CustomCC0-1.0#cp0021900
Graph Shortest Path with Parity Constraint
Summary
- •Phase 6 / graphs, shortest paths, parity
- •Reasoning-first competitive programming drill
Problem Description
Given a directed graph with n nodes and m edges, each edge has a weight. Find the shortest path from node 1 to n such that the sum of the weights along the path is even.
How to read this problem in plain language:
- This is a Phase 6 reasoning drill focused on graphs, shortest paths, parity.
- Typical lenses to test first: graphs, dijkstra, parity.
- Constraints reminder: 2 ≤ 1 ≤ 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
- •2 ≤ 1 ≤ 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.
graphsdijkstraparityshortest path