leetcode Top 150 - Easy + Medium Number Problem Name Solution 1 Two Sum Two Sum 2 Valid Palindrome Valid Palindrome 3 3sum 3sum 4 Remove Element Remove Element 5 Remove Duplicates from Sorted Array Remove Duplicates 6 Remove Duplicates from Sorted Array II Remove Duplicates II 7 Majority Element Majority Element 8 Merge Sorted Array Merge Sorted Array 9 Best Time to Buy and Sell Stock Stock I 10 Roman to Integer Roman to Integer 11 Is Subsequence Is Subsequence 12 Valid Parentheses Valid Parentheses 13 Valid Anagram Valid Anagram 14 Plus One Plus One 15 Palindrome Number Palindrome Number 16 Single Number Single Number 17 Ransom Note Ransom Note 18 Longest Common Prefix Longest Common Prefix 19 Length of Last Word Length of Last Word 20 Isomorphic Strings Isomorphic Strings 21 Happy Number Happy Number 22 Word Pattern Word Pattern 23 Contains Duplicate II Contains Duplicate II 24 Sqrt(x) Sqrt(x) 25 Number of 1 Bits Number of 1 Bits 26 Find the Index of the First Occurrence in a String Find the Index of the First Occurrence in a String 27 Reverse Bits Reverse Bits 28 Add Binary Add Binary 29 Search Insert Position Search Insert Position 30 Group Anagrams Group Anagrams 31 Summary Ranges Summary Ranges 32 Longest Consecutive Sequence Longest Consecutive Sequence 33 Evaluate Reverse Polish Notation Evaluate Reverse Polish Notation 34 Min Stack Min Stack 35 Simplify Path Simplify Path 36 Basic Calculator Basic Calculator 37 Container With Most Water Container With Most Water 38 Two Sum II - Input Array Is Sorted Two Sum II - Input Array Is Sorted 39 Pow(x, n) Pow(x, n) 40 Factorial Trailing Zeroes Factorial Trailing Zeroes 41 Best Time to Buy and Sell Stock II Best Time to Buy and Sell Stock II 42 Product of Array Except Self Product of Array Except Self 43 Maximum Subarray Maximum Subarray 44 Maximum Sum Circular Subarray Maximum Sum Circular Subarray 45 Reverse Words in a String Reverse Words in a String 46 Linked List Cycle Linked List Cycle 47 Add Two Numbers Add Two Numbers 48 Insert Delete GetRandom O(1) Insert Delete GetRandom O(1) 49 Rotate Array Rotate Array 50 Jump Game Jump Game 51 Jump Game II Jump Game II 52 LRU Cache LRU Cache 53 Top K Frequent Elements Top K Frequent Elements 54 String Encode and Decode String Encode and Decode 55 Valid Sudoku Valid Sudoku Top 150 - Hard Number Problem Name Solution 1 Max Points on a Line Max Points on a Line 2 Trapping Rain Water Trapping Rain Water