Floyd-Warshall (vectorized)

Vectorized Floyd-Warshall algorithm to find shortest paths and distances between every node pair.

-- The input weight (or initial distance) matrix must have Inf values where the nodes aren't connected and 0's on the diagonal.
-- Outputs are the shortpaths' distance matrix D, and predecessor's matrix P such that P(i,j) is the node before j on the shortest path from i to j, so if you want to build the paths you have to read P backwards.
Hope it helps!