CustomCC0-1.0#p0182150
Balanced Subtree Queries
Summary
- •Phase 1 / tree, dfs, dp
- •Reasoning-first competitive programming drill
Problem Description
You are given a rooted tree with n nodes, each node labeled 0 or 1. For q queries of form v, report the size of the largest subtree rooted at a descendant of v (including v) that has an equal number of 0s and 1s.
How to read this problem in plain language:
- This is a Phase 1 reasoning drill focused on tree, dfs, dp.
- Typical lenses to test first: tree, dp, dfs.
- Constraints reminder: 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
- •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.
treedpdfssubtree