New subject: [Boost-Users] Re: Is bellman_ford_shortest_paths supposed to work for undirected graphs?

25 Jul 2002

      int main()
{
    enum {A,B,Z};
    char const name[] = "ABZ";

    int const numVertex = static_cast<int>(Z);

    typedef std::pair Edge;

    Edge edge_array[] = {Edge(B,A)};

    int const numEdges = sizeof(edge_array) / sizeof(Edge);

    int const weight[numEdges] = {11};

    typedef
adjacency_list
...
Graph;
Graph g(edge_array, edge_array + numEdges, numVertex);

    Graph::edge_iterator ei, ei_end;
    property_map::type weight_pmap = get(edge_weight,
g);

    int i = 0;
    for(tie(ei, ei_end) = edges(g); ei != ei_end; ++ei, ++i)
    {
        weight_pmap[*ei] = weight[i];
    }

    std::vector<int> parent(numVertex);
    for(i = 0; i < numVertex; ++i)
    {
        parent[i] = i;
    }

    std::vector<int> distance(numVertex, std::numeric_limits<int>::max());
    distance[A] = 0; // Set source distance to zero

    bool const r = bellman_ford_shortest_paths(g, int (numVertex),
weight_map(weight_pmap).distance_map(&distance[0]).
                               predecessor_map(&parent[0]));

    if (r)
    {
        for(int i = 0; i < numVertex; ++i)
        {
            std::cout << name[i] << ": " << std::setw(3) << distance[i]
            << " " << name[parent[i]] << std::endl;
        }
    }
    else
    {
        std::cout << "negative cycle" << std::endl;
    }

    return EXIT_SUCCESS;
}

Expected Output:-
A:   0 A
B:  11 A

Actual Output:-
A:   0 A
B: 2147483647 B

Louis.

Is bellman_ford_shortest_paths supposed to work for undirected graphs?

Louis Lavery

Matthias Kronenberger

Jeremy Siek

Jeremy Siek

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participants (3)