Array

Medium | Array, Hash Table, Two Pointers, Sorting

Easy | Array, String

Medium | Array, Greedy, Graph Theory, Sorting, Heap (Priority Queue)

Medium | Array, Binary Search, Greedy

Hard | Array, Hash Table, Greedy, Counting

Easy | Array, Sorting, Heap (Priority Queue), Matrix, Simulation

Medium | Array, Hash Table, Binary Search, Dynamic Programming, Sorting

Medium | Array, Hash Table, Design, Simulation

Hard | Array, Two Pointers, Breadth-First Search, Union-Find, Sorting, Heap (Priority Queue), Matrix

Easy | Array, Hash Table, String, Bit Manipulation, Counting