Math and Geometry (S1)

Coordinate geometry, rectangles, polygons Modular arithmetic and large numbers

Sorting, Greedy and Searching (S2)

Greedy with sorting and exchange arguments Two pointers and sliding window Prefix sums and difference arrays II Binary search on the answer Hash maps and frequency counting

Brute Force and Data Structures (S3)

Complete search and bounds analysis Constructive algorithms Stacks and queues Priority queues and sets Disjoint Set Union

Strings and Graphs

String processing patterns BFS/DFS on structured graphs Trees and rooted traversal Functional graphs and cycle detection Counting and combinatorics

Sorting, Greedy and Searching (S2)

Binary search on the answer

occasional

Work in progress

This module is still being written — the content here is a placeholder. This guide is open source, and contributions are welcome.

Contribute on GitHub — help write this module by opening a pull request.

Prefix sums and difference arrays II

Prefix sums and difference arrays II — anchored on 2021 S2 *Modern Art* and 2026 S2 *Beams of Light*

Hash maps and frequency counting

Hash maps and frequency counting — anchored on 2022 J4/S2 *Good Groups* and 2016 S1 *Ragaman*

On this page

Binary search on the answer