Checkpoint — The Living Maximum

Checkpoint — The Living Maximum. Interleaved point-updates and range- max queries: static prefix arrays die at the first update; the honest structure is an iterative segment tree (O((n + q) log n)). The W is the instructive baseline: fully correct, passes every small test, and dies at full scale because O(n·q) = 4·10^10. This module's contract: when the W fails only on the big test, the lesson is the complexity family — the code was never the point.