1 Two Sum 23.0% Easy 2 Add Two Numbers 23.0% Medium 3 Longest Substring Without Repeating Characters 21.9% Medium 5 Longest Palindromic Substring 23.0% Medium 8 String to Integer (atoi) 13.5% Easy 15 3Sum 18.8% Medium 17 Letter Combinations of a Phone Number 28.6% Medium 20 Valid Parentheses 29.3% Easy 21 Merge Two Sorted Lists 35.4% Easy 23 Merge k Sorted Lists 23.3% Hard 42 Trapping Rain Water 32.2% Hard 48 Rotate Image 34.6% Medium 49 Group Anagrams 27.4% Medium 78 Subsets 31.3% Medium 89 Gray Code 36.3% Medium 98 Validate Binary Search Tree 20.9% Medium 102 Binary Tree Level Order Traversal 32.7% Easy 121 Best Time to Buy and Sell Stock 36.0% Easy 126 Word Ladder II 13.6% Hard 127 Word Ladder 19.6% Medium 138 Copy List with Random Pointer 26.1% Hard 139 Word Break 25.2% Medium 141 Linked List Cycle 37.0% Medium 146 LRU Cache 15.8% Hard 155 Min Stack 22.0% Easy 160 Intersection of Two Linked Lists 30.2% Easy 167 Two Sum II - Input array is sorted 47.8% Medium 186 Reverse Words in a String II 29.1% Medium 199 Binary Tree Right Side View 34.3% Medium 200 Number of Islands 27.6% Medium 204 Count Primes 24.2% Easy 206 Reverse Linked List 39.4% Easy 215 Kth Largest Element in an Array 33.1% Medium 234 Palindrome Linked List 28.0% Easy 235 Lowest Common Ancestor of a Binary Search Tree 37.7% Easy 236 Lowest Common Ancestor of a Binary Tree 28.8% Medium 238 Product of Array Except Self 42.6% Medium 239 Sliding Window Maximum 27.3% Hard 240 Search a 2D Matrix II 34.4% Medium 242 Valid Anagram 41.7% Easy 297 Serialize and Deserialize Binary Tree 27.8% Hard
1 Two Sum 23.0% Easy 2 Add Two Numbers 23.0% Medium 3 Longest Substring Without Repeating Characters 21.9% Medium 5 Longest Palindromic Substring 23.0% Medium 8 String to Integer (atoi) 13.5% Easy 15 3Sum 18.8% Medium 17 Letter Combinations of a Phone Number 28.6% Medium 20 Valid Parentheses 29.3% Easy 21 Merge Two Sorted Lists 35.4% Easy 23 Merge k Sorted Lists 23.3% Hard 42 Trapping Rain Water 32.2% Hard 48 Rotate Image 34.6% Medium 49 Group Anagrams 27.4% Medium 78 Subsets 31.3% Medium 89 Gray Code 36.3% Medium 98 Validate Binary Search Tree 20.9% Medium 102 Binary Tree Level Order Traversal 32.7% Easy 121 Best Time to Buy and Sell Stock 36.0% Easy 126 Word Ladder II 13.6% Hard 127 Word Ladder 19.6% Medium 138 Copy List with Random Pointer 26.1% Hard 139 Word Break 25.2% Medium 141 Linked List Cycle 37.0% Medium 146 LRU Cache 15.8% Hard 155 Min Stack 22.0% Easy 160 Intersection of Two Linked Lists 30.2% Easy 167 Two Sum II - Input array is sorted 47.8% Medium 186 Reverse Words in a String II 29.1% Medium 199 Binary Tree Right Side View 34.3% Medium 200 Number of Islands 27.6% Medium 204 Count Primes 24.2% Easy 206 Reverse Linked List 39.4% Easy 215 Kth Largest Element in an Array 33.1% Medium 234 Palindrome Linked List 28.0% Easy 235 Lowest Common Ancestor of a Binary Search Tree 37.7% Easy 236 Lowest Common Ancestor of a Binary Tree 28.8% Medium 238 Product of Array Except Self 42.6% Medium 239 Sliding Window Maximum 27.3% Hard 240 Search a 2D Matrix II 34.4% Medium 242 Valid Anagram 41.7% Easy 297 Serialize and Deserialize Binary Tree 27.8% Hard