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3rdparty/boost_1_81_0/libs/graph/example/bfs-example2.cpp 3.94 KB
977ed18d   Hu Chunming   提交三方库
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  //=======================================================================
  // 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/breadth_first_search.hpp>
  #include <boost/pending/indirect_cmp.hpp>
  #include <boost/range/irange.hpp>
  #include <boost/property_map/property_map.hpp>
  
  #include <iostream>
  
  using namespace boost;
  template < typename TimeMap >
  class bfs_time_visitor : public default_bfs_visitor
  {
      typedef typename property_traits< TimeMap >::value_type T;
  
  public:
      bfs_time_visitor(TimeMap tmap, T& t) : m_timemap(tmap), m_time(t) {}
      template < typename Vertex, typename Graph >
      void discover_vertex(Vertex u, const Graph& g) const
      {
          put(m_timemap, u, m_time++);
      }
      TimeMap m_timemap;
      T& m_time;
  };
  
  struct VertexProps
  {
      boost::default_color_type color;
      std::size_t discover_time;
      unsigned int index;
  };
  
  int main()
  {
      using namespace boost;
      // Select the graph type we wish to use
      typedef adjacency_list< listS, listS, undirectedS, VertexProps > graph_t;
      // Set up the vertex IDs and names
      enum
      {
          r,
          s,
          t,
          u,
          v,
          w,
          x,
          y,
          N
      };
      const char* name = "rstuvwxy";
      // Specify the edges in the graph
      typedef std::pair< int, int > E;
      E edge_array[] = { E(r, s), E(r, v), E(s, w), E(w, r), E(w, t), E(w, x),
          E(x, t), E(t, u), E(x, y), E(u, y) };
      // Create the graph object
      const int n_edges = sizeof(edge_array) / sizeof(E);
  #if defined(BOOST_MSVC) && BOOST_MSVC <= 1300
      // VC++ has trouble with the edge iterator constructor
      graph_t g;
      std::vector< graph_traits< graph_t >::vertex_descriptor > verts;
      for (std::size_t i = 0; i < N; ++i)
          verts.push_back(add_vertex(g));
      for (std::size_t j = 0; j < n_edges; ++j)
          add_edge(verts[edge_array[j].first], verts[edge_array[j].second], g);
  #else
      typedef graph_traits< graph_t >::vertices_size_type v_size_t;
      graph_t g(edge_array, edge_array + n_edges, v_size_t(N));
  #endif
  
      // Typedefs
      typedef graph_traits< graph_t >::vertices_size_type Size;
  
      Size time = 0;
      typedef property_map< graph_t, std::size_t VertexProps::* >::type
          dtime_map_t;
      dtime_map_t dtime_map = get(&VertexProps::discover_time, g);
      bfs_time_visitor< dtime_map_t > vis(dtime_map, time);
      breadth_first_search(
          g, vertex(s, g), color_map(get(&VertexProps::color, g)).visitor(vis));
  
      // a vector to hold the discover time property for each vertex
      std::vector< Size > dtime(num_vertices(g));
      typedef iterator_property_map< std::vector< Size >::iterator,
          property_map< graph_t, unsigned int VertexProps::* >::type >
          dtime_pm_type;
      graph_traits< graph_t >::vertex_iterator vi, vi_end;
      std::size_t c = 0;
      for (boost::tie(vi, vi_end) = vertices(g); vi != vi_end; ++vi, ++c)
      {
          dtime[c] = dtime_map[*vi];
          put(&VertexProps::index, g, *vi, c);
      }
      dtime_pm_type dtime_pm(dtime.begin(), get(&VertexProps::index, g));
  
      // Use std::sort to order the vertices by their discover time
      std::vector< graph_traits< graph_t >::vertices_size_type > discover_order(
          N);
      integer_range< int > range(0, N);
      std::copy(range.begin(), range.end(), discover_order.begin());
      std::sort(discover_order.begin(), discover_order.end(),
          make_indirect_cmp(std::less< Size >(),
              make_iterator_property_map(
                  dtime.begin(), typed_identity_property_map< std::size_t >())));
  
      std::cout << "order of discovery: ";
      for (int i = 0; i < N; ++i)
          std::cout << name[discover_order[i]] << " ";
      std::cout << std::endl;
  
      return EXIT_SUCCESS;
  }