Editorial for Mock CCC '18 Contest 1 S4 - A Graph Problem

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Author: xiaowuc1

The most straightforward solution is to construct each graph and then do a BFS from S to T. This runs in \mathcal O(K(N+M)) time.

We can reduce this to \mathcal O(M^2) time by noticing that there are only \mathcal O(M) relevant graphs to construct - namely when an edge becomes eligible or when an edge becomes unavailable.


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