CustomCC0-1.0#cpq006-6412200
Tree Branch Maximum Frequency
Summary
- •Phase 3 / tree, lca, frequency
- •Reasoning-first competitive programming drill
Problem Description
Given a rooted tree with N nodes and each node labeled with an integer, for Q queries (U, V), determine the integer label with the highest frequency along the path from U to V. If multiple, pick the smallest.
How to read this problem in plain language:
- This is a Phase 3 reasoning drill focused on tree, lca, frequency.
- Typical lenses to test first: tree, lca, frequency.
- Constraints reminder: 1 <= N, Q <= 1e5; |label| <= 1e9; 1 <= U, V <= 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
- •1 <= N, Q <= 1e5; |label| <= 1e9; 1 <= U, V <= 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.
treelcafrequencypath-query