Checkpoint — The Label-Free Gauntlet

Điểm kiểm tra — Rào không nhãn. No topic in the statement. The constraint column (n ≤ 2·10⁵, both-side dominance queries) is the only signal: a static range-max structure. Building the sparse table is the easy half; handling d = min(i−1, n−i) boundaries is the half that costs points. The wrong solution looks identical and differs by one comparison operator — exactly the kind of bug the stress-testing habit from Module 6 catches in minutes.