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155 lines
5.6 KiB
155 lines
5.6 KiB
// |
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//======================================================================= |
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// Copyright 1997, 1998, 1999, 2000 University of Notre Dame. |
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// Authors: Andrew Lumsdaine, Lie-Quan Lee, Jeremy G. Siek |
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// |
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// Distributed under the Boost Software License, Version 1.0. (See |
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// accompanying file LICENSE_1_0.txt or copy at |
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// http://www.boost.org/LICENSE_1_0.txt) |
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//======================================================================= |
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// |
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#ifndef BOOST_GRAPH_MST_KRUSKAL_HPP |
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#define BOOST_GRAPH_MST_KRUSKAL_HPP |
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/* |
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*Minimum Spanning Tree |
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* Kruskal Algorithm |
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* |
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*Requirement: |
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* undirected graph |
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*/ |
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#include <vector> |
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#include <queue> |
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#include <functional> |
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#include <boost/property_map/property_map.hpp> |
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#include <boost/graph/graph_concepts.hpp> |
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#include <boost/graph/named_function_params.hpp> |
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#include <boost/pending/disjoint_sets.hpp> |
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#include <boost/pending/indirect_cmp.hpp> |
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namespace boost { |
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// Kruskal's algorithm for Minimum Spanning Tree |
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// |
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// This is a greedy algorithm to calculate the Minimum Spanning Tree |
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// for an undirected graph with weighted edges. The output will be a |
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// set of edges. |
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// |
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namespace detail { |
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template <class Graph, class OutputIterator, |
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class Rank, class Parent, class Weight> |
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void |
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kruskal_mst_impl(const Graph& G, |
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OutputIterator spanning_tree_edges, |
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Rank rank, Parent parent, Weight weight) |
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{ |
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if (num_vertices(G) == 0) return; // Nothing to do in this case |
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typedef typename graph_traits<Graph>::vertex_descriptor Vertex; |
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typedef typename graph_traits<Graph>::edge_descriptor Edge; |
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function_requires<VertexListGraphConcept<Graph> >(); |
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function_requires<EdgeListGraphConcept<Graph> >(); |
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function_requires<OutputIteratorConcept<OutputIterator, Edge> >(); |
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function_requires<ReadWritePropertyMapConcept<Rank, Vertex> >(); |
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function_requires<ReadWritePropertyMapConcept<Parent, Vertex> >(); |
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function_requires<ReadablePropertyMapConcept<Weight, Edge> >(); |
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typedef typename property_traits<Weight>::value_type W_value; |
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typedef typename property_traits<Rank>::value_type R_value; |
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typedef typename property_traits<Parent>::value_type P_value; |
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function_requires<ComparableConcept<W_value> >(); |
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function_requires<ConvertibleConcept<P_value, Vertex> >(); |
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function_requires<IntegerConcept<R_value> >(); |
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disjoint_sets<Rank, Parent> dset(rank, parent); |
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typename graph_traits<Graph>::vertex_iterator ui, uiend; |
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for (boost::tie(ui, uiend) = vertices(G); ui != uiend; ++ui) |
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dset.make_set(*ui); |
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typedef indirect_cmp<Weight, std::greater<W_value> > weight_greater; |
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weight_greater wl(weight); |
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std::priority_queue<Edge, std::vector<Edge>, weight_greater> Q(wl); |
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/*push all edge into Q*/ |
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typename graph_traits<Graph>::edge_iterator ei, eiend; |
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for (boost::tie(ei, eiend) = edges(G); ei != eiend; ++ei) |
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Q.push(*ei); |
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while (! Q.empty()) { |
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Edge e = Q.top(); |
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Q.pop(); |
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Vertex u = dset.find_set(source(e, G)); |
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Vertex v = dset.find_set(target(e, G)); |
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if ( u != v ) { |
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*spanning_tree_edges++ = e; |
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dset.link(u, v); |
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} |
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} |
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} |
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} // namespace detail |
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// Named Parameters Variants |
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template <class Graph, class OutputIterator> |
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inline void |
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kruskal_minimum_spanning_tree(const Graph& g, |
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OutputIterator spanning_tree_edges) |
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{ |
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typedef typename graph_traits<Graph>::vertices_size_type size_type; |
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typedef typename graph_traits<Graph>::vertex_descriptor vertex_t; |
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typedef typename property_map<Graph, vertex_index_t>::type index_map_t; |
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if (num_vertices(g) == 0) return; // Nothing to do in this case |
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typename graph_traits<Graph>::vertices_size_type |
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n = num_vertices(g); |
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std::vector<size_type> rank_map(n); |
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std::vector<vertex_t> pred_map(n); |
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detail::kruskal_mst_impl |
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(g, spanning_tree_edges, |
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make_iterator_property_map(rank_map.begin(), get(vertex_index, g), rank_map[0]), |
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make_iterator_property_map(pred_map.begin(), get(vertex_index, g), pred_map[0]), |
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get(edge_weight, g)); |
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} |
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template <class Graph, class OutputIterator, class P, class T, class R> |
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inline void |
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kruskal_minimum_spanning_tree(const Graph& g, |
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OutputIterator spanning_tree_edges, |
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const bgl_named_params<P, T, R>& params) |
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{ |
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typedef typename graph_traits<Graph>::vertices_size_type size_type; |
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typedef typename graph_traits<Graph>::vertex_descriptor vertex_t; |
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if (num_vertices(g) == 0) return; // Nothing to do in this case |
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typename graph_traits<Graph>::vertices_size_type n; |
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n = is_default_param(get_param(params, vertex_rank)) |
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? num_vertices(g) : 1; |
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std::vector<size_type> rank_map(n); |
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n = is_default_param(get_param(params, vertex_predecessor)) |
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? num_vertices(g) : 1; |
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std::vector<vertex_t> pred_map(n); |
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detail::kruskal_mst_impl |
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(g, spanning_tree_edges, |
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choose_param |
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(get_param(params, vertex_rank), |
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make_iterator_property_map |
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(rank_map.begin(), |
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choose_pmap(get_param(params, vertex_index), g, vertex_index), rank_map[0])), |
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choose_param |
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(get_param(params, vertex_predecessor), |
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make_iterator_property_map |
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(pred_map.begin(), |
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choose_const_pmap(get_param(params, vertex_index), g, vertex_index), |
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pred_map[0])), |
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choose_const_pmap(get_param(params, edge_weight), g, edge_weight)); |
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} |
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} // namespace boost |
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#endif // BOOST_GRAPH_MST_KRUSKAL_HPP |
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