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Find all-pairs shortest path lengths using Floyd’s algorithm.
G : NetworkX graph
weight: string, optional (default= ‘weight’)
Edge data key corresponding to the edge weight.
predecessor,distance : dictionaries
Dictionaries, keyed by source and target, of predecessors and distances in the shortest path.
Floyd’s algorithm is appropriate for finding shortest paths in dense graphs or graphs with negative weights when Dijkstra’s algorithm fails. This algorithm can still fail if there are negative cycles. It has running time O(n^3) with running space of O(n^2).