CustomCC0-1.0#cpq0021500
Sum-Free Permutation
Summary
- •Phase 6 / greedy/array
- •Reasoning-first competitive programming drill
Problem Description
Given a permutation of 1..n, partition it into the minimum number of contiguous segments such that no segment contains two numbers whose sum is equal to n+1.
How to read this problem in plain language:
- This is a Phase 6 reasoning drill focused on greedy/array.
- Typical lenses to test first: greedy, partition, array.
- Constraints reminder: 2 ≤ , permutation of 1..n
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
- •2 ≤ , permutation of 1..n
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.
greedypartitionarray