UVa 627 - The Net

Summary
Given a set of routers (nodes) (where $$2 \leq N \leq 300$$), for a set of queries, find the shortest path.

Explanation
Since $$N \leq 300$$, Floyd-Warshall's Algorithm is out of the way. Still, an $$O(N^2)$$ algorithm is suffice for this problem - use breadth-first search.

Gotchas

 * Any points one can easily overlook?
 * The correct way to understand ambiguous formulations?

Implementations
Notes/Hints on actual implementation here.

Optimizations
Optimizations here.

Input
6 1-2,3,4 2-1,3 3-1,2,5,6 4-1,5 5-3,4,6 6-3,5 6 1 6 1 5 2 4 2 5 3 6 2 1 10 1-2 2- 3-4 4-8 5-1 6-2 7-3,9 8-10 9-5,6,7 10-8 3 9 10 5 9 9 2

Output
- 1 3 6 1 3 5 2 1 4 2 3 5 3 6 2 1 - 9 7 3 4 8 10 connection impossible 9 6 2