AtCoder ABC457-E Review: Interval Unions, Structural Cases, and an Offline Fenwick Tree
A review of exact coverage by interval unions. Model two pieces of cloth covering a query interval exactly as an interval-union test, split valid arrangements…
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…