CustomCC0-1.0#cpq012-7101620

Monotonic Stack Range Count

Summary

•Phase 2 / monotonic-stack, subarray
•Reasoning-first competitive programming drill

Problem Description

Given an array A of N integers, count the total number of subarrays where the minimum element is on the leftmost side or the maximum on the rightmost side. How to read this problem in plain language: - This is a Phase 2 reasoning drill focused on monotonic-stack, subarray. - Typical lenses to test first: monotonic-stack, subarray. - Constraints reminder: 1 <= N <= 3e5; 1 <=

A_{i}

<= 1e9 Mini examples for mental simulation: 1) Boundary example: Describe why this case is tricky. Explain expected behavior and why naive logic may fail. 2) Adversarial example: Adversarial case where naive greedy/local decision looks correct but fails globally. Lite-mode writing target: - Write 1~2 observations that shrink the search space. - Name one final algorithm and state target complexity explicitly. - Validate with at least 2 edge cases and one hand simulation.

Constraints

•
1 <= N <= 3e5; 1 <= $A_{i}$ <= 1e9

Analysis

Key Insight

Use this hint to refine your reasoning. This step should reduce search space or formalize correctness. State why this insight changes your algorithm choice.

monotonic-stacksubarray