# Editing Floyd–Warshall algorithm

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==Warshall's algorithm== | ==Warshall's algorithm== | ||

− | A special case of the Floyd–Warshall algorithm is ''Warshall's algorithm'', which tests only for reachability | + | A special case of the Floyd–Warshall algorithm is ''Warshall's algorithm'', which tests only for reachability. If two vertices are linked by an edge, we assign the edge any finite weight (such as 0 or 1), otherwise we assign it an infinite weight. If, at the end, we find the distance from one vertex to another to be finite, then they are connected, since a path existed using only finite-weight edges (that is, ones that actually exist); otherwise, if no such path exists, the entry in the matrix will be infinity. Notice that we can replace "finite" by 1, "infinite" by 0, addition with logical AND, and <code>min</code> with logical OR, and preserve existing logic. This yields the following implementation of Warshall's algorithm: |

<pre> | <pre> | ||

input adj | input adj |