📜 WAYPOINT LESSON
Simulation II — The Vanishing Sums
⭐⭐⭐ advanced⏳ 25 min read📍 Lesson 249 of 281
Hidden-topic problem: count zero-sum subarrays. The small value range is a deliberate gift — read the constraint table as a hint machine.
Simulation II. No topic announced. The value bound (−5..5) is the invitation: some counting structure over the reachable prefix sums beats any pairwise scan. The all-zeros test pins the empty/degenerate boundary.