CustomCC0-1.0#P004-7041850
Subset XOR Reversal
Summary
- •Phase 5 / greedy/xor/array_manipulation
- •Reasoning-first competitive programming drill
Problem Description
Given an array of N integers, determine the minimum number of (possibly overlapping) subarrays you must reverse so that the total XOR of the array equals 0.
How to read this problem in plain language:
- This is a Phase 5 reasoning drill focused on greedy/xor/arra.
- Typical lenses to test first: XOR, greedy, array.
- Constraints reminder: 1 ≤ 0 ≤ A[i] < 2^{20}
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 ≤ 0 ≤ A[i] < 2^{20}
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.
XORgreedyarray