Segment tree: range queries and point updates for sum, min, or max in O(log n).

A segment tree answers any associative range query (sum, min, max, gcd) with point or range updates in O(log n). The signal is the recursive split into covered, disjoint, and partial nodes, plus lazy propagation for range updates. Here is the answer.

Updated Aug 2026 · Grounded in real Applied AI Engineer interview loops and written to a senior-engineer editorial bar.