Problems

Very easy · Sorting · Greedy algorithms

Very easy · Brute force · String suffix structures

Very easy · Graphs

Easy · Implementation

Medium · Greedy algorithms · Sorting · Geometry

Hard · Dynamic programming · Combinatorics · Number theory

Easy · Graphs · Shortest paths

Very easy · Dynamic programming · Prefix Sums

Hard · Trees · Depth-first Search · Combinatorics · Prefix Sums · Binary Search

Very hard · Dynamic programming · Combinatorics · Greedy algorithms · Number theory · Stacks

Very easy · Implementation

Very easy · Implementation · Graphs

Medium · Greedy algorithms · Prefix Sums

Medium · Sorting · Greedy algorithms

Very easy · Prefix Sums · Implementation

Easy · Graphs · Disjoint set union

Very easy · Binary Search · Data Structures · Dynamic programming

Very hard · Binary Search · Data Structures · Greedy algorithms · Sorting

Very hard · Prefix Sums · Dynamic programming · Greedy algorithms · Scanline / Sweep Line

Easy · Prefix Sums · Dynamic programming

Very hard · Trees · Dynamic programming · Combinatorics · Depth-first Search · Number theory

Very hard · Dynamic programming · Dynamic Programming Optimization · Fenwick Tree · Segment Tree · Divide and Conquer

Very easy · Geometry

Very easy · Brute force

Very easy · Sorting · Greedy algorithms