Title Acceptance Level Best Time to Buy and Sell Stock II 57.0% Easy Best Time to Buy and Sell Stock 50.5% Easy Implement Queue using Stacks 49.6% Easy Climbing Stairs 47.8% Easy Maximum Product of Three Numbers 47.1% Easy Maximum Subarray 46.5% Easy Two Sum 45.6% Easy Implement Stack using Queues 45.1% Easy Find Pivot Index 44.0% Easy Valid Parentheses 39.0% Easy Implement strStr() 34.5% Easy Palindromic Substrings 60.6% Medium Different Ways to Add Parentheses 55.2% Medium Longest String Chain 54.7% Medium Binary Tree Level Order Traversal 54.6% Medium Binary Tree Right Side View 54.1% Medium Maximum Length of Repeated Subarray 49.4% Medium Construct Binary Tree from Preorder and Inorder Traversal 48.8% Medium Number of Islands 46.8% Medium Meeting Rooms II 45.7% Medium Knight Dialer 45.2% Medium Design Circular Queue 43.7% Medium Search a 2D Matrix II 43.2% Medium Inorder Successor in BST 40.4% Medium Maximal Square 37.7% Medium Reconstruct Itinerary 36.7% Medium LRU Cache 33.2% Medium 3Sum 26.8% Medium Reverse Words in a String 21.9% Medium String to Integer (atoi) 15.4% Medium Trapping Rain Water 48.9% Hard Serialize and Deserialize Binary Tree 47.5% Hard Find Median from Data Stream 44.3% Hard Longest Substring with At Most K Distinct Characters 44.1% Hard Sliding Window Maximum 43.0% Hard Maximal Rectangle 37.7% Hard Best Time to Buy and Sell Stock III 37.5% Hard Consecutive Numbers Sum 37.5% Hard Best Position for a Service Centre 35.9% Hard Word Search II 34.9% Hard Longest Valid Parentheses 28.4% Hard