[857] | 1 | //
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| 2 | //=======================================================================
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| 3 | // Copyright 1997, 1998, 1999, 2000 University of Notre Dame.
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| 4 | // Authors: Andrew Lumsdaine, Lie-Quan Lee, Jeremy G. Siek
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| 5 | //
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| 6 | // Distributed under the Boost Software License, Version 1.0. (See
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| 7 | // accompanying file LICENSE_1_0.txt or copy at
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| 8 | // http://www.boost.org/LICENSE_1_0.txt)
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| 9 | //=======================================================================
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| 10 | //
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| 11 | #ifndef BOOST_GRAPH_MST_KRUSKAL_HPP
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| 12 | #define BOOST_GRAPH_MST_KRUSKAL_HPP
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| 13 |
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| 14 | /*
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| 15 | *Minimum Spanning Tree
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| 16 | * Kruskal Algorithm
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| 17 | *
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| 18 | *Requirement:
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| 19 | * undirected graph
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| 20 | */
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| 21 |
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| 22 | #include <vector>
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| 23 | #include <queue>
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| 24 | #include <functional>
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| 25 |
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| 26 | #include <boost/property_map.hpp>
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| 27 | #include <boost/graph/graph_concepts.hpp>
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| 28 | #include <boost/graph/named_function_params.hpp>
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| 29 | #include <boost/pending/disjoint_sets.hpp>
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| 30 | #include <boost/pending/indirect_cmp.hpp>
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| 31 |
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| 32 |
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| 33 | namespace boost {
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| 34 |
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| 35 | // Kruskal's algorithm for Minimum Spanning Tree
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| 36 | //
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| 37 | // This is a greedy algorithm to calculate the Minimum Spanning Tree
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| 38 | // for an undirected graph with weighted edges. The output will be a
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| 39 | // set of edges.
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| 40 | //
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| 41 |
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| 42 | namespace detail {
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| 43 |
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| 44 | template <class Graph, class OutputIterator,
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| 45 | class Rank, class Parent, class Weight>
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| 46 | void
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| 47 | kruskal_mst_impl(const Graph& G,
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| 48 | OutputIterator spanning_tree_edges,
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| 49 | Rank rank, Parent parent, Weight weight)
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| 50 | {
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| 51 | typedef typename graph_traits<Graph>::vertex_descriptor Vertex;
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| 52 | typedef typename graph_traits<Graph>::edge_descriptor Edge;
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| 53 | function_requires<VertexListGraphConcept<Graph> >();
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| 54 | function_requires<EdgeListGraphConcept<Graph> >();
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| 55 | function_requires<OutputIteratorConcept<OutputIterator, Edge> >();
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| 56 | function_requires<ReadWritePropertyMapConcept<Rank, Vertex> >();
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| 57 | function_requires<ReadWritePropertyMapConcept<Parent, Vertex> >();
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| 58 | function_requires<ReadablePropertyMapConcept<Weight, Edge> >();
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| 59 | typedef typename property_traits<Weight>::value_type W_value;
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| 60 | typedef typename property_traits<Rank>::value_type R_value;
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| 61 | typedef typename property_traits<Parent>::value_type P_value;
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| 62 | function_requires<ComparableConcept<W_value> >();
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| 63 | function_requires<ConvertibleConcept<P_value, Vertex> >();
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| 64 | function_requires<IntegerConcept<R_value> >();
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| 65 |
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| 66 | disjoint_sets<Rank, Parent> dset(rank, parent);
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| 67 |
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| 68 | typename graph_traits<Graph>::vertex_iterator ui, uiend;
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| 69 | for (boost::tie(ui, uiend) = vertices(G); ui != uiend; ++ui)
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| 70 | dset.make_set(*ui);
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| 71 |
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| 72 | typedef indirect_cmp<Weight, std::greater<W_value> > weight_greater;
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| 73 | weight_greater wl(weight);
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| 74 | std::priority_queue<Edge, std::vector<Edge>, weight_greater> Q(wl);
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| 75 | /*push all edge into Q*/
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| 76 | typename graph_traits<Graph>::edge_iterator ei, eiend;
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| 77 | for (boost::tie(ei, eiend) = edges(G); ei != eiend; ++ei)
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| 78 | Q.push(*ei);
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| 79 |
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| 80 | while (! Q.empty()) {
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| 81 | Edge e = Q.top();
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| 82 | Q.pop();
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| 83 | Vertex u = dset.find_set(source(e, G));
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| 84 | Vertex v = dset.find_set(target(e, G));
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| 85 | if ( u != v ) {
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| 86 | *spanning_tree_edges++ = e;
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| 87 | dset.link(u, v);
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| 88 | }
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| 89 | }
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| 90 | }
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| 91 |
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| 92 | } // namespace detail
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| 93 |
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| 94 | // Named Parameters Variants
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| 95 |
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| 96 | template <class Graph, class OutputIterator>
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| 97 | inline void
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| 98 | kruskal_minimum_spanning_tree(const Graph& g,
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| 99 | OutputIterator spanning_tree_edges)
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| 100 | {
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| 101 | typedef typename graph_traits<Graph>::vertices_size_type size_type;
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| 102 | typedef typename graph_traits<Graph>::vertex_descriptor vertex_t;
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| 103 | typedef typename property_map<Graph, vertex_index_t>::type index_map_t;
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| 104 | typename graph_traits<Graph>::vertices_size_type
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| 105 | n = num_vertices(g);
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| 106 | std::vector<size_type> rank_map(n);
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| 107 | std::vector<vertex_t> pred_map(n);
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| 108 |
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| 109 | detail::kruskal_mst_impl
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| 110 | (g, spanning_tree_edges,
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| 111 | make_iterator_property_map(rank_map.begin(), get(vertex_index, g), rank_map[0]),
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| 112 | make_iterator_property_map(pred_map.begin(), get(vertex_index, g), pred_map[0]),
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| 113 | get(edge_weight, g));
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| 114 | }
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| 115 |
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| 116 | template <class Graph, class OutputIterator, class P, class T, class R>
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| 117 | inline void
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| 118 | kruskal_minimum_spanning_tree(const Graph& g,
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| 119 | OutputIterator spanning_tree_edges,
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| 120 | const bgl_named_params<P, T, R>& params)
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| 121 | {
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| 122 | typedef typename graph_traits<Graph>::vertices_size_type size_type;
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| 123 | typedef typename graph_traits<Graph>::vertex_descriptor vertex_t;
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| 124 | typename graph_traits<Graph>::vertices_size_type n;
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| 125 | n = is_default_param(get_param(params, vertex_rank))
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| 126 | ? num_vertices(g) : 1;
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| 127 | std::vector<size_type> rank_map(n);
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| 128 | n = is_default_param(get_param(params, vertex_predecessor))
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| 129 | ? num_vertices(g) : 1;
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| 130 | std::vector<vertex_t> pred_map(n);
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| 131 |
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| 132 | detail::kruskal_mst_impl
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| 133 | (g, spanning_tree_edges,
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| 134 | choose_param
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| 135 | (get_param(params, vertex_rank),
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| 136 | make_iterator_property_map
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| 137 | (rank_map.begin(),
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| 138 | choose_pmap(get_param(params, vertex_index), g, vertex_index), rank_map[0])),
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| 139 | choose_param
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| 140 | (get_param(params, vertex_predecessor),
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| 141 | make_iterator_property_map
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| 142 | (pred_map.begin(),
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| 143 | choose_const_pmap(get_param(params, vertex_index), g, vertex_index),
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| 144 | pred_map[0])),
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| 145 | choose_const_pmap(get_param(params, edge_weight), g, edge_weight));
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| 146 | }
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| 147 |
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| 148 | } // namespace boost
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| 149 |
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| 150 |
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| 151 | #endif // BOOST_GRAPH_MST_KRUSKAL_HPP
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| 152 |
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