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3rdparty/boost_1_81_0/libs/graph/example/kruskal-example.cpp 2.77 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/kruskal_min_spanning_tree.hpp>
  #include <iostream>
  #include <fstream>
  
  int main()
  {
      using namespace boost;
      typedef adjacency_list< vecS, vecS, undirectedS, no_property,
          property< edge_weight_t, int > >
          Graph;
      typedef graph_traits< Graph >::edge_descriptor Edge;
      typedef std::pair< int, int > E;
  
      const int num_nodes = 5;
      E edge_array[] = { E(0, 2), E(1, 3), E(1, 4), E(2, 1), E(2, 3), E(3, 4),
          E(4, 0), E(4, 1) };
      int weights[] = { 1, 1, 2, 7, 3, 1, 1, 1 };
      std::size_t num_edges = sizeof(edge_array) / sizeof(E);
  #if defined(BOOST_MSVC) && BOOST_MSVC <= 1300
      Graph g(num_nodes);
      property_map< Graph, edge_weight_t >::type weightmap = get(edge_weight, g);
      for (std::size_t j = 0; j < num_edges; ++j)
      {
          Edge e;
          bool inserted;
          boost::tie(e, inserted)
              = add_edge(edge_array[j].first, edge_array[j].second, g);
          weightmap[e] = weights[j];
      }
  #else
      Graph g(edge_array, edge_array + num_edges, weights, num_nodes);
  #endif
      property_map< Graph, edge_weight_t >::type weight = get(edge_weight, g);
      std::vector< Edge > spanning_tree;
  
      kruskal_minimum_spanning_tree(g, std::back_inserter(spanning_tree));
  
      std::cout << "Print the edges in the MST:" << std::endl;
      for (std::vector< Edge >::iterator ei = spanning_tree.begin();
           ei != spanning_tree.end(); ++ei)
      {
          std::cout << source(*ei, g) << " <--> " << target(*ei, g)
                    << " with weight of " << weight[*ei] << std::endl;
      }
  
      std::ofstream fout("figs/kruskal-eg.dot");
      fout << "graph A {\n"
           << " rankdir=LR\n"
           << " size=\"3,3\"\n"
           << " ratio=\"filled\"\n"
           << " edge[style=\"bold\"]\n"
           << " node[shape=\"circle\"]\n";
      graph_traits< Graph >::edge_iterator eiter, eiter_end;
      for (boost::tie(eiter, eiter_end) = edges(g); eiter != eiter_end; ++eiter)
      {
          fout << source(*eiter, g) << " -- " << target(*eiter, g);
          if (std::find(spanning_tree.begin(), spanning_tree.end(), *eiter)
              != spanning_tree.end())
              fout << "[color=\"black\", label=\"" << get(edge_weight, g, *eiter)
                   << "\"];\n";
          else
              fout << "[color=\"gray\", label=\"" << get(edge_weight, g, *eiter)
                   << "\"];\n";
      }
      fout << "}\n";
      return EXIT_SUCCESS;
  }