Problems

Very easy · Math

Very easy · Implementation

Easy · Hashing

Very easy · Sorting · Hashing

Easy · Sorting · Data Structures

Very easy · Implementation

Very easy · Implementation

Very hard · Bitmasks · Dynamic programming · Graph matchings · Combinatorics

Easy · Depth-first Search

Very hard · Dynamic programming · Strings · Greedy algorithms · Prefix Function

Very hard · Data Structures · Disjoint set union · Graphs · Divide and Conquer · Segment Tree

Easy · Breadth-first Search

Hard · Geometry · Trees · Constructive Algorithms · Depth-first Search · Sorting

Easy · Prefix Sums

Hard · Dynamic programming · Prefix Sums

Medium · String suffix structures · Strings

Very hard · Divide and Conquer · Sparse Table · Binary Search · Range queries · Number theory

Very easy · Graphs

Hard · Number theory · Math · Prefix Sums

Medium · Greedy algorithms · Bitwise Operations

Very hard · Strings · Prefix Function · Matrix · Dynamic programming

Very easy · Strings · Brute force

Easy · Implementation

Hard · Graphs · Greedy algorithms · Sorting