Index¶

• 1 Two Sum – Medium
• 2 Add Two Numbers – Medium
• 3 Longest Substring Without Repeating Characters
• 4 Median of Two Sorted Arrays
• 5 Longest Palindromic Substring
• 6 ZigZag Conversion – Easy
• 7 Reverse Integer – Easy
• 8 String to Integer (atoi) – Easy
• 9 Palindrome Number – Easy
• 10 Regular Expression Matching
• 11 Container With Most Water – Medium
• 12 Integer to Roman – Medium
• 13 Roman to Integer – Easy
• 14 Longest Common Prefix – Easy
• 15 3Sum – Medium
• 16 3Sum Closest – Medium
• 17 Letter Combinations of a Phone Number – Medium
• 18 4Sum – Medium
• 19 Remove Nth Node From End of List – Easy
• 20 Valid Parentheses – Easy
• 21 Merge Two Sorted Lists – Easy
• 22 Generate Parentheses – Medium
• 23 Merge k Sorted Lists
• 24 Swap Nodes in Pairs – Medium
• 25 Reverse Nodes in k-Group
• 26 Remove Duplicates from Sorted Array – Easy
• 27 Remove Element – Easy
• 28 Implement strStr() – Easy
• 29 Divide Two Integers – Medium
• 31 Next Permutation – Medium
• 33 Search in Rotated Sorted Array – Hard
• 34 Search for a Range – Medium
• 35 Search Insert Position – Medium
• 36 Valid Sudoku – Easy
• 37 Sudoku Solver
• 38 Count and Say – Easy
• 39 Combination Sum – Medium
• 40 Combination Sum II – Medium
• 42 Trapping Rain Water
• 43 Multiply Strings – Medium
• 44 Wildcard Matching
• 46 Permutations – Medium
• 47 Permutations II – Medium
• 48 Rotate Image – Medium
• 49 Group Anagrams – Medium
• 50 Pow(x, n) – Medium
• 53 Maximum Subarray – Medium
• 54 Spiral Matrix – Medium
• 55 Jump Game – Medium
• 56 Merge Intervals
• 57 Insert Interval
• 58 Length of Last Word – Easy
• 59 Spiral Matrix II – Medium
• 60 Permutation Sequence – Medium
• 61 Rotate List – Medium
• 62 Unique Paths – Medium
• 63 Unique Paths II – Medium
• 64 Minimum Path Sum – Medium
• 65 Valid Number
• 66 Plus One – Easy
• 67 Add Binary – Easy
• 68 Text Justification
• 69 Sqrt(x) – Medium
• 70 Climbing Stairs – Easy
• 71 Simplify Path – Medium
• 73 Set Matrix Zeroes – Medium
• 74 Search a 2D Matrix – Medium
• 75 Sort Colors – Medium
• 76 Minimum Window Substring
• 77 Combinations – Medium
• 78 Subsets – Medium
• 79 Word Search – Medium
• 80 Remove Duplicates from Sorted Array II – Medium
• 81 Search in Rotated Sorted Array II
• 82 Remove Duplicates from Sorted List II – Medium
• 83 Remove Duplicates from Sorted List – Easy
• 85 Maximal Rectangle
• 86 Partition List – Medium
• 88 Merge Sorted Array
• 89 Gray Code – Medium
• 90 Subsets II – Medium
• 91 Decode Ways – Medium
• 92 Reverse Linked List II – Medium
• 93 Restore IP Addresses – Medium
• 94 Binary Tree Inorder Traversal – Medium
• 95 Unique Binary Search Trees II – Medium
• 98 Validate Binary Search Tree
• 101 Symmetric Tree – Easy
• 102 Binary Tree Level Order Traversal – Easy
• 103 Binary Tree Zigzag Level Order Traversal
• 104 Maximum Depth of Binary Tree – Easy
• 105 Construct Binary Tree from Preorder and Inorder Traversal –
• Medium
• 106 Construct Binary Tree from Inorder and Postorder Traversal –
• Medium
• 107 Binary Tree Level Order Traversal II – Easy
• 108 Convert Sorted Array to Binary Search Tree – Medium
• 109 Convert Sorted List to Binary Search Tree – Medium
• 110 Balanced Binary Tree – Easy
• 111Minimum Depth of Binary Tree – Easy
• 112 Path Sum – Easy
• 113 Path Sum II – Medium
• 114 Flatten Binary Tree to Linked List – Medium
• 116 Populating Next Right Pointers in Each Node – Medium
• 117 Populating Next Right Pointers in Each Node II
• 118 Pascal’s Triangle – Easy
• 119 Pascal’s Triangle II – Medium
• 120 Triangle – Medium
• 121 Best Time to Buy and Sell Stock – Medium
• 122 Best Time to Buy and Sell Stock II – Medium
• 123 Best Time to Buy and Sell Stock III – Hard
• 125 Valid Palindrome – Easy
• 127 Word Ladder – Medium
• 128 Longest Consecutive Sequence
• 129 Sum Root to Leaf Numbers – Medium
• 130 Surrounded Regions – Medium
• 131 Palindrome Partitioning – Medium
• 132 Palindrome Partitioning II – Hard
• 133 Clone Graph – Medium
• 134 Gas Station – Medium
• 136 Single Number – Medium
• 137 Single Number II – Medium
• 138 Copy List with Random Pointer
• 139 Word Break – Medium
• 140 Word Break II – Hard
• 141 Linked List Cycle – Medium
• 142 Linked List Cycle II – Medium
• 143 Reorder List – Medium
• 144 Binary Tree Preorder Traversal – Medium
• 145 Binary Tree Postorder Traversal – Hard
• 146 LRU Cache – Hard
• 147 Insertion Sort List – Medium
• 148 Sort List
• 149 Max Points on a Line
• 150 Evaluate Reverse Polish Notation – Medium
• 151 Reverse Words in a String – Medium
• 152 Maximum Product Subarray – Medium
• 153 Find Minimum in Rotated Sorted Array – Medium
• 155 Min Stack – Easy
• 156 Binary Tree Upside Down – Medium
• 157 Read N Characters Given Read4 – Easy
• 158 Read N Characters Given Read4 II – Call multiple times Add to List QuestionEditorial Solution – Hard
• 159 Longest Substring with At Most Two Distinct Characters
• 160 Intersection of Two Linked Lists – Easy
• 161 One Edit Distance – Medium
• 162 Find Peak Element – Medium
• 163 Missing Ranges
• 165 Compare Version Numbers
• 166 Fraction to Recurring Decimal
• 167 Two Sum II – Input array is sorted – Medium
• 168 Excel Sheet Column Title – Easy
• 169 Majority Element – Easy
• 170 Two Sum III – Data structure design – Easy
• 171 Excel Sheet Column Number – Easy
• 172 Factorial Trailing Zeroes – Easy
• 173 Binary Search Tree Iterator – Medium
• 179 Largest Number – Medium
• 186 Reverse Words in a String II – Medium
• 187 Repeated DNA Sequences – Medium
• 189 Rotate Array – Easy
• 190 Java: Reverse Bits – Easy
• 191 Number of 1 Bits – Easy
• 198 House Robber – Easy
• 199 Binary Tree Right Side View – Medium
• 200 Number of Islands – Medium
• 201 LeetCode Java : Bitwise AND of Numbers Range – Medium
• 202 LeetCode Java: Happy Number – Easy
• 203 LeetCode Java: Remove Linked List Elements – Easy
• 204 LeetCode Java: Count Primes – Easy
• 205 LeetCode Java: Isomorphic Strings – Easy
• 206 LeetCode Java: Reverse Linked List -Easy
• 207 LeetCode Java: Course Schedule – Medium
• 208 LeetCode Java: Implement Trie (Prefix Tree) – Medium
• 209 LeetCode Java : Minimum Size Subarray Sum – Medium
• 210 LeetCode Java: Course Schedule II – Medium
• 211 LeetCode Java: Add and Search Word – Data structure design –
• Medium
• 212 Word Search II
• 213 House Robber II – Medium
• 214 Shortest Palindrome
• 215 Kth Largest Element in an Array – Medium
• 216 Combination Sum III – Medium
• 217 Contains Duplicate – Easy
• 218 The Skyline Problem
• 219 Contains Duplicate II – Medium
• 220 Contains Duplicate III – Medium
• 221 Maximal Square – Medium
• 222 Count Complete Tree Nodes – Medium
• 223 Rectangle Area – Easy
• 224 Basic Calculator
• 225 Implement Stack using Queues – Easy
• 226 Invert Binary Tree – Easy
• 227 Basic Calculator II – Medium
• 228 Summary Ranges – Medium
• 229 Majority Element II – Medium
• 230 Kth Smallest Element in a BST – Medium
• 231 Power of Two – Easy
• 232 Implement Queue using Stacks – Easy
• 234 Palindrome Linked List – Easy
• 235 Lowest Common Ancestor of a Binary Search Tree – Easy
• 236 Lowest Common Ancestor of a Binary Tree – Medium
• 237 Delete Node in a Linked List – Easy
• 238 Product of Array Except Self – Medium
• 239 Sliding Window Maximum
• 240 Search a 2D Matrix II – Medium
• 241 Different Ways to Add Parentheses – Medium
• 242 Valid Anagram – Easy
• 243 Shortest Word Distance – Easy
• 244 Shortest Word Distance II – Medium
• 245 Shortest Word Distance III – Medium
• 246 Strobogrammatic Number – Easy
• 247 Strobogrammatic Number II
• 248 LeetCode Java: Different Ways to Add Parentheses – Hard
• 249 LeetCode Java: Group Shifted Strings – Easy
• 250 LeetCode Java: Count Univalue Subtrees – Medium
• 251 Flatten 2D Vector
• 252 LeetCode Java: Meeting Rooms – Easy
• 253 Meeting Rooms II - Medium
• 254 Factor Combinations - Medium
• 255 Verify Preorder Sequence in Binary Search Tree - Medium
• 256 Paint House - Medium
• 257 Binary Tree Paths - Easy
• 258 Add Digits - Easy
• 259 3Sum Smaller
• 260 Single Number III
• 261 Graph Valid Tree
• 263 Ugly Number
• 264 Ugly Number II
• 266 Palindrome Permutation
• 267 Palindrome Permutation II
• 268 Missing Number
• 269 Alien Dictionary
• 270 Closest Binary Search Tree Value
• 271 Encode and Decode Strings
• 272 Closest Binary Search Tree Value II
• 273 Integer to English Words
• 274 H-Index
• 275 H-Index II
• 276 Paint Fence
• 277 Find the Celebrity
• 278 First Bad Version
• 279 Perfect Squares
• 280 Wiggle Sort
• 281 Zigzag Iterator
• 282 Expression Add Operators
• 283 Move Zeroes
• 284 Peeking Iterator
• 285 Inorder Successor in BST
• 286 Walls and Gates
• 288 Unique Word Abbreviation
• 289 Game of Life
• 290 Word Pattern
• 291 Word Pattern II
• 292 Nim Game
• 293 Flip Game
• 294 Flip Game II
• 295 Find Median from Data Stream
• 297 Serialize and Deserialize Binary Tree
• 298 Binary Tree Longest Consecutive Sequence
• 299 Bulls and Cows
• 301 Remove Invalid Parentheses
• 302 Smallest Rectangle Enclosing Black Pixels
• 303 Range Sum Query - Immutable
• 304 Range Sum Query 2D - Immutable
• 305 Number of Islands II
• 306 Additive Number
• 307 Range Sum Query - Mutable
• 308 Range Sum Query 2D - Mutable
• 309 Best Time to Buy and Sell Stock with Cooldown
• 310 Minimum Height Trees
• 311 Sparse Matrix Multiplication
• 312 Burst Balloons
• 313 Super Ugly Number
• 314 Binary Tree Vertical Order Traversal
• 315 Count of Smaller Numbers After Self
• 316 Remove Duplicate Letters
• 317 Shortest Distance from All Buildings
• 318 Maximum Product of Word Lengths
• 319 Bulb Switcher
• 320 Generalized Abbreviation
• 321 Create Maximum Number
• 322 Coin Change
• 323 Number of Connected Components in an Undirected Graph
• 324 Wiggle Sort II
• 325 Maximum Size Subarray Sum Equals k
• 326 Power of Three
• 327 Count of Range Sum
• 328 Odd Even Linked List
• 329 Longest Increasing Path in a Matrix
• 330 Patching Array
• 331 Verify Preorder Serialization of a Binary Tree
• 332 Reconstruct Itinerary
• 333 Largest BST Subtree
• 334 Increasing Triplet Subsequence
• 336 Palindrome Pairs
• 337 House Robber III
• 338 Counting Bits
• 339 Nested List Weight Sum
• 340 Longest Substring with At Most K Distinct Characters
• 341 Flatten Nested List Iterator
• 342 Power of Four
• 343 Integer Break
• 344 Reverse String
• 345 Reverse Vowels of a String
• 346 Moving Average from Data Stream
• 347 Top K Frequent Elements
• 348 Design Tic-Tac-Toe
• 349 Intersection of Two Arrays
• 350 Intersection of Two Arrays II
• 351 Android Unlock Patterns
• 353 Design Snake Game
• 354 Russian Doll Envelopes
• 355 Design Twitter
• 356 Line Reflection
• 357 Count Numbers with Unique Digits
• 358 Rearrange String k Distance Apart
• 359 Logger Rate Limiter
• 360 Sort Transformed Array
• 361 Bomb Enemy
• 362 Design Hit Counter
• 363 Max Sum of Rectangle No Larger Than K
• 364 Nested List Weight Sum II
• 365 Water and Jug Problem
• 366 Find Leaves of Binary Tree
• 367 Valid Perfect Square
• 368 Largest Divisible Subset
• 369 Plus One Linked List
• 370 Range Addition
• 371 Sum of Two Integers
• 372 Super Pow
• 373 Find K Pairs with Smallest Sums
• 374 Guess Number Higher or Lower
• 375 Guess Number Higher or Lower II
• 377 Combination Sum IV
• 378 Kth Smallest Element in a Sorted Matrix
• 379 Design Phone Directory
• 380 Insert Delete GetRandom O(1)
• 382 Linked List Random Node
• 388 Longest Absolute File Path
• 389 Find the Difference
• 391 Perfect Rectangle
• 393 UTF-8 Validation
• 394 Decode String
• 397 Integer Replacement
• 398 Random Pick Index
• 399 Evaluate Division
• 400 Nth Digit
• 401 Binary Watch
• 402 Remove K Digits
• 404 Sum of Left Leaves
• 406 Queue Reconstruction by Height
• 407 Trapping Rain Water II
• 408 Valid Word Abbreviation
• 409 Longest Palindrome
• 411 Minimum Unique Word Abbreviation
• 415 Add Strings
• 417 Pacific Atlantic Water Flow
• 418 Sentence Screen Fitting
• 421 Maximum XOR of Two Numbers in an Array
• 422 Valid Word Square
• 425 Word Squares
• 444 Sequence Reconstruction
• 447 Number of Boomerangs
• 448 Find All Numbers Disappeared in an Array
• 404 Sum of Left Leaves
• 410 Split Array Largest Sum
• 432 All O`one Data Structure
• 437 Path Sum III
• 450 Delete Node in a BST
• 451 Sort Characters By Frequency
• 459 Repeated Substring Pattern
• 460 LFU Cache
• 461 Hamming Distance
• 463 Island Perimeter
• 465 Optimal Account Balancing
• 469 Convex Polygon
• 471 Encode String with Shortest Length
• 474 Ones and Zeroes
• 475 Heaters
• 480 Sliding Window Median
• 481 Magical String
• 482 License Key Formatting
• 483 Smallest Good Base
• 484 Find Permutation
• 485 Max Consecutive Ones
• 486 Predict the Winner
• 487 Max Consecutive Ones II
• 490 The Maze
• 493 Reverse Pairs
• 494 Target Sum
• 498 Diagonal Traverse
• 501 Find Mode in Binary Search Tree
• 503 Next Greater Element II
• 505 The Maze II
• 506 Relative Ranks
• 514 Freedom Trail
• 515 Find Largest Value in Each Tree Row
• 520 Detect Capital
• 521 Longest Uncommon Subsequence I
• 522 Longest Uncommon Subsequence II
• 523 Continuous Subarray Sum
• 524 Longest Word in Dictionary through Deleting
• 525 Contiguous Array
• 526 Beautiful Arrangement
• 527 Word Abbreviation
• 530 Minimum Absolute Difference in BST
• 531 Lonely Pixel I
• 533 Lonely Pixel II
• 534 Design TinyURL
• 535 Encode and Decode TinyURL
• 541 Reverse String II
• 542 01 Matrix
• 543 Diameter of Binary Tree
• 544 Output Contest Matches
• 545 Boundary of Binary Tree
• 549 Binary Tree Longest Consecutive Sequence II
• 516 Longest Palindromic Subsequence
• 551 Student Attendance Record I
• 552 Student Attendance Record II
• 560 Subarray Sum Equals K
• 562 Longest Line of Consecutive One in Matrix
• 568 Maximum Vacation Days
• 569 Median Employee Salary
• 554 Brick Wall
• 621 Task Scheduler
• 633 Sum of Square Numbers
• 636 Exclusive Time of Functions
• 637 Average of Levels in Binary Tree
• 639 Decode Ways II
• 642 Design Search Autocomplete System
• 647 Palindromic Substrings
• 648 Replace Words
• 653 Two Sum IV - Input is a BST
• 689 Maximum Sum of 3 Non-Overlapping Subarrays
• 670 Maximum Swap
• 671 Second Minimum Node In a Binary Tree
• 680 Valid Palindrome II
• 690 Employee Importance
• 692 Top K Frequent Words
• 698 Partition to K Equal Sum Subsets
• 699 Falling Squares
• 714 Best Time to Buy and Sell Stock with Transaction Fee
• 716 Max Stack
• 744 Find Smallest Letter Greater Than Target
• 730 Count Different Palindromic Subsequences
• 733 Flood Fill
• 735 Asteroid Collision
• Best Time to Buy and Sell S- tock