📜 WAYPOINT LESSON
Checkpoint — The Amnesiac Stack
⭐⭐⭐ advanced⏳ 25 min read📍 Lesson 245 of 281
Min-stack protocol: pair (value, min-so-far) restores the minimum on every pop. The W is the classic single-variable min that never comes back — the amnesia the pop-heavy test exposes.
Checkpoint — The Amnesiac Stack. The min-stack is the canonical 'carry the aggregate in the state' structure: each stack entry stores (value, min-from-bottom-to-here), so a pop restores the previous minimum automatically. The W keeps a single global min variable and never restores it — after the minimum is popped, every future ask reports a value that is no longer in the stack. The pop-heavy test is the harness discipline made concrete: trace pops twice before trusting.