LeetCode.swift

愚者千虑，必有一得。

As an idiot of algorithms, I make bold to resolve the problems on LeetCode, especially, in Swift. Most of the algorithms were not figured out by myself.

let 😎 = "Easy", 😐 = "Medium", 😨 = "Hard", ㊙️ = "require premium membership"

• 1 😎 Two Sum .swift
• 2 😐 Add Two Numbers .swift
• 3 😐 Longest Substring Without Repeating Characters .swift
• 4 😨 Median of Two Sorted Arrays
• 5 😐 Longest Palindromic Substring .swift
• 6 😐 ZigZag Conversion .swift
• 7 😎 Reverse Integer .swift
• 8 😐 String to Integer (atoi) .swift
• 9 😎 Palindrome Number .swift
• 10 😨 Regular Expression Matching
• 11 😐 Container With Most Water
• 12 😐 Integer to Roman .swift
• 13 😎 Roman to Integer .swift
• 14 😎 Longest Common Prefix .swift
• 15 😐 3Sum
• 16 😐 3Sum Closest
• 17 😐 Letter Combinations of a Phone Number .swift
• 18 😐 4Sum
• 19 😐 Remove Nth Node From End of List .swift
• 20 😎 Valid Parentheses .swift
• 21 😎 Merge Two Sorted Lists .swift
• 22 😐 Generate Parentheses
• 23 😨 Merge k Sorted Lists
• 24 😐 Swap Nodes in Pairs
• 25 😨 Reverse Nodes in k-Group
• 26 😎 Remove Duplicates from Sorted Array .swift
• 27 😎 Remove Element .swift
• 28 😎 Implement strStr() .swift
• 29 😐 Divide Two Integers
• 30 😨 Substring with Concatenation of All Words
• 31 😐 Next Permutation
• 32 😨 Longest Valid Parentheses
• 33 😐 Search in Rotated Sorted Array
• 34 😐 Find First and Last Position of Element in Sorted Array
• 35 😎 Search Insert Position .swift
• 36 😐 Valid Sudoku
• 37 😨 Sudoku Solver
• 38 😎 Count and Say .swift
• 39 😐 Combination Sum
• 40 😐 Combination Sum II
• 41 😨 First Missing Positive
• 42 😨 Trapping Rain Water
• 43 😐 Multiply Strings
• 44 😨 Wildcard Matching
• 45 😨 Jump Game II
• 46 😐 Permutations
• 47 😐 Permutations II
• 48 😐 Rotate Image
• 49 😐 Group Anagrams .swift
• 50 😐 Pow(x, n)
• 51 😨 N-Queens
• 52 😨 N-Queens II
• 53 😎 Maximum Subarray
• 54 😐 Spiral Matrix
• 55 😐 Jump Game
• 56 😐 Merge Intervals
• 57 😨 Insert Interval
• 58 😎 Length of Last Word .swift
• 59 😐 Spiral Matrix II
• 60 😐 Permutation Sequence
• 61 😐 Rotate List
• 62 😐 Unique Paths
• 63 😐 Unique Paths II
• 64 😐 Minimum Path Sum
• 65 😨 Valid Number .swift
• 66 😎 Plus One .swift
• 67 😎 Add Binary .swift
• 68 😨 Text Justification
• 69 😎 Sqrt(x)
• 70 😎 Climbing Stairs
• 71 😐 Simplify Path
• 72 😨 Edit Distance
• 73 😐 Set Matrix Zeroes
• 74 😐 Search a 2D Matrix
• 75 😐 Sort Colors
• 76 😨 Minimum Window Substring
• 77 😐 Combinations
• 78 😐 Subsets
• 79 😐 Word Search
• 80 😐 Remove Duplicates from Sorted Array II
• 81 😐 Search in Rotated Sorted Array II
• 82 😐 Remove Duplicates from Sorted List II .swift
• 83 😎 Remove Duplicates from Sorted List .swift
• 84 😨 Largest Rectangle in Histogram
• 85 😨 Maximal Rectangle
• 86 😐 Partition List
• 87 😨 Scramble String
• 88 😎 Merge Sorted Array .swift
• 89 😐 Gray Code
• 90 😐 Subsets II
• 91 😐 Decode Ways
• 92 😐 Reverse Linked List II
• 93 😐 Restore IP Addresses
• 94 😐 Binary Tree Inorder Traversal
• 95 😐 Unique Binary Search Trees II
• 96 😐 Unique Binary Search Trees
• 97 😨 Interleaving String
• 98 😐 Validate Binary Search Tree
• 99 😨 Recover Binary Search Tree
• 100 😎 Same Tree .swift
• 101 😎 Symmetric Tree .swift
• 102 😐 Binary Tree Level Order Traversal
• 103 😐 Binary Tree Zigzag Level Order Traversal
• 104 😎 Maximum Depth of Binary Tree .swift
• 105 😐 Construct Binary Tree from Preorder and Inorder Traversal
• 106 😐 Construct Binary Tree from Inorder and Postorder Traversal
• 107 😎 Binary Tree Level Order Traversal II
• 108 😎 Convert Sorted Array to Binary Search Tree
• 109 😐 Convert Sorted List to Binary Search Tree
• 110 😎 Balanced Binary Tree .swift
• 111 😎 Minimum Depth of Binary Tree .swift
• 112 😎 Path Sum
• 113 😐 Path Sum II
• 114 😐 Flatten Binary Tree to Linked List .swift
• 115 😨 Distinct Subsequences
• 116 😐 Populating Next Right Pointers in Each Node
• 117 😐 Populating Next Right Pointers in Each Node II
• 118 😎 Pascal's Triangle
• 119 😎 Pascal's Triangle II
• 120 😐 Triangle
• 121 😎 Best Time to Buy and Sell Stock
• 122 😎 Best Time to Buy and Sell Stock II
• 123 😨 Best Time to Buy and Sell Stock III
• 124 😨 Binary Tree Maximum Path Sum
• 125 😎 Valid Palindrome
• 126 😨 Word Ladder II
• 127 😐 Word Ladder
• 128 😨 Longest Consecutive Sequence
• 129 😐 Sum Root to Leaf Numbers
• 130 😐 Surrounded Regions
• 131 😐 Palindrome Partitioning
• 132 😨 Palindrome Partitioning II
• 133 😐 Clone Graph
• 134 😐 Gas Station
• 135 😨 Candy
• 136 😎 Single Number .swift
• 137 😐 Single Number II
• 138 😐 Copy List with Random Pointer
• 139 😐 Word Break
• 140 😨 Word Break II
• 141 😎 Linked List Cycle
• 142 😐 Linked List Cycle II
• 143 😐 Reorder List
• 144 😐 Binary Tree Preorder Traversal
• 145 😨 Binary Tree Postorder Traversal
• 146 😨 LRU Cache
• 147 😐 Insertion Sort List
• 148 😐 Sort List
• 149 😨 Max Points on a Line
• 150 😐 Evaluate Reverse Polish Notation
• 151 😐 Reverse Words in a String
• 152 😐 Maximum Product Subarray
• 153 😐 Find Minimum in Rotated Sorted Array
• 154 😨 Find Minimum in Rotated Sorted Array II
• 155 😎 Min Stack .swift
• 156 😐 Binary Tree Upside Down ㊙️
• 157 😎 Read N Characters Given Read4 ㊙️
• 158 😨 Read N Characters Given Read4 II - Call multiple times ㊙️
• 159 😨 Longest Substring with At Most Two Distinct Characters ㊙️
• 160 😎 Intersection of Two Linked Lists
• 161 😐 One Edit Distance ㊙️
• 162 😐 Find Peak Element
• 163 😐 Missing Ranges ㊙️
• 164 😨 Maximum Gap
• 165 😐 Compare Version Numbers .swift
• 166 😐 Fraction to Recurring Decimal
• 167 😎 Two Sum II - Input array is sorted
• 168 😎 Excel Sheet Column Title
• 169 😎 Majority Element
• 170 😎 Two Sum III - Data structure design ㊙️
• 171 😎 Excel Sheet Column Number
• 172 😎 Factorial Trailing Zeroes
• 173 😐 Binary Search Tree Iterator
• 174 😨 Dungeon Game
• 179 😐 Largest Number
• 186 😐 Reverse Words in a String II ㊙️
• 187 😐 Repeated DNA Sequences
• 188 😨 Best Time to Buy and Sell Stock IV
• 189 😎 Rotate Array .swift
• 190 😎 Reverse Bits
• 191 😎 Number of 1 Bits
• 198 😎 House Robber
• 199 😐 Binary Tree Right Side View
• 200 😐 Number of Islands
• 201 😐 Bitwise AND of Numbers Range
• 202 😎 Happy Number
• 203 😎 Remove Linked List Elements
• 204 😎 Count Primes
• 205 😎 Isomorphic Strings
• 206 😎 Reverse Linked List
• 207 😐 Course Schedule
• 208 😐 Implement Trie (Prefix Tree)
• 209 😐 Minimum Size Subarray Sum
• 210 😐 Course Schedule II
• 211 😐 Add and Search Word - Data structure design
• 212 😨 Word Search II
• 213 😐 House Robber II
• 214 😨 Shortest Palindrome
• 215 😐 Kth Largest Element in an Array
• 216 😐 Combination Sum III
• 217 😎 Contains Duplicate
• 218 😨 The Skyline Problem
• 219 😎 Contains Duplicate II
• 220 😐 Contains Duplicate III
• 221 😐 Maximal Square
• 222 😐 Count Complete Tree Nodes
• 223 😐 Rectangle Area
• 224 😨 Basic Calculator
• 225 😎 Implement Stack using Queues
• 226 😎 Invert Binary Tree .swift
• 227 😐 Basic Calculator II
• 228 😐 Summary Ranges
• 229 😐 Majority Element II
• 230 😐 Kth Smallest Element in a BST
• 231 😎 Power of Two
• 232 😎 Implement Queue using Stacks
• 233 😨 Number of Digit One
• 234 😎 Palindrome Linked List
• 235 😎 Lowest Common Ancestor of a Binary Search Tree
• 236 😐 Lowest Common Ancestor of a Binary Tree
• 237 😎 Delete Node in a Linked List
• 238 😐 Product of Array Except Self
• 239 😨 Sliding Window Maximum
• 240 😐 Search a 2D Matrix II
• 241 😐 Different Ways to Add Parentheses
• 242 😎 Valid Anagram .swift
• 243 😎 Shortest Word Distance ㊙️
• 244 😐 Shortest Word Distance II ㊙️
• 245 😐 Shortest Word Distance III ㊙️
• 246 😎 Strobogrammatic Number ㊙️
• 247 😐 Strobogrammatic Number II ㊙️
• 248 😨 Strobogrammatic Number III ㊙️
• 249 😐 Group Shifted Strings ㊙️
• 250 😐 Count Univalue Subtrees ㊙️
• 251 😐 Flatten 2D Vector ㊙️
• 252 😎 Meeting Rooms ㊙️
• 253 😐 Meeting Rooms II ㊙️
• 254 😐 Factor Combinations ㊙️
• 255 😐 Verify Preorder Sequence in Binary Search Tree ㊙️
• 256 😎 Paint House ㊙️
• 257 😎 Binary Tree Paths
• 258 😎 Add Digits .swift
• 259 😐 3Sum Smaller ㊙️
• 260 😐 Single Number III
• 261 😐 Graph Valid Tree ㊙️
• 263 😎 Ugly Number .swift
• 264 😐 Ugly Number II
• 265 😨 Paint House II ㊙️
• 266 😎 Palindrome Permutation ㊙️
• 267 😐 Palindrome Permutation II ㊙️
• 268 😎 Missing Number .swift
• 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 .swift
• 284 😐 Peeking Iterator
• 285 😐 Inorder Successor in BST ㊙️
• 286 😐 Walls and Gates ㊙️
• 287 😐 Find the Duplicate Number
• 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
• 296 😨 Best Meeting Point ㊙️
• 297 😨 Serialize and Deserialize Binary Tree
• 298 😐 Binary Tree Longest Consecutive Sequence ㊙️
• 299 😐 Bulls and Cows
• 300 😐 Longest Increasing Subsequence
• 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 .swift
• 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
• 335 😨 Self Crossing
• 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 ㊙️
• 352 😨 Data Stream as Disjoint Intervals
• 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
• 376 😐 Wiggle Subsequence
• 377 😐 Combination Sum IV
• 378 😐 Kth Smallest Element in a Sorted Matrix
• 379 😐 Design Phone Directory ㊙️
• 380 😐 Insert Delete GetRandom O(1)
• 381 😨 Insert Delete GetRandom O(1) - Duplicates allowed
• 382 😐 Linked List Random Node
• 383 😎 Ransom Note
• 384 😐 Shuffle an Array
• 385 😐 Mini Parser
• 386 😐 Lexicographical Numbers
• 387 😎 First Unique Character in a String
• 388 😐 Longest Absolute File Path
• 389 😎 Find the Difference
• 390 😐 Elimination Game
• 391 😨 Perfect Rectangle
• 392 😐 Is Subsequence
• 393 😐 UTF-8 Validation
• 394 😐 Decode String
• 395 😐 Longest Substring with At Least K Repeating Characters
• 396 😐 Rotate Function
• 397 😐 Integer Replacement
• 398 😐 Random Pick Index
• 399 😐 Evaluate Division
• 400 😎 Nth Digit
• 401 😎 Binary Watch
• 402 😐 Remove K Digits
• 403 😨 Frog Jump
• 404 😎 Sum of Left Leaves
• 405 😎 Convert a Number to Hexadecimal
• 406 😐 Queue Reconstruction by Height
• 407 😨 Trapping Rain Water II
• 408 😎 Valid Word Abbreviation ㊙️
• 409 😎 Longest Palindrome
• 410 😨 Split Array Largest Sum
• 411 😨 Minimum Unique Word Abbreviation ㊙️
• 412 😎 Fizz Buzz
• 413 😐 Arithmetic Slices
• 414 😎 Third Maximum Number
• 415 😎 Add Strings
• 416 😐 Partition Equal Subset Sum
• 417 😐 Pacific Atlantic Water Flow
• 418 😐 Sentence Screen Fitting ㊙️
• 419 😐 Battleships in a Board
• 420 😨 Strong Password Checker
• 421 😐 Maximum XOR of Two Numbers in an Array
• 422 😎 Valid Word Square ㊙️
• 423 😐 Reconstruct Original Digits from English
• 424 😐 Longest Repeating Character Replacement
• 425 😨 Word Squares ㊙️
• 432 😨 All O`one Data Structure
• 433 😐 Minimum Genetic Mutation
• 434 😎 Number of Segments in a String
• 435 😐 Non-overlapping Intervals
• 436 😐 Find Right Interval
• 437 😎 Path Sum III
• 438 😎 Find All Anagrams in a String
• 439 😐 Ternary Expression Parser ㊙️
• 440 😨 K-th Smallest in Lexicographical Order
• 441 😎 Arranging Coins
• 442 😐 Find All Duplicates in an Array
• 443 😎 String Compression
• 444 😐 Sequence Reconstruction ㊙️
• 445 😐 Add Two Numbers II
• 446 😨 Arithmetic Slices II - Subsequence
• 447 😎 Number of Boomerangs
• 448 😎 Find All Numbers Disappeared in an Array
• 449 😐 Serialize and Deserialize BST
• 450 😐 Delete Node in a BST
• 451 😐 Sort Characters By Frequency
• 452 😐 Minimum Number of Arrows to Burst Balloons
• 453 😎 Minimum Moves to Equal Array Elements
• 454 😐 4Sum II
• 455 😎 Assign Cookies
• 456 😐 132 Pattern
• 457 😐 Circular Array Loop
• 458 😎 Poor Pigs
• 459 😎 Repeated Substring Pattern
• 460 😨 LFU Cache
• 461 😎 Hamming Distance .swift
• 462 😐 Minimum Moves to Equal Array Elements II
• 463 😎 Island Perimeter
• 464 😐 Can I Win
• 465 😨 Optimal Account Balancing ㊙️
• 466 😨 Count The Repetitions
• 467 😐 Unique Substrings in Wraparound String
• 468 😐 Validate IP Address
• 469 😐 Convex Polygon ㊙️
• 471 😨 Encode String with Shortest Length ㊙️
• 472 😨 Concatenated Words
• 473 😐 Matchsticks to Square
• 474 😐 Ones and Zeroes
• 475 😎 Heaters
• 476 😎 Number Complement .swift
• 477 😐 Total Hamming Distance
• 479 😎 Largest Palindrome Product
• 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 ㊙️
• 488 😨 Zuma Game
• 490 😐 The Maze ㊙️
• 491 😐 Increasing Subsequences
• 492 😎 Construct the Rectangle
• 493 😨 Reverse Pairs
• 494 😐 Target Sum
• 495 😐 Teemo Attacking
• 496 😎 Next Greater Element I
• 498 😐 Diagonal Traverse
• 499 😨 The Maze III ㊙️
• 500 😎 Keyboard Row
• 501 😎 Find Mode in Binary Search Tree
• 502 😨 IPO
• 503 😐 Next Greater Element II
• 504 😎 Base 7 .swift
• 505 😐 The Maze II ㊙️
• 506 😎 Relative Ranks
• 507 😎 Perfect Number
• 508 😐 Most Frequent Subtree Sum
• 513 😐 Find Bottom Left Tree Value
• 514 😨 Freedom Trail
• 515 😐 Find Largest Value in Each Tree Row
• 516 😐 Longest Palindromic Subsequence
• 517 😨 Super Washing Machines
• 518 😐 Coin Change 2
• 520 😎 Detect Capital .swift
• 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 ㊙️
• 529 😐 Minesweeper
• 530 😎 Minimum Absolute Difference in BST
• 531 😐 Lonely Pixel I ㊙️
• 532 😎 K-diff Pairs in an Array
• 533 😐 Lonely Pixel II ㊙️
• 535 😐 Encode and Decode TinyURL
• 536 😐 Construct Binary Tree from String ㊙️
• 537 😐 Complex Number Multiplication
• 538 😎 Convert BST to Greater Tree
• 539 😐 Minimum Time Difference
• 540 😐 Single Element in a Sorted Array
• 541 😎 Reverse String II
• 542 😐 01 Matrix
• 543 😎 Diameter of Binary Tree
• 544 😐 Output Contest Matches ㊙️
• 545 😐 Boundary of Binary Tree ㊙️
• 546 😨 Remove Boxes
• 547 😐 Friend Circles
• 548 😐 Split Array with Equal Sum ㊙️
• 549 😐 Binary Tree Longest Consecutive Sequence II ㊙️
• 551 😎 Student Attendance Record I
• 552 😨 Student Attendance Record II
• 553 😐 Optimal Division
• 554 😐 Brick Wall
• 555 😐 Split Concatenated Strings ㊙️
• 556 😐 Next Greater Element III
• 557 😎 Reverse Words in a String III
• 560 😐 Subarray Sum Equals K
• 561 😎 Array Partition I
• 562 😐 Longest Line of Consecutive One in Matrix ㊙️
• 563 😎 Binary Tree Tilt
• 564 😨 Find the Closest Palindrome
• 565 😐 Array Nesting
• 566 😎 Reshape the Matrix
• 567 😐 Permutation in String
• 568 😨 Maximum Vacation Days ㊙️
• 572 😎 Subtree of Another Tree
• 573 😐 Squirrel Simulation ㊙️
• 575 😎 Distribute Candies
• 576 😐 Out of Boundary Paths
• 581 😎 Shortest Unsorted Continuous Subarray
• 582 😐 Kill Process ㊙️
• 583 😐 Delete Operation for Two Strings
• 587 😨 Erect the Fence
• 588 😨 Design In-Memory File System ㊙️
• 591 😨 Tag Validator
• 592 😐 Fraction Addition and Subtraction
• 593 😐 Valid Square
• 594 😎 Longest Harmonious Subsequence
• 598 😎 Range Addition II
• 599 😎 Minimum Index Sum of Two Lists
• 600 😨 Non-negative Integers without Consecutive Ones
• 604 😎 Design Compressed String Iterator ㊙️
• 605 😎 Can Place Flowers
• 606 😎 Construct String from Binary Tree
• 609 😐 Find Duplicate File in System
• 611 😐 Valid Triangle Number
• 616 😐 Add Bold Tag in String ㊙️
• 617 😎 Merge Two Binary Trees
• 621 😐 Task Scheduler
• 623 😐 Add One Row to Tree
• 624 😎 Maximum Distance in Arrays ㊙️
• 625 😐 Minimum Factorization ㊙️
• 628 😎 Maximum Product of Three Numbers
• 629 😨 K Inverse Pairs Array
• 630 😨 Course Schedule III
• 631 😨 Design Excel Sum Formula ㊙️
• 632 😨 Smallest Range
• 633 😎 Sum of Square Numbers
• 634 😐 Find the Derangement of An Array ㊙️
• 635 😐 Design Log Storage System ㊙️
• 636 😐 Exclusive Time of Functions
• 637 😎 Average of Levels in Binary Tree
• 638 😐 Shopping Offers
• 639 😨 Decode Ways II
• 640 😐 Solve the Equation
• 642 😨 Design Search Autocomplete System ㊙️
• 643 😎 Maximum Average Subarray I
• 644 😨 Maximum Average Subarray II ㊙️
• 645 😎 Set Mismatch
• 646 😐 Maximum Length of Pair Chain
• 647 😐 Palindromic Substrings
• 648 😐 Replace Words
• 649 😐 Dota2 Senate
• 650 😐 2 Keys Keyboard
• 651 😐 4 Keys Keyboard ㊙️
• 652 😐 Find Duplicate Subtrees
• 653 😎 Two Sum IV - Input is a BST
• 654 😐 Maximum Binary Tree
• 655 😐 Print Binary Tree
• 656 😨 Coin Path ㊙️
• 657 😎 Judge Route Circle
• 658 😐 Find K Closest Elements
• 659 😐 Split Array into Consecutive Subsequences
• 660 😨 Remove 9 ㊙️
• 661 😎 Image Smoother
• 662 😐 Maximum Width of Binary Tree
• 663 😐 Equal Tree Partition ㊙️
• 664 😨 Strange Printer
• 665 😎 Non-decreasing Array
• 666 😐 Path Sum IV ㊙️
• 667 😐 Beautiful Arrangement II
• 668 😨 Kth Smallest Number in Multiplication Table
• 669 😎 Trim a Binary Search Tree
• 670 😐 Maximum Swap
• 671 😎 Second Minimum Node In a Binary Tree
• 672 😐 Bulb Switcher II
• 673 😐 Number of Longest Increasing Subsequence
• 674 😎 Longest Continuous Increasing Subsequence
• 675 😨 Cut Off Trees for Golf Event
• 676 😐 Implement Magic Dictionary
• 677 😐 Map Sum Pairs
• 678 😐 Valid Parenthesis String
• 679 😨 24 Game
• 680 😎 Valid Palindrome II
• 681 😐 Next Closest Time ㊙️
• 682 😎 Baseball Game
• 683 😨 K Empty Slots ㊙️
• 684 😐 Redundant Connection
• 685 😨 Redundant Connection II
• 686 😎 Repeated String Match
• 687 😎 Longest Univalue Path
• 688 😐 Knight Probability in Chessboard
• 689 😨 Maximum Sum of 3 Non-Overlapping Subarrays
• 690 😎 Employee Importance
• 691 😨 Stickers to Spell Word
• 692 😐 Top K Frequent Words
• 693 😎 Binary Number with Alternating Bits
• 694 😐 Number of Distinct Islands ㊙️
• 695 😎 Max Area of Island
• 696 😎 Count Binary Substrings
• 697 😎 Degree of an Array
• 698 😐 Partition to K Equal Sum Subsets
• 699 😨 Falling Squares
• 711 😨 Number of Distinct Islands II ㊙️
• 712 😐 Minimum ASCII Delete Sum for Two Strings
• 713 😐 Subarray Product Less Than K
• 714 😐 Best Time to Buy and Sell Stock with Transaction Fee
• 715 😨 Range Module
• 716 😨 Max Stack ㊙️
• 717 😎 1-bit and 2-bit Characters
• 718 😐 Maximum Length of Repeated Subarray
• 719 😨 Find K-th Smallest Pair Distance
• 720 😎 Longest Word in Dictionary
• 721 😐 Accounts Merge
• 722 😐 Remove Comments
• 723 😐 Candy Crush ㊙️
• 724 😎 Find Pivot Index
• 725 😐 Split Linked List in Parts
• 726 😨 Number of Atoms
• 727 😨 Minimum Window Subsequence ㊙️
• 728 😎 Self Dividing Numbers
• 729 😐 My Calendar I
• 730 😨 Count Different Palindromic Subsequences
• 731 😐 My Calendar II
• 732 😨 My Calendar III
• 733 😎 Flood Fill
• 734 😎 Sentence Similarity ㊙️
• 735 😐 Asteroid Collision
• 736 😨 Parse Lisp Expression
• 737 😐 Sentence Similarity II ㊙️
• 738 😐 Monotone Increasing Digits
• 739 😐 Daily Temperatures
• 740 😐 Delete and Earn
• 741 😨 Cherry Pickup
• 709 😎 To Lower Case
• 742 😐 Closest Leaf in a Binary Tree ㊙️
• 743 😐 Network Delay Time
• 744 😎 Find Smallest Letter Greater Than Target
• 745 😨 Prefix and Suffix Search
• 746 😎 Min Cost Climbing Stairs
• 747 😎 Largest Number At Least Twice of Others
• 748 😐 Shortest Completing Word
• 749 😨 Contain Virus
• 750 😐 Number Of Corner Rectangles ㊙️
• 751 😎 IP to CIDR ㊙️
• 752 😐 Open the Lock
• 753 😨 Cracking the Safe
• 754 😐 Reach a Number
• 755 😐 Pour Water ㊙️
• 756 😐 Pyramid Transition Matrix
• 426 😐 Convert Binary Search Tree to Sorted Doubly Linked List ㊙️
• 757 😨 Set Intersection Size At Least Two
• 758 😎 Bold Words in String ㊙️
• 759 😨 Employee Free Time ㊙️
• 760 😎 Find Anagram Mappings ㊙️
• 761 😨 Special Binary String
• 429 😎 N-ary Tree Level Order Traversal
• 428 😨 Serialize and Deserialize N-ary Tree ㊙️
• 430 😐 Flatten a Multilevel Doubly Linked List
• 762 😎 Prime Number of Set Bits in Binary Representation
• 763 😐 Partition Labels
• 764 😐 Largest Plus Sign
• 765 😨 Couples Holding Hands
• 431 😨 Encode N-ary Tree to Binary Tree ㊙️
• 427 😎 Construct Quad Tree
• 558 😎 Quad Tree Intersection
• 559 😎 Maximum Depth of N-ary Tree
• 589 😎 N-ary Tree Preorder Traversal
• 590 😎 N-ary Tree Postorder Traversal
• 766 😎 Toeplitz Matrix
• 767 😐 Reorganize String
• 768 😨 Max Chunks To Make Sorted II
• 769 😐 Max Chunks To Make Sorted
• 770 😨 Basic Calculator IV
• 771 😎 Jewels and Stones
• 700 😎 Search in a Binary Search Tree
• 701 😐 Insert into a Binary Search Tree
• 772 😨 Basic Calculator III ㊙️
• 702 😐 Search in a Sorted Array of Unknown Size ㊙️
• 773 😨 Sliding Puzzle
• 774 😨 Minimize Max Distance to Gas Station ㊙️
• 703 😎 Kth Largest Element in a Stream
• 775 😐 Global and Local Inversions
• 776 😐 Split BST ㊙️
• 704 😎 Binary Search
• 777 😐 Swap Adjacent in LR String
• 778 😨 Swim in Rising Water
• 779 😐 K-th Symbol in Grammar
• 780 😨 Reaching Points
• 781 😐 Rabbits in Forest
• 782 😨 Transform to Chessboard
• 783 😎 Minimum Distance Between BST Nodes
• 784 😎 Letter Case Permutation
• 785 😐 Is Graph Bipartite?
• 786 😨 K-th Smallest Prime Fraction
• 787 😐 Cheapest Flights Within K Stops
• 788 😎 Rotated Digits .swift
• 789 😐 Escape The Ghosts
• 790 😐 Domino and Tromino Tiling
• 791 😐 Custom Sort String
• 792 😐 Number of Matching Subsequences
• 793 😨 Preimage Size of Factorial Zeroes Function
• 794 😐 Valid Tic-Tac-Toe State
• 795 😐 Number of Subarrays with Bounded Maximum
• 796 😎 Rotate String .swift
• 797 😐 All Paths From Source to Target
• 798 😨 Smallest Rotation with Highest Score
• 799 😐 Champagne Tower
• 705 😎 Design HashSet
• 706 😎 Design HashMap
• 800 😎 Similar RGB Color ㊙️
• 801 😐 Minimum Swaps To Make Sequences Increasing
• 802 😐 Find Eventual Safe States
• 803 😨 Bricks Falling When Hit
• 804 😎 Unique Morse Code Words .swift
• 805 😨 Split Array With Same Average
• 806 😎 Number of Lines To Write String .swift
• 807 😐 Max Increase to Keep City Skyline
• 808 😐 Soup Servings
• 809 😐 Expressive Words
• 810 😨 Chalkboard XOR Game
• 811 😎 Subdomain Visit Count .swift
• 812 😎 Largest Triangle Area
• 813 😐 Largest Sum of Averages
• 814 😐 Binary Tree Pruning
• 815 😨 Bus Routes
• 816 😐 Ambiguous Coordinates
• 817 😐 Linked List Components
• 818 😨 Race Car
• 819 😎 Most Common Word .swift
• 707 😎 Design Linked List
• 820 😐 Short Encoding of Words
• 821 😎 Shortest Distance to a Character
• 822 😐 Card Flipping Game
• 823 😐 Binary Trees With Factors
• 708 😐 Insert into a Cyclic Sorted List ㊙️
• 824 😎 Goat Latin .swift
• 825 😐 Friends Of Appropriate Ages
• 826 😐 Most Profit Assigning Work
• 827 😨 Making A Large Island
• 828 😨 Unique Letter String
• 829 😐 Consecutive Numbers Sum
• 830 😎 Positions of Large Groups .swift
• 831 😐 Masking Personal Information
• 641 😐 Design Circular Deque
• 622 😐 Design Circular Queue
• 832 😎 Flipping an Image .swift
• 833 😐 Find And Replace in String
• 834 😨 Sum of Distances in Tree
• 835 😐 Image Overlap
• 489 😨 Robot Room Cleaner ㊙️
• 836 😎 Rectangle Overlap .swift
• 837 😐 New 21 Game
• 838 😐 Push Dominoes
• 839 😨 Similar String Groups
• 840 😎 Magic Squares In Grid .swift
• 841 😐 Keys and Rooms
• 842 😐 Split Array into Fibonacci Sequence
• 843 😨 Guess the Word
• 844 😎 Backspace String Compare .swift
• 845 😐 Longest Mountain in Array
• 846 😐 Hand of Straights
• 847 😨 Shortest Path Visiting All Nodes
• 848 😐 Shifting Letters
• 849 😎 Maximize Distance to Closest Person
• 850 😨 Rectangle Area II
• 851 😐 Loud and Rich
• 852 😎 Peak Index in a Mountain Array .swift
• 853 😐 Car Fleet
• 854 😨 K-Similar Strings
• 855 😐 Exam Room
• 856 😐 Score of Parentheses
• 857 😨 Minimum Cost to Hire K Workers
• 858 😐 Mirror Reflection
• 859 😎 Buddy Strings .swift
• 860 😎 Lemonade Change .swift
• 861 😐 Score After Flipping Matrix
• 862 😨 Shortest Subarray with Sum at Least K
• 863 😐 All Nodes Distance K in Binary Tree
• 710 😨 Random Pick with Blacklist
• 864 😨 Shortest Path to Get All Keys
• 865 😐 Smallest Subtree with all the Deepest Nodes
• 866 😐 Prime Palindrome
• 867 😎 Transpose Matrix
• 868 😎 Binary Gap .swift
• 869 😐 Reordered Power of 2
• 870 😐 Advantage Shuffle
• 871 😨 Minimum Number of Refueling Stops
• 470 😐 Implement Rand10() Using Rand7()

Unit tests

This is a test-driven project. You may press ⌘ + u in Xcode to invoke the tests. Or just rake in CLI.

License