LeetCode LeetCode Algorithm # Title Solution Difficulty 1 Two Sum C Easy 2 Add Two Numbers C Medium 3 Longest Substring Without Repeating Characters C Medium 4 Median of Two Sorted Arrays C Hard 5 Longest Palindromic Substring C Medium 6 Zigzag Conversion C Medium 7 Reverse Integer C Medium 8 String to Integer (atoi) C Medium 9 Palindrome Number C Easy 10 Regular Expression Matching C Hard 11 Container With Most Water C Medium 12 Integer to Roman C Medium 13 Roman to Integer C Easy 14 Longest Common Prefix C Easy 16 3Sum Closest C Medium 17 Letter Combinations of a Phone Number C Medium 19 Remove Nth Node From End of List C Medium 20 Valid Parentheses C Easy 21 Merge Two Sorted Lists C Easy 24 Swap Nodes in Pairs C Medium 26 Remove Duplicates from Sorted Array C Easy 27 Remove Element C Easy 28 Find the Index of the First Occurrence in a String C Easy 29 Divide Two Integers C Medium 32 Longest Valid Parentheses C Hard 35 Search Insert Position C Easy 37 Sudoku Solver C Hard 38 Count and Say C Medium 42 Trapping Rain Water C Hard 45 Jump Game II C Medium 50 Pow(x, n) C Medium 53 Maximum Subarray C Medium 62 Unique Paths C Medium 63 Unique Paths II C Medium 66 Plus One C Easy 75 Sort Colors C Medium 79 Word Search C Medium 82 Remove Duplicates from Sorted List II C Medium 83 Remove Duplicates from Sorted List C Easy 94 Binary Tree Inorder Traversal C Easy 98 Validate Binary Search Tree C Medium 101 Symmetric Tree C Easy 104 Maximum Depth of Binary Tree C Easy 108 Convert Sorted Array to Binary Search Tree C Easy 109 Convert Sorted List to Binary Search Tree C Medium 110 Balanced Binary Tree C Easy 112 Path Sum C Easy 118 Pascal's Triangle C Easy 119 Pascal's Triangle II C Easy 121 Best Time to Buy and Sell Stock C Easy 124 Binary Tree Maximum Path Sum C Hard 125 Valid Palindrome C Easy 136 Single Number C Easy 141 Linked List Cycle C Easy 142 Linked List Cycle II C Medium 153 Find Minimum in Rotated Sorted Array C Medium 160 Intersection of Two Linked Lists C Easy 169 Majority Element C Easy 173 Binary Search Tree Iterator C Medium 189 Rotate Array C Medium 190 Reverse Bits C Easy 191 Number of 1 Bits C Easy 201 Bitwise AND of Numbers Range C Medium 203 Remove Linked List Elements C Easy 206 Reverse Linked List C Easy 215 Kth Largest Element in an Array C Medium 217 Contains Duplicate C Easy 223 Rectangle Area C Medium 226 Invert Binary Tree C Easy 230 Kth Smallest Element in a BST C Medium 231 Power of Two C Easy 234 Palindrome Linked List C Easy 236 Lowest Common Ancestor of a Binary Tree C Medium 242 Valid Anagram C Easy 268 Missing Number C Easy 274 H-Index C Medium 278 First Bad Version C Easy 283 Move Zeroes C Easy 287 Find the Duplicate Number C Medium 344 Reverse String C Easy 367 Valid Perfect Square C Easy 387 First Unique Character in a String C Easy 389 Find the Difference C Easy 404 Sum of Left Leaves C Easy 434 Number of Segments in a String C Easy 442 Find All Duplicates in an Array C Medium 461 Hamming Distance C Easy 476 Number Complement C Easy 485 Max Consecutive Ones C Easy 509 Fibonacci Number C Easy 520 Detect Capital C Easy 540 Single Element in a Sorted Array C Medium 561 Array Partition C Easy 567 Permutation in String C Medium 617 Merge Two Binary Trees C Easy 647 Palindromic Substrings C Medium 669 Trim a Binary Search Tree C Medium 674 Longest Continuous Increasing Subsequence C Easy 684 Redundant Connection C Medium 700 Search in a Binary Search Tree C Easy 701 Insert into a Binary Search Tree C Medium 704 Binary Search C Easy 709 To Lower Case C Easy 771 Jewels and Stones C Easy 807 Max Increase to Keep City Skyline C Medium 841 Keys and Rooms C Medium 852 Peak Index in a Mountain Array C Medium 876 Middle of the Linked List C Easy 901 Online Stock Span C Medium 905 Sort Array By Parity C Easy 917 Reverse Only Letters C Easy 931 Minimum Falling Path Sum C Medium 938 Range Sum of BST C Easy 953 Verifying an Alien Dictionary C Easy 965 Univalued Binary Tree C Easy 977 Squares of a Sorted Array C Easy 979 Distribute Coins in Binary Tree C Medium 985 Sum of Even Numbers After Queries C Medium 997 Find the Town Judge C Easy 1008 Construct Binary Search Tree from Preorder Traversal C Medium 1009 Complement of Base 10 Integer C Easy 1019 Next Greater Node In Linked List C Medium 1026 Maximum Difference Between Node and Ancestor C Medium 1089 Duplicate Zeros C Easy 1137 N-th Tribonacci Number C Easy 1147 Longest Chunked Palindrome Decomposition C Hard 1184 Distance Between Bus Stops C Easy 1189 Maximum Number of Balloons C Easy 1207 Unique Number of Occurrences C Easy 1283 Find the Smallest Divisor Given a Threshold C Medium 1524 Number of Sub-arrays With Odd Sum C Medium 1653 Minimum Deletions to Make String Balanced C Medium 1657 Determine if Two Strings Are Close C Medium 1695 Maximum Erasure Value C Medium 1704 Determine if String Halves Are Alike C Easy 1752 Check if Array Is Sorted and Rotated C Easy 1769 Minimum Number of Operations to Move All Balls to Each Box C Medium 1833 Maximum Ice Cream Bars C Medium 1838 Frequency of the Most Frequent Element C Medium 2024 Maximize the Confusion of an Exam C Medium 2095 Delete the Middle Node of a Linked List C Medium 2125 Number of Laser Beams in a Bank C Medium 2130 Maximum Twin Sum of a Linked List C Medium 2222 Number of Ways to Select Buildings C Medium 2256 Minimum Average Difference C Medium 2270 Number of Ways to Split Array C Medium 2279 Maximum Bags With Full Capacity of Rocks C Medium 2304 Minimum Path Cost in a Grid C Medium 2482 Difference Between Ones and Zeros in Row and Column C Medium 2501 Longest Square Streak in an Array C Medium