Array

Medium | Array, Dynamic Programming, Prefix Sum

Easy | Array, Two Pointers, String

Medium | Array, Greedy, Heap (Priority Queue)

Hard | Array, Binary Search, Binary Indexed Tree

Easy | Array, String

Medium | Array, Greedy, Sorting

Hard | Array, Binary Search, Depth-First Search, Breadth-First Search, Union-Find, Matrix

Medium | Array, Greedy, Matrix

Easy | Array, Math, Number Theory

Medium | Array, Hash Table, String, Backtracking