LeetCode LeetCode Algorithm You can use ⌘ + F to search the answer you want On non-macOS computers, please substitute CTRL for ⌘ . # Title Solution Difficulty 344 Reverse String Objective-C、Swift Easy 541 Reverse String II Swift Easy 345 Reverse Vowels of a String Swift Easy 258 Add Digits Objective-C、Swift Easy 389 Find the Difference Objective-C、Swift Easy 226 Invert Binary Tree Objective-C、Swift Easy 283 Move Zeroes Objective-C、Swift Easy 404 Sum of Left Leaves Objective-C、Swift Easy 409 Longest Palindrome Objective-C、Swift Easy 383 Ransom Note Objective-C、Swift Easy 237 Delete Node in a Linked List Objective-C Easy 349 Intersection of Two Arrays Objective-C、Swift Easy 100 Same Tree Objective-C、Swift Easy 171 Excel Sheet Column Number Objective-C、Swift Easy 242 Valid Anagram Objective-C、Swift Easy 169 Majority Element Objective-C、Swift Easy 387 First Unique Character in a String Objective-C、Swift Easy 217 Contains Duplicate Objective-C、Swift Easy 219 Contains Duplicate II Swift Easy 350 Intersection of Two Arrays II Objective-C、Swift Easy 13 Roman to Integer Objective-C、Swift Easy 412 Fizz Buzz Objective-C、Swift Easy 206 Reverse Linked List Objective-C、Swift Easy 415 Add Strings Objective-C、Swift Easy 405 Convert a Number to Hexadecimal Objective-C、Swift Easy 231 Power of Two Objective-C、Swift Easy 326 Power of Three Objective-C、Swift Easy 202 Happy Number Objective-C、Swift Easy 121 Best Time to Buy and Sell Stock Objective-C、Swift Easy 83 Remove Duplicates from Sorted List Objective-C、Swift Easy 70 Climbing Stairs Objective-C、Swift Easy 104 Maximum Depth of Binary Tree Objective-C、Swift Easy 461 Hamming Distance Objective-C、Swift Easy 476 Number Complement Objective-C、Swift Easy 496 Next Greater Element I Objective-C、Swift Easy 520 Detect Capital Objective-C、Swift Easy 371 Sum of Two Integers Objective-C、Swift Easy 657 Judge Route Circle Swift Easy 617 Merge Two Binary Trees Swift Easy 561 Array Partition I Swift Easy 500 Keyboard Row Swift Easy 557 Reverse Words in a String III Swift Easy 575 Distribute Candies Swift Easy 566 Reshape the Matrix Swift Easy 463 Island Perimeter Swift Easy 637 Average of Levels in Binary Tree Swift Easy 521 Longest Uncommon Subsequence I Swift Easy 485 Max Consecutive Ones Swift Easy 448 Find All Numbers Disappeared in an Array Swift Easy 653 Two Sum IV - Input is a BST Swift Easy 606 Construct String from Binary Tree Swift Easy 538 Convert BST to Greater Tree Swift Easy 492 Construct the Rectangle Swift Easy 598 Range Addition II Swift Easy 453 Minimum Moves to Equal Array Elements Swift Easy 530 Minimum Absolute Difference in BST Swift Easy 455 Assign Cookies Swift Easy 122 Best Time to Buy and Sell Stock II Swift Easy 167 Two Sum II - Input array is sorted Swift Easy 563 Binary Tree Tilt Swift Easy 599 Minimum Index Sum of Two Lists Swift Easy 661 Image Smoother Swift Easy 506 Relative Ranks Swift Easy 628 Maximum Product of Three Numbers Swift Easy 447 Number of Boomerangs Swift Easy 401 Binary Watch Swift Easy 504 Base 7 Swift Easy 268 Missing Number Swift Easy 674 Longest Continuous Increasing Subsequence Swift Easy 543 Diameter of Binary Tree Swift Easy 551 Student Attendance Record I Swift Easy 671 Second Minimum Node In a Binary Tree Swift Easy 108 Convert Sorted Array to Binary Search Tree Swift Easy 594 Longest Harmonious Subsequence Swift Easy 572 Subtree of Another Tree Swift Easy 107 Binary Tree Level Order Traversal II Swift Easy 645 Set Mismatch Swift Easy 437 Path Sum III Swift Easy 53 Maximum Subarray Swift Easy 35 Search Insert Position Swift Easy 27 Remove Element Swift Easy 263 Ugly Number Swift Easy 21 Merge Two Sorted Lists Swift Easy 198 House Robber Swift Easy 257 Binary Tree Paths Swift Easy 1 Two Sum Swift Easy 118 Pascal's Triangle Swift Easy 119 Pascal's Triangle II Swift Easy 342 Power of Four Swift Easy 101 Symmetric Tree Swift Easy 367 Valid Perfect Square Swift Easy 66 Plus One Swift Easy 459 Repeated Substring Pattern Swift Easy 9 Palindrome Number Swift Easy 110 Balanced Binary Tree Swift Easy 26 Remove Duplicates from Sorted Array Swift Easy 643 Maximum Average Subarray I Swift Easy 441 Arranging Coins Swift Easy 501 Find Mode in Binary Search Tree Swift Easy 434 Number of Segments in a String Swift Easy 172 Factorial Trailing Zeroes Swift Easy 38 Count and Say Swift Easy 112 Path Sum Swift Easy 507 Perfect Number Swift Easy 205 Isomorphic Strings Swift Easy 438 Find All Anagrams in a String Swift Easy 20 Vaild Parentheses Swift Easy 290 Word Pattern Swift Easy 720 Longest Word in Dictionary Swift Easy 724 Find Pivot Index Swift Easy 680 Valid Palindrome II Swift Easy 58 Length of Last Word Swift Easy 88 Merge Sorted Array Swift Easy 203 Remove Linked List Elements Swift Easy 633 Sum of Square Numbers Swift Easy 686 Repeated String Match Swift Easy 111 Minimum Depth of Binary Tree Swift Easy 234 Palindrome Linked List Swift Easy 687 Longest Univalue Path Swift Easy 7 Reverse Integer Swift Easy 14 Longest Common Prefix Swift Easy 414 Third Maximum Number Swift Easy 605 Can Place Flowers Swift Easy 400 Nth Digit Swift Easy 443 String Compression Swift Easy 475 Heaters Swift Easy 69 Sqrt(x) Swift Easy 204 Count Primes Swift Easy 28 Implement strStr() Swift Easy 168 Excel Sheet Column Title Swift Easy 581 Shortest Unsorted Continuous Subarray Swift Easy 125 Valid Palindrome Swift Easy 788 Rotated Digits Swift Easy 189 Rotate Array Swift Easy 665 Non-decreasing Array Swift Easy 669 Trim a Binary Search Tree Swift Easy 532 K-diff Pairs in an Array Swift Easy 693 Binary Number with Alternating Bits Swift Easy 695 Max Area of Island Swift Easy 696 Count Binary Substrings Swift Easy 697 Degree of an Array Swift Easy 717 1-bit and 2-bit Characters Swift Easy 733 Flood Fill Swift Easy 748 Largest Number At Least Twice of Others Swift Easy 682 Baseball Game Swift Easy 479 Largest Palindrome Product Swift Easy 744 Find Smallest Letter Greater Than Target Swift Easy 747 Min Cost Climbing Stairs Swift Easy 760 Find Anagram Mappings Swift Easy 762 Prime Number of Set Bits in Binary Representation Swift Easy 482 License Key Formatting Swift Easy 771 Jewels and Stones Swift Easy 766 Toeplitz Matrix Swift Easy 442 Find All Duplicates in an Array Swift Medium 540 Single Element in a Sorted Array Swift Medium 654 Maximum Binary Tree Swift Medium 515 Find Largest Value in Each Tree Row Swift Medium 260 Single Number III Swift Medium 513 Find Bottom Left Tree Value Swift Medium 728 Self Dividing Numbers Swift Medium 537 Complex Number Multiplication Swift Medium 406 Queue Reconstruction by Height Swift Medium 419 Battleships in a Board Swift Medium 647 Palindromic Substrings Swift Medium 553 Optimal Division Swift Medium 413 Arithmetic Slices Swift Medium 739 Daily Temperatures Swift Medium 508 Most Frequent Subtree Sum Swift Medium 462 Minimum Moves to Equal Array Elements II Swift Medium 667 Beautiful Arrangement II Swift Medium 495 Teemo Attacking Swift Medium 451 Sort Characters By Frequency Swift Medium 655 Print Binary Tree Swift Medium 238 Product of Array Except Self Swift Medium 712 Minimum ASCII Delete Sum for Two Strings Swift Medium 725 Split Linked List in Parts Swift Medium 565 Array Nesting Swift Medium 347 Top K Frequent Elements Swift Medium 672 Bulb Switcher II Swift Medium 94 Binary Tree Inorder Traversal Swift Medium 477 Total Hamming Distance Swift Medium 503 Next Greater Element II Swift Medium 646 Maximum Length of Pair Chain Swift Medium 526 Beautiful Arrangement Swift Medium 454 4Sum II Swift Medium 421 Maximum XOR of Two Numbers in an Array Swift Medium 648 Replace Words Swift Medium 22 Generate Parentheses Swift Medium 39 Combination Sum Swift Medium 216 Combination Sum III Swift Medium 623 Add One Row to Tree Swift Medium 343 Integer Break Swift Medium 144 Binary Tree Preorder Traversal Swift Medium 498 Diagonal Traverse Swift Medium 2 Add Two Numbers Swift Medium 445 Add Two Numbers II Swift Medium 592 Fraction Addition and Subtraction Swift Medium 539 Minimum Time Difference Swift Medium 12 Integer to Roman Swift Medium 241 Different Ways to Add Parentheses Swift Medium 378 Kth Smallest Element in a Sorted Matrix Swift Medium 318 Maximum Product of Word Lengths Swift Medium 230 Kth Smallest Element in a BST Swift Medium 650 2 Keys Keyboard Swift Medium 392 Is Subsequence Swift Medium 423 Reconstruct Original Digits from English Swift Medium 583 Delete Operation for Two Strings Swift Medium 337 House Robber III Swift Medium 287 Find the Duplicate Number Swift Medium 78 Subsets Swift Medium 740 Delete and Earn Swift Medium 791 Custom Sort String Swift Medium 547 Friend Circles Swift Medium 763 Partition Labels Swift Medium 494 Target Sum Swift Medium 524 Longest Word in Dictionary through Deleting Swift Medium 46 Permutations Swift Medium 229 Majority Element II Swift Medium 319 Bulb Switcher Swift Medium 424 Longest Repeating Character Replacement Swift Medium 377 Combination Sum IV Swift Medium 137 Single Number II Swift Medium 516 Longest Palindromic Subsequence Swift Medium 89 Gray Code Swift Medium 328 Odd Even Linked List Swift Medium 102 Binary Tree Level Order Traversal Swift Medium 394 Decode String Swift Medium 48 Rotate Image Swift Medium 199 Binary Tree Right Side View Swift Medium 390 Elimination Game Swift Medium 636 Exclusive Time of Functions Swift Medium 684 Redundant Connection Swift Medium 96 Unique Binary Search Trees Swift Medium 62 Unique Paths Swift Medium 807 Max Increase to Keep City Skyline Swift Medium 309 Best Time to Buy and Sell Stock with Cooldown Swift Medium 692 Top K Frequent Words Swift Medium 525 Contiguous Array Swift Medium 77 Combinations Swift Medium 435 Non-overlapping Intervals Swift Medium 59 Spiral Matrix II Swift Medium 64 Minimum Path Sum Swift Medium 153 Find Minimum in Rotated Sorted Array Swift Medium 738 Monotone Increasing Digits Swift Medium 3 Longest Substring Without Repeating Characters Swift Medium 5 Longest Palindromic Substring Swift Medium 6 ZigZag Conversion Swift Medium 535 Encode and Decode TinyURL Objective-C Medium