CustomCC0-1.0#ct-p2-021650
Color Teleport BFS
Summary
- •Phase 2 / bfs-state-model
- •Reasoning-first competitive programming drill
Problem Description
On an unweighted graph, each node has a color. You may teleport once per color to any node of same color. Find shortest path from s to t.
How to read this problem in plain language:
- This is a Phase 2 reasoning drill focused on bfs-state-model.
- Typical lenses to test first: graph, bfs, state-modeling.
- Constraints reminder: 1 <= n,m <= 2e5
Mini examples for mental simulation:
1) Boundary example: Distance is zero immediately. Explain expected behavior and why naive logic may fail.
2) Adversarial example: Return -1 when unreachable even with teleports.
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,m <= 2e5
Analysis
Key Insight
Quantifying complexity against constraints is mandatory for selecting the final approach and rejecting brute force formally.
graphbfsstate-modeling