Boost C++ Libraries

libs/graph/example/dfs-example.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/graph/adjacency_list.hpp>
#include <boost/graph/depth_first_search.hpp>
#include <boost/range/irange.hpp>
#include <boost/pending/indirect_cmp.hpp>

#include <iostream>

using namespace boost;
template < typename TimeMap >
class dfs_time_visitor : public default_dfs_visitor
{
    typedef typename property_traits< TimeMap >::value_type T;

public:
    dfs_time_visitor(TimeMap dmap, TimeMap fmap, T& t)
    : m_dtimemap(dmap), m_ftimemap(fmap), m_time(t)
    {
    }
    template < typename Vertex, typename Graph >
    void discover_vertex(Vertex u, const Graph& g) const
    {
        put(m_dtimemap, u, m_time++);
    }
    template < typename Vertex, typename Graph >
    void finish_vertex(Vertex u, const Graph& g) const
    {
        put(m_ftimemap, u, m_time++);
    }
    TimeMap m_dtimemap;
    TimeMap m_ftimemap;
    T& m_time;
};

int main()
{
    // Select the graph type we wish to use
    typedef adjacency_list< vecS, vecS, directedS > graph_t;
    typedef graph_traits< graph_t >::vertices_size_type size_type;
    // Set up the vertex names
    enum
    {
        u,
        v,
        w,
        x,
        y,
        z,
        N
    };
    char name[] = { 'u', 'v', 'w', 'x', 'y', 'z' };
    // Specify the edges in the graph
    typedef std::pair< int, int > E;
    E edge_array[] = { E(u, v), E(u, x), E(x, v), E(y, x), E(v, y), E(w, y),
        E(w, z), E(z, z) };
#if defined(BOOST_MSVC) && BOOST_MSVC <= 1300
    graph_t g(N);
    for (std::size_t j = 0; j < sizeof(edge_array) / sizeof(E); ++j)
        add_edge(edge_array[j].first, edge_array[j].second, g);
#else
    graph_t g(edge_array, edge_array + sizeof(edge_array) / sizeof(E), N);
#endif

    // discover time and finish time properties
    std::vector< size_type > dtime(num_vertices(g));
    std::vector< size_type > ftime(num_vertices(g));
    typedef iterator_property_map< std::vector< size_type >::iterator,
        property_map< graph_t, vertex_index_t >::const_type >
        time_pm_type;
    time_pm_type dtime_pm(dtime.begin(), get(vertex_index, g));
    time_pm_type ftime_pm(ftime.begin(), get(vertex_index, g));
    size_type t = 0;
    dfs_time_visitor< time_pm_type > vis(dtime_pm, ftime_pm, t);

    depth_first_search(g, visitor(vis));

    // use std::sort to order the vertices by their discover time
    std::vector< size_type > discover_order(N);
    integer_range< size_type > r(0, N);
    std::copy(r.begin(), r.end(), discover_order.begin());
    std::sort(discover_order.begin(), discover_order.end(),
        indirect_cmp< time_pm_type, std::less< size_type > >(dtime_pm));
    std::cout << "order of discovery: ";
    int i;
    for (i = 0; i < N; ++i)
        std::cout << name[discover_order[i]] << " ";

    std::vector< size_type > finish_order(N);
    std::copy(r.begin(), r.end(), finish_order.begin());
    std::sort(finish_order.begin(), finish_order.end(),
        indirect_cmp< time_pm_type, std::less< size_type > >(ftime_pm));
    std::cout << std::endl << "order of finish: ";
    for (i = 0; i < N; ++i)
        std::cout << name[finish_order[i]] << " ";
    std::cout << std::endl;

    return EXIT_SUCCESS;
}