| // |
| //======================================================================= |
| // 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) |
| //======================================================================= |
| // |
| #ifndef BOOST_GRAPH_MST_KRUSKAL_HPP |
| #define BOOST_GRAPH_MST_KRUSKAL_HPP |
| |
| /* |
| *Minimum Spanning Tree |
| * Kruskal Algorithm |
| * |
| *Requirement: |
| * undirected graph |
| */ |
| |
| #include <vector> |
| #include <queue> |
| #include <functional> |
| |
| #include <boost/property_map/property_map.hpp> |
| #include <boost/graph/graph_concepts.hpp> |
| #include <boost/graph/named_function_params.hpp> |
| #include <boost/pending/disjoint_sets.hpp> |
| #include <boost/pending/indirect_cmp.hpp> |
| |
| |
| namespace boost { |
| |
| // Kruskal's algorithm for Minimum Spanning Tree |
| // |
| // This is a greedy algorithm to calculate the Minimum Spanning Tree |
| // for an undirected graph with weighted edges. The output will be a |
| // set of edges. |
| // |
| |
| namespace detail { |
| |
| template <class Graph, class OutputIterator, |
| class Rank, class Parent, class Weight> |
| void |
| kruskal_mst_impl(const Graph& G, |
| OutputIterator spanning_tree_edges, |
| Rank rank, Parent parent, Weight weight) |
| { |
| if (num_vertices(G) == 0) return; // Nothing to do in this case |
| typedef typename graph_traits<Graph>::vertex_descriptor Vertex; |
| typedef typename graph_traits<Graph>::edge_descriptor Edge; |
| function_requires<VertexListGraphConcept<Graph> >(); |
| function_requires<EdgeListGraphConcept<Graph> >(); |
| function_requires<OutputIteratorConcept<OutputIterator, Edge> >(); |
| function_requires<ReadWritePropertyMapConcept<Rank, Vertex> >(); |
| function_requires<ReadWritePropertyMapConcept<Parent, Vertex> >(); |
| function_requires<ReadablePropertyMapConcept<Weight, Edge> >(); |
| typedef typename property_traits<Weight>::value_type W_value; |
| typedef typename property_traits<Rank>::value_type R_value; |
| typedef typename property_traits<Parent>::value_type P_value; |
| function_requires<ComparableConcept<W_value> >(); |
| function_requires<ConvertibleConcept<P_value, Vertex> >(); |
| function_requires<IntegerConcept<R_value> >(); |
| |
| disjoint_sets<Rank, Parent> dset(rank, parent); |
| |
| typename graph_traits<Graph>::vertex_iterator ui, uiend; |
| for (boost::tie(ui, uiend) = vertices(G); ui != uiend; ++ui) |
| dset.make_set(*ui); |
| |
| typedef indirect_cmp<Weight, std::greater<W_value> > weight_greater; |
| weight_greater wl(weight); |
| std::priority_queue<Edge, std::vector<Edge>, weight_greater> Q(wl); |
| /*push all edge into Q*/ |
| typename graph_traits<Graph>::edge_iterator ei, eiend; |
| for (boost::tie(ei, eiend) = edges(G); ei != eiend; ++ei) |
| Q.push(*ei); |
| |
| while (! Q.empty()) { |
| Edge e = Q.top(); |
| Q.pop(); |
| Vertex u = dset.find_set(source(e, G)); |
| Vertex v = dset.find_set(target(e, G)); |
| if ( u != v ) { |
| *spanning_tree_edges++ = e; |
| dset.link(u, v); |
| } |
| } |
| } |
| |
| } // namespace detail |
| |
| // Named Parameters Variants |
| |
| template <class Graph, class OutputIterator> |
| inline void |
| kruskal_minimum_spanning_tree(const Graph& g, |
| OutputIterator spanning_tree_edges) |
| { |
| typedef typename graph_traits<Graph>::vertices_size_type size_type; |
| typedef typename graph_traits<Graph>::vertex_descriptor vertex_t; |
| typedef typename property_map<Graph, vertex_index_t>::type index_map_t; |
| if (num_vertices(g) == 0) return; // Nothing to do in this case |
| typename graph_traits<Graph>::vertices_size_type |
| n = num_vertices(g); |
| std::vector<size_type> rank_map(n); |
| std::vector<vertex_t> pred_map(n); |
| |
| detail::kruskal_mst_impl |
| (g, spanning_tree_edges, |
| make_iterator_property_map(rank_map.begin(), get(vertex_index, g), rank_map[0]), |
| make_iterator_property_map(pred_map.begin(), get(vertex_index, g), pred_map[0]), |
| get(edge_weight, g)); |
| } |
| |
| template <class Graph, class OutputIterator, class P, class T, class R> |
| inline void |
| kruskal_minimum_spanning_tree(const Graph& g, |
| OutputIterator spanning_tree_edges, |
| const bgl_named_params<P, T, R>& params) |
| { |
| typedef typename graph_traits<Graph>::vertices_size_type size_type; |
| typedef typename graph_traits<Graph>::vertex_descriptor vertex_t; |
| if (num_vertices(g) == 0) return; // Nothing to do in this case |
| typename graph_traits<Graph>::vertices_size_type n; |
| n = is_default_param(get_param(params, vertex_rank)) |
| ? num_vertices(g) : 1; |
| std::vector<size_type> rank_map(n); |
| n = is_default_param(get_param(params, vertex_predecessor)) |
| ? num_vertices(g) : 1; |
| std::vector<vertex_t> pred_map(n); |
| |
| detail::kruskal_mst_impl |
| (g, spanning_tree_edges, |
| choose_param |
| (get_param(params, vertex_rank), |
| make_iterator_property_map |
| (rank_map.begin(), |
| choose_pmap(get_param(params, vertex_index), g, vertex_index), rank_map[0])), |
| choose_param |
| (get_param(params, vertex_predecessor), |
| make_iterator_property_map |
| (pred_map.begin(), |
| choose_const_pmap(get_param(params, vertex_index), g, vertex_index), |
| pred_map[0])), |
| choose_const_pmap(get_param(params, edge_weight), g, edge_weight)); |
| } |
| |
| } // namespace boost |
| |
| |
| #endif // BOOST_GRAPH_MST_KRUSKAL_HPP |
| |