Boost C++ Libraries

libs/graph/example/johnson-eg.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 <fstream>
#include <iostream>
#include <vector>
#include <iomanip>
#include <boost/property_map/property_map.hpp>
#include <boost/graph/adjacency_list.hpp>
#include <boost/graph/graphviz.hpp>
#include <boost/graph/johnson_all_pairs_shortest.hpp>

int main()
{
    using namespace boost;
    typedef adjacency_list< vecS, vecS, directedS, no_property,
        property< edge_weight_t, int, property< edge_weight2_t, int > > >
        Graph;
    const int V = 6;
    typedef std::pair< int, int > Edge;
    Edge edge_array[] = { Edge(0, 1), Edge(0, 2), Edge(0, 3), Edge(0, 4),
        Edge(0, 5), Edge(1, 2), Edge(1, 5), Edge(1, 3), Edge(2, 4), Edge(2, 5),
        Edge(3, 2), Edge(4, 3), Edge(4, 1), Edge(5, 4) };
    const std::size_t E = sizeof(edge_array) / sizeof(Edge);
#if defined(BOOST_MSVC) && BOOST_MSVC <= 1300
    // VC++ can't handle the iterator constructor
    Graph g(V);
    for (std::size_t j = 0; j < E; ++j)
        add_edge(edge_array[j].first, edge_array[j].second, g);
#else
    Graph g(edge_array, edge_array + E, V);
#endif

    property_map< Graph, edge_weight_t >::type w = get(edge_weight, g);
    int weights[] = { 0, 0, 0, 0, 0, 3, -4, 8, 1, 7, 4, -5, 2, 6 };
    int* wp = weights;

    graph_traits< Graph >::edge_iterator e, e_end;
    for (boost::tie(e, e_end) = edges(g); e != e_end; ++e)
        w[*e] = *wp++;

    std::vector< int > d(V, (std::numeric_limits< int >::max)());
    int D[V][V];
    johnson_all_pairs_shortest_paths(g, D, distance_map(&d[0]));

    std::cout << "       ";
    for (int k = 0; k < V; ++k)
        std::cout << std::setw(5) << k;
    std::cout << std::endl;
    for (int i = 0; i < V; ++i)
    {
        std::cout << std::setw(3) << i << " -> ";
        for (int j = 0; j < V; ++j)
        {
            if (D[i][j] == (std::numeric_limits< int >::max)())
                std::cout << std::setw(5) << "inf";
            else
                std::cout << std::setw(5) << D[i][j];
        }
        std::cout << std::endl;
    }

    std::ofstream fout("figs/johnson-eg.dot");
    fout << "digraph A {\n"
         << "  rankdir=LR\n"
         << "size=\"5,3\"\n"
         << "ratio=\"fill\"\n"
         << "edge[style=\"bold\"]\n"
         << "node[shape=\"circle\"]\n";

    graph_traits< Graph >::edge_iterator ei, ei_end;
    for (boost::tie(ei, ei_end) = edges(g); ei != ei_end; ++ei)
        fout << source(*ei, g) << " -> " << target(*ei, g)
             << "[label=" << get(edge_weight, g)[*ei] << "]\n";

    fout << "}\n";
    return 0;
}