Source of kevin-bacon.cpp


  1: //=======================================================================
  2: // Copyright 2001 Jeremy G. Siek, Andrew Lumsdaine, Lie-Quan Lee,
  3: //
  4: // Distributed under the Boost Software License, Version 1.0. (See
  5: // accompanying file LICENSE_1_0.txt or copy at
  6: // http://www.boost.org/LICENSE_1_0.txt)
  7: //=======================================================================
  8: #include <boost/config.hpp>
  9: #include <iostream>
 10: #include <fstream>
 11: #include <string>
 12: #include <boost/tokenizer.hpp>
 13: #include <boost/tuple/tuple.hpp>
 14: #include <boost/graph/adjacency_list.hpp>
 15: #include <boost/graph/visitors.hpp>
 16: #include <boost/graph/breadth_first_search.hpp>
 17: #include <map>

 19: using namespace boost;

 21: template <typename DistanceMap>
 22: class bacon_number_recorder : public default_bfs_visitor
 23: {
 24: public:
 25:   bacon_number_recorder(DistanceMap dist) : d(dist) { }

 27:   template <typename Edge, typename Graph>
 28:   void tree_edge(Edge e, const Graph& g) const
 29:   {
 30:     typename graph_traits<Graph>::vertex_descriptor
 31:       u = source(e, g), v = target(e, g);
 32:       d[v] = d[u] + 1;
 33:   }
 34: private:
 35:     DistanceMap d;
 36: };

 38: // Convenience function
 39: template < typename DistanceMap >
 40: bacon_number_recorder<DistanceMap>
 41: record_bacon_number(DistanceMap d)
 42: {
 43:   return bacon_number_recorder < DistanceMap > (d);
 44: }


 47: int
 48: main()
 49: {
 50:   std::ifstream datafile("./kevin-bacon.dat");
 51:   if (!datafile) {
 52:     std::cerr << "No ./kevin-bacon.dat file" << std::endl;
 53:     return EXIT_FAILURE;
 54:   }

 56:   typedef adjacency_list < vecS, vecS, undirectedS, property < vertex_name_t,
 57:     std::string >, property < edge_name_t, std::string > > Graph;
 58:   Graph g;

 60:   typedef property_map < Graph, vertex_name_t >::type actor_name_map_t;
 61:   actor_name_map_t actor_name = get(vertex_name, g);
 62:   typedef property_map < Graph, edge_name_t >::type movie_name_map_t;
 63:   movie_name_map_t connecting_movie = get(edge_name, g);

 65:   typedef graph_traits < Graph >::vertex_descriptor Vertex;
 66:   typedef std::map < std::string, Vertex > NameVertexMap;
 67:   NameVertexMap actors;

 69:   for (std::string line; std::getline(datafile, line);) {
 70:     char_delimiters_separator < char >sep(false, "", ";");
 71:     tokenizer <> line_toks(line, sep);
 72:     tokenizer <>::iterator i = line_toks.begin();
 73:     std::string actors_name = *i++;
 74:     NameVertexMap::iterator pos;
 75:     bool inserted;
 76:     Vertex u, v;
 77:     tie(pos, inserted) = actors.insert(std::make_pair(actors_name, Vertex()));
 78:     if (inserted) {
 79:       u = add_vertex(g);
 80:       actor_name[u] = actors_name;
 81:       pos->second = u;
 82:     } else
 83:       u = pos->second;

 85:     std::string movie_name = *i++;

 87:     tie(pos, inserted) = actors.insert(std::make_pair(*i, Vertex()));
 88:     if (inserted) {
 89:       v = add_vertex(g);
 90:       actor_name[v] = *i;
 91:       pos->second = v;
 92:     } else
 93:       v = pos->second;

 95:     graph_traits < Graph >::edge_descriptor e;
 96:     tie(e, inserted) = add_edge(u, v, g);
 97:     if (inserted)
 98:       connecting_movie[e] = movie_name;

100:   }

102:   std::vector < int >bacon_number(num_vertices(g));

104:   Vertex src = actors["Kevin Bacon"];
105:   bacon_number[src] = 0;

107:   breadth_first_search(g, src,
108:                        visitor(record_bacon_number(&bacon_number[0])));

110:   graph_traits < Graph >::vertex_iterator i, end;
111:   for (tie(i, end) = vertices(g); i != end; ++i) {
112:     std::cout << actor_name[*i] << " has a Bacon number of "
113:       << bacon_number[*i] << std::endl;
114:   }

116:   return 0;
117: }