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algorithm - Efficiently determining the largest minimum cost to travel from a fixed source to an arbitrary sink in a weighted graph


Let vi be a vertex in a graph G with vertices (v1,...,vN)V and edges (e1,...,eM)E with associated weights (w1,...,wM). Let vsV be specified vertex in the graph. In Mathematica 9, beyond repeatedly applying Dijkstra's algorithm by way of FindShortestPath[] and then summing the weights along the edges of each path, is there an efficient way to return the set of minimum costs to travel from vs to all other vertices vivs?


Also, other than finding the maximum value of this matrix, is there an efficient way to detect if one path exists where the minimum cost exceeds some threshold T?



Answer



You could use GraphDistance function to get distances from the given vertex to all others:



g = PolyhedronData["Dodecahedron", "SkeletonGraph"];
w = RandomInteger[{0, 10}, EdgeCount[g]];
wg = SetProperty[g, EdgeWeight -> w];

In[10]:= GraphDistance[wg, 1]
Out[10]= {0, 24., 14., 11., 21., 15., 10., 10., 7., 4., 14., 14.,
21., 6., 3., 5., 11., 14., 18., 12.}

If you want to find the maximum value (the length of the longest shortest path), you can use VertexEccentricity function:


In[11]:= VertexEccentricity[wg, 1]

Out[11]= 24.

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