Boost C++ Libraries

libs/graph/example/dag_shortest_paths.cpp

//=======================================================================
// Copyright 1997, 1998, 1999, 2000 University of Notre Dame.
// Authors: Andrew Lumsdaine, Lie-Quan Lee, Jeremy G. Siek
//
// 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/graph/dag_shortest_paths.hpp>
#include <boost/graph/adjacency_list.hpp>

#include <iostream>

// Example from Introduction to Algorithms by Cormen, et all p.537.

// Sample output:
//  r: inifinity
//  s: 0
//  t: 2
//  u: 6
//  v: 5
//  x: 3

int main()
{
    using namespace boost;
    typedef adjacency_list< vecS, vecS, directedS,
        property< vertex_distance_t, int >, property< edge_weight_t, int > >
        graph_t;
    graph_t g(6);
    enum verts
    {
        r,
        s,
        t,
        u,
        v,
        x
    };
    char name[] = "rstuvx";
    add_edge(r, s, 5, g);
    add_edge(r, t, 3, g);
    add_edge(s, t, 2, g);
    add_edge(s, u, 6, g);
    add_edge(t, u, 7, g);
    add_edge(t, v, 4, g);
    add_edge(t, x, 2, g);
    add_edge(u, v, -1, g);
    add_edge(u, x, 1, g);
    add_edge(v, x, -2, g);

    property_map< graph_t, vertex_distance_t >::type d_map
        = get(vertex_distance, g);

#if defined(BOOST_MSVC) && BOOST_MSVC <= 1300
    // VC++ has trouble with the named-parameter mechanism, so
    // we make a direct call to the underlying implementation function.
    std::vector< default_color_type > color(num_vertices(g));
    std::vector< std::size_t > pred(num_vertices(g));
    default_dijkstra_visitor vis;
    std::less< int > compare;
    closed_plus< int > combine;
    property_map< graph_t, edge_weight_t >::type w_map = get(edge_weight, g);
    dag_shortest_paths(g, s, d_map, w_map, &color[0], &pred[0], vis, compare,
        combine, (std::numeric_limits< int >::max)(), 0);
#else
    dag_shortest_paths(g, s, distance_map(d_map));
#endif

    graph_traits< graph_t >::vertex_iterator vi, vi_end;
    for (boost::tie(vi, vi_end) = vertices(g); vi != vi_end; ++vi)
        if (d_map[*vi] == (std::numeric_limits< int >::max)())
            std::cout << name[*vi] << ": inifinity\n";
        else
            std::cout << name[*vi] << ": " << d_map[*vi] << '\n';
    return 0;
}