Combinatorics Topic Summary
A summary of basic combinatorics compiled while preparing for the Lanqiao Cup National Finals, covering modular inverses, binomial-coefficient templates, deran…
Lanqiao Cup 2026 Provincial Group B Review: Preparation, Contest Decisions, and Post-Contest Rework
A complete review of Lanqiao Cup 2026 Provincial Group B, from preparation and contest decisions to redoing the problems afterward, examining in-contest thinki…