CustomCC0-1.0#cp0182100
Colorful Path Queries
Summary
- •Phase 6 / tree, lca, path, color counting
- •Reasoning-first competitive programming drill
Problem Description
Given a tree with n nodes, each edge colored with a color. For q queries, each asks for the number of unique colors along the path between two nodes u and v.
How to read this problem in plain language:
- This is a Phase 6 reasoning drill focused on tree, lca, path, color counting.
- Typical lenses to test first: tree, lca, color.
- Constraints reminder: 1 ≤ n, 1 ≤
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, 1 ≤
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.
treelcacoloroffline query