valid Path in a Grid Depth-first Search,Breadth-first Search Medium
1392 Longest Happy Prefix String Hard
1393 Capital GainLoss Medium 🔒
1394 Find Lucky Integer in an Array Array Easy
1395 Count Number of Teams Array Medium
1396 Design Underground System Design Medium
1397 Find All Good Strings Dynamic Programming Hard
1398 Customers Who Bought Products A and B but Not C Medium 🔒
1399 Count Largest Group Array Easy
1400 Construct K Palindrome Strings Greedy Medium
1401 Circle and Rectangle Overlapping Geometry Medium
1402 Reducing Dishes Dynamic Programming Hard
1403 Minimum Subsequence in Non-Increasing Order Greedy,Sort Easy
1404 Number of Steps to Reduce a Number in Binary Representation to One Bit Manipulation,String Medium
1405 Longest Happy String Greedy,Dynamic Programming Medium
1406 Stone Game III Dynamic Programming Hard
1407 Top Travellers Easy 🔒
1408 String Matching in an Array String Easy
1409 Queries on a Permutation With Key Array Medium
1410 HTML Entity Parser Stack,String Medium
1411 Number of Ways to Paint N × 3 Grid Dynamic Programming Hard
1412 Find the Quiet Students in All Exams Hard 🔒
1413 Minimum Value to Get Positive Step by Step Sum Array Easy
1414 Find the Minimum Number of Fibonacci Numbers Whose Sum Is K Greedy,Array Medium
1415 The k-th Lexicographical String of All Happy Strings of Length n Backtracking Medium
1416 Restore The Array Dynamic Programming Hard
1417 Reformat The String String Easy
1418 Display Table of Food Orders in a Restaurant Hash Table Medium
1419 Minimum Number of Frogs Croaking String Medium
1420 Build Array Where You Can Find The Maximum Exactly K Comparisons Dynamic Programming Hard
1421 NPV Queries Medium 🔒
1422 Maximum Score After Splitting a String String Easy
1423 Maximum Points You Can Obtain from Cards Array,Dynamic Programming,Sliding Window Medium
1424 Diagonal Traverse II Sort,Array Medium
1425 Constrained Subsequence Sum Dynamic Programming Hard
1426 Counting Elements Array Easy 🔒
1427 Perform String Shifts Array,Math Easy 🔒
1428 Leftmost Column with at Least a One Array Medium 🔒
1429 First Unique Number Design,Hash Table Medium 🔒
1430 Check If a String Is a Valid Sequence from Root to Leaves Path in a Binary Tree Tree Medium 🔒
1431 Kids With the Greatest Number of Candies Array Easy
1432 Max Difference You Can Get From Changing an Integer String Medium
1433 Check If a String Can Break Another String Greedy,String Medium
1434 Number of Ways to Wear Different Hats to Each Other Bit Manipulation,Dynamic Programming Hard
1435 Create a Session Bar Chart Easy 🔒
1436 Destination City String Easy
1437 Check If All 1's Are at Least Length K Places Away Array Easy
1438 Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit Array,Sliding Window Medium
1439 Find the Kth Smallest Sum of a Matrix With Sorted Rows Heap Hard
1440 Evaluate Boolean Expression Medium 🔒
1441 Build an Array With Stack Operations Stack Easy
1442 Count Triplets That Can Form Two Arrays of Equal XOR Bit Manipulation,Array,Math Medium
1443 Minimum Time to Collect All Apples in a Tree Tree,Depth-first Search Medium
1444 Number of Ways of Cutting a Pizza Dynamic Programming Hard
1445 Apples & Oranges Medium 🔒
1446 Consecutive Characters String Easy
1447 Simplified Fractions Math Medium
1448 Count Good Nodes in Binary Tree Tree,Depth-first Search Medium
1449 Form Largest Integer With Digits That Add up to Target String,Dynamic Programming Hard
1450 Number of Students Doing Homework at a Given Time Array Easy
1451 Rearrange Words in a Sentence Sort,String Medium
1452 People Whose List of Favorite Companies Is Not a Subset of Another List Sort,String Medium
1453 Maximum Number of Darts Inside of a Circular Dartboard Geometry Hard
1454 Active Users Medium 🔒
1455 Check If a Word Occurs As a Prefix of Any Word in a Sentence String Easy
1456 Maximum Number of Vowels in a Substring of Given Length String,Sliding Window Medium
1457 Pseudo-Palindromic Paths in a Binary Tree Bit Manipulation,Tree,Depth-first Search Medium
1458 Max Dot Product of Two Subsequences Dynamic Programming Hard
1459 Rectangles Area Medium 🔒
1460 Make Two Arrays Equal by Reversing Sub-arrays Array Easy
1461 Check If a String Contains All Binary Codes of Size K Bit Manipulation,String Medium
1462 Course Schedule IV Graph Medium
1463 Cherry Pickup II Dynamic Programming Hard
1464 Maximum Product of Two Elements in an Array Array Easy
1465 Maximum Area of a Piece of Cake After Horizontal and Vertical Cuts Array Medium
1466 Reorder Routes to Make All Paths Lead to the City Zero Tree,Depth-first Search Medium
1467 Probability of a Two Boxes Having The Same Number of Distinct Balls Math,Backtracking Hard
1468 Calculate Salaries Medium 🔒
1469 Find All The Lonely Nodes Tree,Depth-first Search Easy 🔒
1470 Shuffle the Array Array Easy
1471 The k Strongest Values in an Array Sort,Array Medium
1472 Design Browser History Design Medium
1473 Paint House III Dynamic Programming Hard
1474 Delete N Nodes After M Nodes of a Linked List Linked List Easy 🔒
1475 Final Prices With a Special Discount in a Shop Array Easy
1476 Subrectangle Queries Array Medium
1477 Find Two Non-overlapping Sub-arrays Each With Target Sum Dynamic Programming Medium
1478 Allocate Mailboxes Math,Dynamic Programming Hard
1479 Sales by Day of the Week Hard 🔒
1480 Running Sum of 1d Array Array Easy
1481 Least Number of Unique Integers after K Removals Sort,Array Medium
1482 Minimum Number of Days to Make m Bouquets Array,Binary Search Medium
1483 Kth Ancestor of a Tree Node Dynamic Programming Hard
1484 Group Sold Products By The Date Easy 🔒
1485 Clone Binary Tree With Random Pointer Tree,Depth-first Search Medium 🔒
1486 XOR Operation in an Array Bit Manipulation,Array Easy
1487 Making File Names Unique Hash Table,String Medium
1488 Avoid Flood in The City Array,Hash Table Medium
1489 Find Critical and Pseudo-Critical Edges in Minimum Spanning Tree Depth-first Search,Union Find Hard
1490 Clone N-ary Tree Tree,Depth-first Search,Breadth-first Search,Hash Table Medium 🔒
1491 Average Salary Excluding the Minimum and Maximum Salary Sort,Array Easy
1492 The kth Factor of n Math Medium
1493 Longest Subarray of 1's After Deleting One Element Array Medium
1494 Parallel Courses II Graph Hard
1495 Friendly Movies Streamed Last Month Easy 🔒
1496 Path Crossing String Easy
1497 Check If Array Pairs Are Divisible by k Greedy,Array,Math Medium
1498 Number of Subsequences That Satisfy the Given Sum Condition Sort,Sliding Window Medium
1499 Max Value of Equation Array,Sliding Window Hard
1500 Design a File Sharing System Design,Array Medium 🔒
1501 Countries You Can Safely Invest In Medium 🔒
1502 Can Make Arithmetic Progression From Sequence Sort,Array Easy
1503 Last Moment Before All Ants Fall Out of a Plank Brainteaser,Array Medium
1504 Count Submatrices With All Ones Dynamic Programming Medium
1505 Minimum Possible Integer After at Most K Adjacent Swaps On Digits Greedy Hard
1506 Find Root of N-Ary Tree Medium 🔒
1507 Reformat Date String Easy
1508 Range Sum of Sorted Subarray Sums Sort,Array Medium
1509 Minimum Difference Between Largest and Smallest Value in Three Moves Sort,Array Medium
1510 Stone Game IV Dynamic Programming Hard
1511 Customer Order Frequency Easy 🔒
1512 Number of Good Pairs Array,Hash Table,Math Easy
1513 Number of Substrings With Only 1s Math,String Medium
1514 Path with Maximum Probability Graph Medium
1515 Best Position for a Service Centre Geometry Hard
1516 Move Sub-Tree of N-Ary Tree Tree Hard 🔒
1517 Find Users With Valid E-Mails Easy 🔒
1518 Water Bottles Greedy Easy
1519 Number of Nodes in the Sub-Tree With the Same Label Depth-first Search,Breadth-first Search Medium
1520 Maximum Number of Non-Overlapping Substrings Greedy Hard
1521 Find a Value of a Mysterious Function Closest to Target Bit Manipulation,Segment Tree,Binary Search Hard
1522 Diameter of N-Ary Tree Medium 🔒
1523 Count Odd Numbers in an Interval Range Math Easy
1524 Number of Sub-arrays With Odd Sum Array,Math Medium
1525 Number of Good Ways to Split a String Bit Manipulation,String Medium
1526 Minimum Number of Increments on Subarrays to Form a Target Array Segment Tree Hard
1527 Patients With a Condition Easy 🔒
1528 Shuffle String Sort Easy
1529 Bulb Switcher IV String Medium
1530 Number of Good Leaf Nodes Pairs Tree,Depth-first Search Medium
1531 String Compression II String,Dynamic Programming Hard
1532 The Most Recent Three Orders Medium 🔒
1533 Find the Index of the Large Integer Binary Search Medium 🔒
1534 Count Good Triplets Array Easy
1535 Find the Winner of an Array Game Array Medium
1536 Minimum Swaps to Arrange a Binary Grid Greedy Medium
1537 Get the Maximum Score Dynamic Programming Hard
1538 Guess the Majority in a Hidden Array Medium 🔒
1539 Kth Missing Positive Number Array,Hash Table Easy
1540 Can Convert String in K Moves Greedy,String Medium
1541 Minimum Insertions to Balance a Parentheses String Stack,String Medium
1542 Find Longest Awesome Substring Bit Manipulation,String Hard
1543 Fix Product Name Format Easy 🔒
1544 Make The String Great Stack,String Easy
1545 Find Kth Bit in Nth Binary String String Medium
1546 Maximum Number of Non-Overlapping Subarrays With Sum Equals Target Dynamic Programming Medium
1547 Minimum Cost to Cut a Stick Dynamic Programming Hard
1548 The Most Similar Path in a Graph Graph,Dynamic Programming Hard 🔒
1549 The Most Recent Orders for Each Product Medium 🔒
1550 Three Consecutive Odds Array Easy
1551 Minimum Operations to Make Array Equal Math Medium
1552 Magnetic Force Between Two Balls Array,Binary Search Medium
1553 Minimum Number of Days to Eat N Oranges Dynamic Programming Hard
1554 Strings Differ by One Character Medium 🔒
1555 Bank Account Summary Medium 🔒
1556 Thousand Separator String Easy
1557 Minimum Number of Vertices to Reach All Nodes Graph Medium
1558 Minimum Numbers of Function Calls to Make Target Array Greedy Medium
1559 Detect Cycles in 2D Grid Depth-first Search Hard
1560 Most Visited Sector in a Circular Track Array Easy
1561 Maximum Number of Coins You Can Get Sort Medium
1562 Find Latest Group of Size M Binary Search Medium
1563 Stone Game V Dynamic Programming Hard
1564 Put Boxes Into the Warehouse I Greedy Medium 🔒
1565 Unique Orders and Customers Per Month Easy 🔒
1566 Detect Pattern of Length M Repeated K or More Times Array Easy
1567 Maximum Length of Subarray With Positive Product Greedy Medium
1568 Minimum Number of Days to Disconnect Island Greedy Hard
1569 Number of Ways to Reorder Array to Get Same BST Dynamic Programming Hard
1570 Dot Product of Two Sparse Vectors Array,Hash Table,Two Pointers Medium 🔒
1571 Warehouse Manager Easy 🔒
1572 Matrix Diagonal Sum Array Easy
1573 Number of Ways to Split a String String Medium
1574 Shortest Subarray to be Removed to Make Array Sorted Array,Binary Search Medium
1575 Count All Possible Routes Dynamic Programming Hard
1576 Replace All 's to Avoid Consecutive Repeating Characters String Easy
1577 Number of Ways Where Square of Number Is Equal to Product of Two Numbers Hash Table,Math Medium
1578 Minimum Deletion Cost to Avoid Repeating Letters Greedy Medium
1579 Remove Max Number of Edges to Keep Graph Fully Traversable Union Find Hard
1580 Put Boxes Into the Warehouse II Greedy Medium 🔒
1581 Customer Who Visited but Did Not Make Any Transactions Easy 🔒
1582 Special Positions in a Binary Matrix Array Easy
1583 Count Unhappy Friends Array Medium
1584 Min Cost to Connect All Points Union Find Medium
1585 Check If String Is Transformable With Substring Sort Operations Greedy,String Hard
1586 Binary Search Tree Iterator II Tree,Design Medium 🔒
1587 Bank Account Summary II Easy 🔒
1588 Sum of All Odd Length Subarrays Array Easy
1589 Maximum Sum Obtained of Any Permutation Greedy Medium
1590 Make Sum Divisible by P Array,Hash Table,Math,Binary Search Medium
1591 Strange Printer II Greedy Hard
1592 Rearrange Spaces Between Words String Easy
1593 Split a String Into the Max Number of Unique Substrings Backtracking Medium
1594 Maximum Non Negative Product in a Matrix Greedy,Dynamic Programming Medium
1595 Minimum Cost to Connect Two Groups of Points Graph,Dynamic Programming Hard
1596 The Most Frequently Ordered Products for Each Customer Medium 🔒
1597 Build Binary Expression Tree From Infix Expression Tree,String Hard 🔒
1598 Crawler Log Folder Stack Easy
1599 Maximum Profit of Operating a Centennial Wheel Greedy Medium
1600 Throne Inheritance Tree,Design Medium
1601 Maximum Number of Achievable Transfer Requests Dynamic Programming Hard
1602 Find Nearest Right Node in Binary Tree Tree,Breadth-first Search Medium 🔒
1603 Design Parking System Design Easy
1604 Alert Using Same Key-Card Three or More Times in a One Hour Period String,Ordered Map Medium
1605 Find Valid Matrix Given Row and Column Sums Greedy Medium
1606 Find Servers That Handled Most Number of Requests Ordered Map Hard
1607 Sellers With No Sales Easy 🔒
1608 Special Array With X Elements Greater Than or Equal X Array Easy
1609 Even Odd Tree Tree Medium
1610 Maximum Number of Visible Points Geometry,Two Pointers Hard
1611 Minimum One Bit Operations to Make Integers Zero Bit Manipulation,Dynamic Programming Hard
1612 Check If Two Expression Trees are Equivalent Tree,Hash Table Medium 🔒
1613 Find the Missing IDs Medium 🔒
1614 Maximum Nesting Depth of the Parentheses String Easy
1615 Maximal Network Rank Graph Medium
1616 Split Two Strings to Make Palindrome Greedy,Two Pointers,String Medium
1617 Count Subtrees With Max Distance Between Cities Backtracking Hard
1618 Maximum Font to Fit a Sentence in a Screen String,Binary Search Medium 🔒
1619 Mean of Array After Removing Some Elements Array Easy
1620 Coordinate With Maximum Network Quality Greedy Medium
1621 Number of Sets of K Non-Overlapping Line Segments Dynamic Programming Medium
1622 Fancy Sequence Design,Math Hard
1623 All Valid Triplets That Can Represent a Country Easy 🔒
1624 Largest Substring Between Two Equal Characters String Easy
1625 Lexicographically Smallest String After Applying Operations Depth-first Search,Breadth-first Search Medium
1626 Best Team With No Conflicts Dynamic Programming Medium
1627 Graph Connectivity With Threshold Union Find,Math Hard
1628 Design an Expression Tree With Evaluate Function Tree,Design Medium 🔒
1629 Slowest Key Array Easy
1630 Arithmetic Subarrays Sort Medium
1631 Path With Minimum Effort Depth-first Search,Union Find,Graph,Binary Search Medium
1632 Rank Transform of a Matrix Greedy,Union Find Hard
1633 Percentage of Users Attended a Contest Easy 🔒
1634 Add Two Polynomials Represented as Linked Lists Linked List Medium 🔒
1635 Hopper Company Queries I Hard 🔒
1636 Sort Array by Increasing Frequency Sort,Array Easy
1637 Widest Vertical Area Between Two Points Containing No Points Sort Medium
1638 Count Substrings That Differ by One Character Trie,Hash Table,String Medium
1639 Number of Ways to Form a Target String Given a Dictionary Dynamic Programming Hard
1640 Check Array Formation Through Concatenation Sort,Array,Hash Table Easy
1641 Count Sorted Vowel Strings Math,Dynamic Programming,Backtracking Medium
1642 Furthest Building You Can Reach Heap,Binary Search Medium
1643 Kth Smallest Instructions Dynamic Programming Hard
1644 Lowest Common Ancestor of a Binary Tree II Tree Medium 🔒
1645 Hopper Company Queries II Hard 🔒
1646 Get Maximum in Generated Array Array Easy
1647 Minimum Deletions to Make Character Frequencies Unique Greedy,Sort Medium
1648 Sell Diminishing-Valued Colored Balls Greedy,Sort,Math Medium
1649 Create Sorted Array through Instructions Binary Indexed Tree,Segment Tree,Binary Search,Ordered Map Hard
1650 Lowest Common Ancestor of a Binary Tree III Tree Medium 🔒
1651 Hopper Company Queries III Hard 🔒
1652 Defuse the Bomb Array Easy
1653 Minimum Deletions to Make String Balanced Greedy,String Medium
1654 Minimum Jumps to Reach Home Breadth-first Search,Dynamic Programming Medium
1655 Distribute Repeating Integers Dynamic Programming,Backtracking Hard
1656 Design an Ordered Stream Design,Array Easy
1657 Determine if Two Strings Are Close Greedy Medium
1658 Minimum Operations to Reduce X to Zero Greedy,Two Pointers,Binary Search,Sliding Window Medium
1659 Maximize Grid Happiness Dynamic Programming,Backtracking Hard
1660 Correct a Binary Tree Tree Medium 🔒
1661 Average Time of Process per Machine Easy 🔒
1662 Check If Two String Arrays are Equivalent String Easy
1663 Smallest String With A Given Numeric Value Greedy Medium
1664 Ways to Make a Fair Array Greedy,Dynamic Programming Medium
1665 Minimum Initial Energy to Finish Tasks Greedy Hard
1666 Change the Root of a Binary Tree Tree,Depth-first Search Medium 🔒
1667 Fix Names in a Table Easy 🔒
1668 Maximum Repeating Substring String Easy
1669 Merge In Between Linked Lists Linked List Medium
1670 Design Front Middle Back Queue Design,Linked List Medium
1671 Minimum Number of Removals to Make Mountain Array Dynamic Programming Hard
1672 Richest Customer Wealth Array Easy
1673 Find the Most Competitive Subsequence Stack,Heap,Greedy,Queue Medium
1674 Minimum Moves to Make Array Complementary Greedy Medium
1675 Minimize Deviation in Array Heap,Ordered Map Hard
1676 Lowest Common Ancestor of a Binary Tree IV Tree,Depth-first Search Medium 🔒
1677 Product's Worth Over Invoices Easy 🔒
1678 Goal Parser Interpretation String Easy
1679 Max Number of K-Sum Pairs Hash Table Medium
1680 Concatenation of Consecutive Binary Numbers Math Medium
1681 Minimum Incompatibility Greedy,Backtracking Hard
1682 Longest Palindromic Subsequence II String,Dynamic Programming Medium 🔒
1683 Invalid Tweets Easy 🔒
1684 Count the Number of Consistent Strings String Easy
1685 Sum of Absolute Differences in a Sorted Array Greedy,Math Medium
1686 Stone Game VI Greedy Medium
1687 Delivering Boxes from Storage to Ports Segment Tree,Two Pointers,Dynamic Programming Hard
1688 Count of Matches in Tournament Backtracking Easy
1689 Partitioning Into Minimum Number Of Deci-Binary Numbers Greedy Medium
1690 Stone Game VII Dynamic Programming Medium
1691 Maximum Height by Stacking Cuboids Sort,Dynamic Programming Hard
1692 Count Ways to Distribute Candies Dynamic Programming Hard 🔒
1693 Daily Leads and Partners Easy 🔒
1694 Reformat Phone Number String Easy
1695 Maximum Erasure Value Two Pointers Medium
1696 Jump Game VI Medium
1697 Checking Existence of Edge Length Limited Paths Sort,Union Find Hard
1698 Number of Distinct Substrings in a String Trie,String Medium 🔒
1699 Number of Calls Between Two Persons Medium 🔒
1700 Number of Students Unable to Eat Lunch Array Easy
1701 Average Waiting Time Array Medium
1702 Maximum Binary String After Change Greedy Medium
1703 Minimum Adjacent Swaps for K Consecutive Ones Stack Hard
1704 Determine if String Halves Are Alike String Easy
1705 Maximum Number of Eaten Apples Heap,Greedy Medium
1706 Where Will the Ball Fall Dynamic Programming Medium
1707 Maximum XOR With an Element From Array Bit Manipulation,Trie Hard
1708 Largest Subarray Length K Greedy,Array Easy 🔒
1709 Biggest Window Between Visits Medium 🔒
1710 Maximum Units on a Truck Greedy,Sort Easy
1711 Count Good Meals Array,Hash Table,Two Pointers Medium
1712 Ways to Split Array Into Three Subarrays Two Pointers,Binary Search Medium
1713 Minimum Operations to Make a Subsequence Greedy Hard
1714 Sum Of Special Evenly-Spaced Elements In Array Hard 🔒
1715 Count Apples and Oranges Medium 🔒
1716 Calculate Money in Leetcode Bank Greedy,Math Easy
1717 Maximum Score From Removing Substrings Greedy Medium
1718 Construct the Lexicographically Largest Valid Sequence Recursion,Backtracking Medium
1719 Number Of Ways To Reconstruct A Tree Tree,Graph Hard
1720 Decode XORed Array Bit Manipulation Easy
1721 Swapping Nodes in a Linked List Linked List Medium
1722 Minimize Hamming Distance After Swap Operations Greedy,Depth-first Search,Union Find Medium
1723 Find Minimum Time to Finish All Jobs Recursion,Backtracking Hard
1724 Checking Existence of Edge Length Limited Paths II Union Find,Graph,Dynamic Programming Hard 🔒
1725 Number Of Rectangles That Can Form The Largest Square Greedy Easy
1726 Tuple with Same Product Array,Hash Table Medium
1727 Largest Submatrix With Rearrangements Greedy,Sort Medium
1728 Cat and Mouse II Dynamic Programming Hard
1729 Find Followers Count Easy 🔒
1730 Shortest Path to Get Food Depth-first Search,Breadth-first Search,Graph Medium 🔒
1731 The Number of Employees Which Report to Each Employee Easy 🔒
1732 Find the Highest Altitude Array Easy
1733 Minimum Number of People to Teach Greedy,Array Medium
1734 Decode XORed Permutation Bit Manipulation Medium
1735 Count Ways to Make Array With Product Math Hard
1736 Latest Time by Replacing Hidden Digits Greedy,String Easy
1737 Change Minimum Characters to Satisfy One of Three Conditions Greedy,String Medium
1738 Find Kth Largest XOR Coordinate Value Array Medium
1739 Building Boxes Math,Binary Search Hard
1740 Find Distance in a Binary Tree Tree,Depth-first Search,Breadth-first Search Medium 🔒
1741 Find Total Time Spent by Each Employee Easy 🔒
1742 Maximum Number of Balls in a Box Array Easy
1743 Restore the Array From Adjacent Pairs Greedy Medium
1744 Can You Eat Your Favorite Candy on Your Favorite Day Math Medium
1745 Palindrome Partitioning IV String,Dynamic Programming Hard
1746 Maximum Subarray Sum After One Operation Dynamic Programming Medium 🔒
1747 Leetflex Banned Accounts Medium 🔒
1748 Sum of Unique Elements Array,Hash Table Easy
1749 Maximum Absolute Sum of Any Subarray Greedy Medium
1750 Minimum Length of String After Deleting Similar Ends Two Pointers Medium
1751 Maximum Number of Events That Can Be Attended II Binary Search,Dynamic Programming Hard
1752 Check if Array Is Sorted and Rotated Array Easy
1753 Maximum Score From Removing Stones Heap,Math Medium
1754 Largest Merge Of Two Strings Greedy Medium
1755 Closest Subsequence Sum Divide and Conquer Hard
1756 Design Most Recently Used Queue Design,Array Medium 🔒
1757 Recyclable and Low Fat Products Easy 🔒
1758 Minimum Changes To Make Alternating Binary String Greedy,Array Easy
1759 Count Number of Homogenous Substrings Greedy,String Medium
1760 Minimum Limit of Balls in a Bag Heap,Binary Search Medium
1761 Minimum Degree of a Connected Trio in a Graph Graph Hard
1762 Buildings With an Ocean View Greedy Medium 🔒
1763 Longest Nice Substring String Easy
1764 Form Array by Concatenating Subarrays of Another Array Greedy,Array Medium
1765 Map of Highest Peak Breadth-first Search,Graph Medium
1766 Tree of Coprimes Tree,Depth-first Search,Breadth-first Search,Math Hard
1767 Find the Subtasks That Did Not Execute Hard 🔒
1768 Merge Strings Alternately String Easy
1769 Minimum Number of Operations to Move All Balls to Each Box Greedy,Array Medium
1770 Maximum Score from Performing Multiplication Operations Dynamic Programming Medium
1771 Maximize Palindrome Length From Subsequences Dynamic Programming Hard
1772 Sort Features by Popularity Sort,Hash Table Medium 🔒
1773 Count Items Matching a Rule Array,String Easy
1774 Closest Dessert Cost Greedy Medium
1775 Equal Sum Arrays With Minimum Number of Operations Greedy Medium
1776 Car Fleet II Math Hard
1777 Product's Price for Each Store Easy 🔒
1778 Shortest Path in a Hidden Grid Depth-first Search,Breadth-first Search,Graph Medium 🔒
1779 Find Nearest Point That Has the Same X or Y Coordinate Array Easy
1780 Check if Number is a Sum of Powers of Three Recursion,Math,Backtracking Medium
1781 Sum of Beauty of All Substrings Hash Table,String Medium
1782 Count Pairs Of Nodes Graph Hard
1783 Grand Slam Titles Medium 🔒
1784 Check if Binary String Has at Most One Segment of Ones Greedy Easy
1785 Minimum Elements to Add to Form a Given Sum Greedy Medium
1786 Number of Restricted Paths From First to Last Node Graph,Dynamic Programming Medium
1787 Make the XOR of All Segments Equal to Zero Dynamic Programming Hard
1788 Maximize the Beauty of the Garden Greedy Hard 🔒
1789 Primary Department for Each Employee Easy 🔒
1790 Check if One String Swap Can Make Strings Equal String Easy
1791 Find Center of Star Graph Graph Medium
1792 Maximum Average Pass Ratio Heap Medium
1793 Maximum Score of a Good Subarray Greedy Hard
1794 Count Pairs of Equal Substrings With Minimum Difference Greedy,String Medium 🔒
1795 Rearrange Products Table Easy 🔒
1796 Second Largest Digit in a String String Easy
1797 Design Authentication Manager Design,Hash Table Medium
1798 Maximum Number of Consecutive Values You Can Make Greedy Medium
1799 Maximize Score After N Operations Recursion,Dynamic Programming,Backtracking Hard
1800 Maximum Ascending Subarray Sum Two Pointers Easy
1801 Number of Orders in the Backlog Heap,Greedy Medium
1802 Maximum Value at a Given Index in a Bounded Array Greedy,Binary Search Medium
1803 Count Pairs With XOR in a Range Trie Hard
1804 Implement Trie II (Prefix Tree) Trie,String Medium 🔒
1805 Number of Different Integers in a String String Easy
1806 Minimum Number of Operations to Reinitialize a Permutation Greedy,Array Medium
1807 Evaluate the Bracket Pairs of a String Hash Table,String Medium
1808 Maximize Number of Nice Divisors Math Hard
1809 Ad-Free Sessions Easy 🔒
1810 Minimum Path Cost in a Hidden Grid Heap,Depth-first Search,Graph Medium 🔒
1811 Find Interview Candidates Medium 🔒
1812 Determine Color of a Chessboard Square String Easy
1813 Sentence Similarity III String Medium
1814 Count Nice Pairs in an Array Array,Hash Table Medium
1815 Maximum Number of Groups Getting Fresh Donuts Dynamic Programming Hard
1816 Truncate Sentence String Easy
1817 Finding the Users Active Minutes Hash Table Medium
1818 Minimum Absolute Sum Difference Greedy,Binary Search Medium
1819 Number of Different Subsequences GCDs Math Hard
1820 Maximum Number of Accepted Invitations Graph Medium 🔒
1821 Find Customers With Positive Revenue this Year Easy 🔒
1822 Sign of the Product of an Array Math Easy
1823 Find the Winner of the Circular Game Array Medium
1824 Minimum Sideway Jumps Breadth-first Search,Dynamic Programming Medium
1825 Finding MK Average Heap,Design,Queue Hard
1826 Faulty Sensor Array Easy 🔒
1827 Minimum Operations to Make the Array Increasing Greedy,Array Easy
1828 Queries on Number of Points Inside a Circle Math Medium
1829 Maximum XOR for Each Query Bit Manipulation Medium
1830 Minimum Number of Operations to Make String Sorted Math,String Hard
1831 Maximum Transaction Each Day Medium 🔒
1832 Check if the Sentence Is Pangram String Easy
1833 Maximum Ice Cream Bars Sort,Array Medium
1834 Single-Threaded CPU Heap Medium
1835 Find XOR Sum of All Pairs Bitwise AND Math Hard
1836 Remove Duplicates From an Unsorted Linked List Linked List Medium 🔒
1837 Sum of Digits in Base K Bit Manipulation,Math Easy
1838 Frequency of the Most Frequent Element Greedy Medium
1839 Longest Substring Of All Vowels in Order Two Pointers,String Medium
1840 Maximum Building Height Greedy,Binary Search Hard
1841 League Statistics Medium 🔒
1842 Next Palindrome Using Same Digits Greedy Hard 🔒
1843 Suspicious Bank Accounts Medium 🔒
1844 Replace All Digits with Characters String Easy
1845 Seat Reservation Manager Heap,Design Medium
1846 Maximum Element After Decreasing and Rearranging Greedy,Sort Medium
1847 Closest Room Sort,Binary Search Hard
1848 Minimum Distance to the Target Element Array Easy
1849 Splitting a String Into Descending Consecutive Values Recursion,String,Backtracking Medium
1850 Minimum Adjacent Swaps to Reach the Kth Smallest Number Greedy,String Medium
1851 Minimum Interval to Include Each Query Line Sweep Hard
1852 Distinct Numbers in Each Subarray Array,Hash Table,Line Sweep Medium 🔒
1853 Convert Date Format Easy 🔒
1854 Maximum Population Year Array Easy
1855 Maximum Distance Between a Pair of Values Greedy,Two Pointers,Binary Search Medium
1856 Maximum Subarray Min-Product Sort,Union Find,Queue,Binary Search,Dynamic Programming Medium
1857 Largest Color Value in a Directed Graph Topological Sort,Dynamic Programming Hard
1858 Longest Word With All Prefixes Depth-first Search,Trie,Hash Table Medium 🔒
1859 Sorting the Sentence Sort,String Easy
1860 Incremental Memory Leak Math Medium
1861 Rotating the Box Array,Two Pointers Medium
1862 Sum of Floored Pairs Math Hard
1863 Sum of All Subset XOR Totals Recursion,Backtracking Easy
1864 Minimum Number of Swaps to Make the Binary String Alternating Greedy Medium
1865 Finding Pairs With a Certain Sum Design,Hash Table,Ordered Map Medium
1866 Number of Ways to Rearrange Sticks With K Sticks Visible Dynamic Programming Hard

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