CustomCC0-1.0#cp017-611400
Minimal Segment Tree Value Flip
Summary
- •Phase 5 / greedy, intervals
- •Reasoning-first competitive programming drill
Problem Description
Given an array of n bits (0 or 1), you may flip any contiguous segment (change all 0s to 1s and vice versa) in one move. Find the least moves to make the entire array all 1s.
How to read this problem in plain language:
- This is a Phase 5 reasoning drill focused on greedy, intervals.
- Typical lenses to test first: greedy, intervals, bits.
- Constraints reminder: 1 <= n <= 2*10^5
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 <= 2*10^5
Analysis
Key Insight
The goal is to force explicit intermediate reasoning before revealing more.
greedyintervalsbits