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Problems > Sum of Every Minimum > Editorial

Sum of Every Minimum — Solution & Editorial

Back to the Problem

Each ai is the minimum of (distance to previous strictly-smaller) × (distance to next smaller-or-equal) subarrays. Monotonic stacks compute both boundaries; sum ai·left·right. The strict/non-strict asymmetry avoids double-counting equal values.

Complexity: O(N)

Watch out: Equal elements: one side must use strict and the other non-strict comparison, or subarrays are counted twice or zero times.