Boost C++ Libraries

libs/graph/example/dijkstra-example-listS.cpp

//=======================================================================
// Copyright 2001 Jeremy G. Siek, Andrew Lumsdaine, Lie-Quan Lee,
//
// Distributed under the Boost Software License, Version 1.0. (See
// accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//=======================================================================
#include <boost/config.hpp>
#include <iostream>
#include <fstream>

#include <boost/graph/graph_traits.hpp>
#include <boost/graph/adjacency_list.hpp>
#include <boost/graph/dijkstra_shortest_paths.hpp>

using namespace boost;

int main(int, char*[])
{
    typedef adjacency_list_traits< listS, listS, directedS >::vertex_descriptor
        vertex_descriptor;
    typedef adjacency_list< listS, listS, directedS,
        property< vertex_index_t, int,
            property< vertex_name_t, char,
                property< vertex_distance_t, int,
                    property< vertex_predecessor_t, vertex_descriptor > > > >,
        property< edge_weight_t, int > >
        graph_t;
    typedef std::pair< int, int > Edge;

    const int num_nodes = 5;
    enum nodes
    {
        A,
        B,
        C,
        D,
        E
    };
    Edge edge_array[] = { Edge(A, C), Edge(B, B), Edge(B, D), Edge(B, E),
        Edge(C, B), Edge(C, D), Edge(D, E), Edge(E, A), Edge(E, B) };
    int weights[] = { 1, 2, 1, 2, 7, 3, 1, 1, 1 };
    int num_arcs = sizeof(edge_array) / sizeof(Edge);
    graph_traits< graph_t >::vertex_iterator i, iend;

    graph_t g(edge_array, edge_array + num_arcs, weights, num_nodes);
    property_map< graph_t, edge_weight_t >::type weightmap
        = get(edge_weight, g);

    // Manually intialize the vertex index and name maps
    property_map< graph_t, vertex_index_t >::type indexmap
        = get(vertex_index, g);
    property_map< graph_t, vertex_name_t >::type name = get(vertex_name, g);
    int c = 0;
    for (boost::tie(i, iend) = vertices(g); i != iend; ++i, ++c)
    {
        indexmap[*i] = c;
        name[*i] = 'A' + c;
    }

    vertex_descriptor s = vertex(A, g);

    property_map< graph_t, vertex_distance_t >::type d
        = get(vertex_distance, g);
    property_map< graph_t, vertex_predecessor_t >::type p
        = get(vertex_predecessor, g);
    dijkstra_shortest_paths(g, s, predecessor_map(p).distance_map(d));

    std::cout << "distances and parents:" << std::endl;
    graph_traits< graph_t >::vertex_iterator vi, vend;
    for (boost::tie(vi, vend) = vertices(g); vi != vend; ++vi)
    {
        std::cout << "distance(" << name[*vi] << ") = " << d[*vi] << ", ";
        std::cout << "parent(" << name[*vi] << ") = " << name[p[*vi]]
                  << std::endl;
    }
    std::cout << std::endl;

    std::ofstream dot_file("figs/dijkstra-eg.dot");
    dot_file << "digraph D {\n"
             << "  rankdir=LR\n"
             << "  size=\"4,3\"\n"
             << "  ratio=\"fill\"\n"
             << "  edge[style=\"bold\"]\n"
             << "  node[shape=\"circle\"]\n";

    graph_traits< graph_t >::edge_iterator ei, ei_end;
    for (boost::tie(ei, ei_end) = edges(g); ei != ei_end; ++ei)
    {
        graph_traits< graph_t >::edge_descriptor e = *ei;
        graph_traits< graph_t >::vertex_descriptor u = source(e, g),
                                                   v = target(e, g);
        dot_file << name[u] << " -> " << name[v] << "[label=\""
                 << get(weightmap, e) << "\"";
        if (p[v] == u)
            dot_file << ", color=\"black\"";
        else
            dot_file << ", color=\"grey\"";
        dot_file << "]";
    }
    dot_file << "}";
    return EXIT_SUCCESS;
}