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📜 WAYPOINT LESSON

Contest 1-A: Fever Chart

⭐ beginner⏳ 40 min read📍 Lesson 191 of 281

Mock contest 1, problem A: lazy range-add/range-sum. Target: solved within 40 minutes.

Contest 1-A — Fever Chart. Lazy propagation with ADD tags only: the tag must multiply by segment length when applied to a node's sum. Graded near-miss: the tag applied without the length factor.

Contest 1-A. Range add, range sum with a lazy segment tree. The apply step is sm += v * len. The graded wrong version adds v alone, so every range add lands short — most visible on the very first full-range add.