1 Merge Intervals Array Sorting
Medium 100
0.5% 2 Remove All Adjacent Duplicates In String String Stack
Easy 91
0.7% 3 Search in Rotated Sorted Array Array Binary Search
Medium 90
0.5% 4 Vowel Spellchecker Array Hash Table String
Medium 89
0.6% 5 Insert Delete GetRandom O(1) Array Hash Table Math Design Randomized
Medium 89
0.6% 6 Remove All Adjacent Duplicates in String II String Stack
Medium 87
0.6% 7 Climbing Stairs Math Dynamic Programming Memoization
Easy 84
0.5% 8 Repeated DNA Sequences Hash Table String Bit Manipulation Sliding Window Rolling Hash Hash Function
Medium 80
0.5% 9 Sqrt(x) Math Binary Search
Easy 78
0.4% 10 Generate Parentheses String Dynamic Programming Backtracking
Medium 75
0.8% 11 Perfect Number Math
Easy 73
0.5% 12 Logger Rate Limiter Hash Table Design Data Stream
Easy 73
0.8% 13 Sum of Left Leaves Tree Depth-First Search Breadth-First Search Binary Tree
Easy 73
0.6% 14 Search Insert Position Array Binary Search
Easy 66
0.5% 15 Non-overlapping Intervals Array Dynamic Programming Greedy Sorting
Medium 66
0.6% 16 Evaluate Reverse Polish Notation Array Math Stack
Medium 61
0.6% 17 Two Best Non-Overlapping Events Array Binary Search Dynamic Programming Sorting Heap (Priority Queue)
Medium 61
0.6% 18 Word Break II Array Hash Table String Dynamic Programming Backtracking Trie Memoization
Hard 55
0.6% 19 Word Search Array String Backtracking Depth-First Search Matrix
Medium 55
0.5% 20 Implement Trie (Prefix Tree) Hash Table String Design Trie
Medium 55
0.7% 21 Check If a String Contains All Binary Codes of Size K Hash Table String Bit Manipulation Rolling Hash Hash Function
Medium 55
0.6% 22 Minimum Substring Partition of Equal Character Frequency Hash Table String Dynamic Programming Counting
Medium 55
0.4% 23 Word Break Array Hash Table String Dynamic Programming Trie Memoization
Medium 46
0.5% 24 Number of Islands Array Depth-First Search Breadth-First Search Union-Find Matrix
Medium 46
0.6% 25 Special Binary String String Divide and Conquer Sorting
Hard 46
0.8% 26 Decode the Slanted Ciphertext String Simulation
Medium 46
0.7% 27 Maximum Palindromes After Operations Array Hash Table String Greedy Sorting Counting
Medium 46
0.5% 28 Trapping Rain Water Array Two Pointers Dynamic Programming Stack Monotonic Stack
Hard 46
0.7% 29 Unique Paths Math Dynamic Programming Combinatorics
Medium 46
0.7% 30 Recover a Tree From Preorder Traversal String Tree Depth-First Search Binary Tree
Hard 46
0.8%