[209] | 1 | /* -*- mode: C++; indent-tabs-mode: nil; -*- |
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[100] | 2 | * |
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[209] | 3 | * This file is a part of LEMON, a generic C++ optimization library. |
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[100] | 4 | * |
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| 5 | * Copyright (C) 2003-2008 |
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| 6 | * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport |
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| 7 | * (Egervary Research Group on Combinatorial Optimization, EGRES). |
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| 8 | * |
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| 9 | * Permission to use, modify and distribute this software is granted |
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| 10 | * provided that this copyright notice appears in all copies. For |
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| 11 | * precise terms see the accompanying LICENSE file. |
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| 12 | * |
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| 13 | * This software is provided "AS IS" with no warranty of any kind, |
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| 14 | * express or implied, and with no claim as to its suitability for any |
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| 15 | * purpose. |
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| 16 | * |
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| 17 | */ |
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| 18 | |
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| 19 | #ifndef LEMON_BFS_H |
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| 20 | #define LEMON_BFS_H |
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| 21 | |
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| 22 | ///\ingroup search |
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| 23 | ///\file |
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[244] | 24 | ///\brief BFS algorithm. |
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[100] | 25 | |
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| 26 | #include <lemon/list_graph.h> |
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| 27 | #include <lemon/bits/path_dump.h> |
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[220] | 28 | #include <lemon/core.h> |
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[100] | 29 | #include <lemon/error.h> |
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| 30 | #include <lemon/maps.h> |
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[278] | 31 | #include <lemon/path.h> |
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[100] | 32 | |
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| 33 | namespace lemon { |
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| 34 | |
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| 35 | ///Default traits class of Bfs class. |
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| 36 | |
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| 37 | ///Default traits class of Bfs class. |
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[157] | 38 | ///\tparam GR Digraph type. |
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[100] | 39 | template<class GR> |
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| 40 | struct BfsDefaultTraits |
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| 41 | { |
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[244] | 42 | ///The type of the digraph the algorithm runs on. |
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[100] | 43 | typedef GR Digraph; |
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[244] | 44 | |
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| 45 | ///\brief The type of the map that stores the predecessor |
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[100] | 46 | ///arcs of the shortest paths. |
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[209] | 47 | /// |
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[244] | 48 | ///The type of the map that stores the predecessor |
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[100] | 49 | ///arcs of the shortest paths. |
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| 50 | ///It must meet the \ref concepts::WriteMap "WriteMap" concept. |
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[244] | 51 | typedef typename Digraph::template NodeMap<typename Digraph::Arc> PredMap; |
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[301] | 52 | ///Instantiates a PredMap. |
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[209] | 53 | |
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[329] | 54 | ///This function instantiates a PredMap. |
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[244] | 55 | ///\param g is the digraph, to which we would like to define the |
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[301] | 56 | ///PredMap. |
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[244] | 57 | static PredMap *createPredMap(const Digraph &g) |
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[100] | 58 | { |
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[244] | 59 | return new PredMap(g); |
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[100] | 60 | } |
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[244] | 61 | |
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[100] | 62 | ///The type of the map that indicates which nodes are processed. |
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[209] | 63 | |
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[100] | 64 | ///The type of the map that indicates which nodes are processed. |
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| 65 | ///It must meet the \ref concepts::WriteMap "WriteMap" concept. |
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| 66 | typedef NullMap<typename Digraph::Node,bool> ProcessedMap; |
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[301] | 67 | ///Instantiates a ProcessedMap. |
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[209] | 68 | |
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[301] | 69 | ///This function instantiates a ProcessedMap. |
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[100] | 70 | ///\param g is the digraph, to which |
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[301] | 71 | ///we would like to define the ProcessedMap |
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[100] | 72 | #ifdef DOXYGEN |
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[244] | 73 | static ProcessedMap *createProcessedMap(const Digraph &g) |
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[100] | 74 | #else |
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[244] | 75 | static ProcessedMap *createProcessedMap(const Digraph &) |
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[100] | 76 | #endif |
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| 77 | { |
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| 78 | return new ProcessedMap(); |
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| 79 | } |
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[244] | 80 | |
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[100] | 81 | ///The type of the map that indicates which nodes are reached. |
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[209] | 82 | |
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[329] | 83 | ///The type of the map that indicates which nodes are reached.///It must meet the \ref concepts::ReadWriteMap "ReadWriteMap" concept. |
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[100] | 84 | typedef typename Digraph::template NodeMap<bool> ReachedMap; |
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[301] | 85 | ///Instantiates a ReachedMap. |
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[209] | 86 | |
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[301] | 87 | ///This function instantiates a ReachedMap. |
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[244] | 88 | ///\param g is the digraph, to which |
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[301] | 89 | ///we would like to define the ReachedMap. |
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[244] | 90 | static ReachedMap *createReachedMap(const Digraph &g) |
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[100] | 91 | { |
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[244] | 92 | return new ReachedMap(g); |
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[100] | 93 | } |
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[209] | 94 | |
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[244] | 95 | ///The type of the map that stores the distances of the nodes. |
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| 96 | |
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| 97 | ///The type of the map that stores the distances of the nodes. |
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[100] | 98 | ///It must meet the \ref concepts::WriteMap "WriteMap" concept. |
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| 99 | typedef typename Digraph::template NodeMap<int> DistMap; |
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[301] | 100 | ///Instantiates a DistMap. |
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[209] | 101 | |
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[301] | 102 | ///This function instantiates a DistMap. |
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[244] | 103 | ///\param g is the digraph, to which we would like to define the |
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[301] | 104 | ///DistMap. |
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[244] | 105 | static DistMap *createDistMap(const Digraph &g) |
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[100] | 106 | { |
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[244] | 107 | return new DistMap(g); |
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[100] | 108 | } |
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| 109 | }; |
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[209] | 110 | |
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[100] | 111 | ///%BFS algorithm class. |
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[209] | 112 | |
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[100] | 113 | ///\ingroup search |
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| 114 | ///This class provides an efficient implementation of the %BFS algorithm. |
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| 115 | /// |
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[278] | 116 | ///There is also a \ref bfs() "function-type interface" for the BFS |
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[244] | 117 | ///algorithm, which is convenient in the simplier cases and it can be |
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| 118 | ///used easier. |
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| 119 | /// |
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| 120 | ///\tparam GR The type of the digraph the algorithm runs on. |
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| 121 | ///The default value is \ref ListDigraph. The value of GR is not used |
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| 122 | ///directly by \ref Bfs, it is only passed to \ref BfsDefaultTraits. |
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[157] | 123 | ///\tparam TR Traits class to set various data types used by the algorithm. |
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[100] | 124 | ///The default traits class is |
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| 125 | ///\ref BfsDefaultTraits "BfsDefaultTraits<GR>". |
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| 126 | ///See \ref BfsDefaultTraits for the documentation of |
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| 127 | ///a Bfs traits class. |
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| 128 | #ifdef DOXYGEN |
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| 129 | template <typename GR, |
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[209] | 130 | typename TR> |
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[100] | 131 | #else |
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| 132 | template <typename GR=ListDigraph, |
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[209] | 133 | typename TR=BfsDefaultTraits<GR> > |
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[100] | 134 | #endif |
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| 135 | class Bfs { |
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| 136 | public: |
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| 137 | |
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[244] | 138 | ///The type of the digraph the algorithm runs on. |
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[100] | 139 | typedef typename TR::Digraph Digraph; |
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[209] | 140 | |
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[244] | 141 | ///\brief The type of the map that stores the predecessor arcs of the |
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| 142 | ///shortest paths. |
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[100] | 143 | typedef typename TR::PredMap PredMap; |
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[244] | 144 | ///The type of the map that stores the distances of the nodes. |
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| 145 | typedef typename TR::DistMap DistMap; |
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| 146 | ///The type of the map that indicates which nodes are reached. |
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[100] | 147 | typedef typename TR::ReachedMap ReachedMap; |
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[244] | 148 | ///The type of the map that indicates which nodes are processed. |
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[100] | 149 | typedef typename TR::ProcessedMap ProcessedMap; |
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[244] | 150 | ///The type of the paths. |
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| 151 | typedef PredMapPath<Digraph, PredMap> Path; |
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| 152 | |
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| 153 | ///The traits class. |
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| 154 | typedef TR Traits; |
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| 155 | |
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[100] | 156 | private: |
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| 157 | |
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| 158 | typedef typename Digraph::Node Node; |
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| 159 | typedef typename Digraph::NodeIt NodeIt; |
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| 160 | typedef typename Digraph::Arc Arc; |
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| 161 | typedef typename Digraph::OutArcIt OutArcIt; |
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| 162 | |
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[244] | 163 | //Pointer to the underlying digraph. |
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[100] | 164 | const Digraph *G; |
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[244] | 165 | //Pointer to the map of predecessor arcs. |
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[100] | 166 | PredMap *_pred; |
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[244] | 167 | //Indicates if _pred is locally allocated (true) or not. |
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[100] | 168 | bool local_pred; |
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[244] | 169 | //Pointer to the map of distances. |
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[100] | 170 | DistMap *_dist; |
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[244] | 171 | //Indicates if _dist is locally allocated (true) or not. |
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[100] | 172 | bool local_dist; |
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[244] | 173 | //Pointer to the map of reached status of the nodes. |
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[100] | 174 | ReachedMap *_reached; |
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[244] | 175 | //Indicates if _reached is locally allocated (true) or not. |
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[100] | 176 | bool local_reached; |
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[244] | 177 | //Pointer to the map of processed status of the nodes. |
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[100] | 178 | ProcessedMap *_processed; |
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[244] | 179 | //Indicates if _processed is locally allocated (true) or not. |
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[100] | 180 | bool local_processed; |
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| 181 | |
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| 182 | std::vector<typename Digraph::Node> _queue; |
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| 183 | int _queue_head,_queue_tail,_queue_next_dist; |
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| 184 | int _curr_dist; |
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| 185 | |
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[280] | 186 | //Creates the maps if necessary. |
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[209] | 187 | void create_maps() |
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[100] | 188 | { |
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| 189 | if(!_pred) { |
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[209] | 190 | local_pred = true; |
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| 191 | _pred = Traits::createPredMap(*G); |
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[100] | 192 | } |
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| 193 | if(!_dist) { |
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[209] | 194 | local_dist = true; |
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| 195 | _dist = Traits::createDistMap(*G); |
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[100] | 196 | } |
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| 197 | if(!_reached) { |
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[209] | 198 | local_reached = true; |
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| 199 | _reached = Traits::createReachedMap(*G); |
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[100] | 200 | } |
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| 201 | if(!_processed) { |
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[209] | 202 | local_processed = true; |
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| 203 | _processed = Traits::createProcessedMap(*G); |
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[100] | 204 | } |
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| 205 | } |
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| 206 | |
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| 207 | protected: |
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[209] | 208 | |
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[100] | 209 | Bfs() {} |
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[209] | 210 | |
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[100] | 211 | public: |
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[209] | 212 | |
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[100] | 213 | typedef Bfs Create; |
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| 214 | |
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| 215 | ///\name Named template parameters |
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| 216 | |
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| 217 | ///@{ |
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| 218 | |
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| 219 | template <class T> |
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[257] | 220 | struct SetPredMapTraits : public Traits { |
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[100] | 221 | typedef T PredMap; |
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[209] | 222 | static PredMap *createPredMap(const Digraph &) |
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[100] | 223 | { |
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[290] | 224 | LEMON_ASSERT(false, "PredMap is not initialized"); |
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| 225 | return 0; // ignore warnings |
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[100] | 226 | } |
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| 227 | }; |
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| 228 | ///\brief \ref named-templ-param "Named parameter" for setting |
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[301] | 229 | ///PredMap type. |
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[100] | 230 | /// |
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[244] | 231 | ///\ref named-templ-param "Named parameter" for setting |
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[301] | 232 | ///PredMap type. |
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[100] | 233 | template <class T> |
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[257] | 234 | struct SetPredMap : public Bfs< Digraph, SetPredMapTraits<T> > { |
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| 235 | typedef Bfs< Digraph, SetPredMapTraits<T> > Create; |
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[100] | 236 | }; |
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[209] | 237 | |
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[100] | 238 | template <class T> |
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[257] | 239 | struct SetDistMapTraits : public Traits { |
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[100] | 240 | typedef T DistMap; |
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[209] | 241 | static DistMap *createDistMap(const Digraph &) |
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[100] | 242 | { |
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[290] | 243 | LEMON_ASSERT(false, "DistMap is not initialized"); |
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| 244 | return 0; // ignore warnings |
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[100] | 245 | } |
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| 246 | }; |
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| 247 | ///\brief \ref named-templ-param "Named parameter" for setting |
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[301] | 248 | ///DistMap type. |
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[100] | 249 | /// |
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[244] | 250 | ///\ref named-templ-param "Named parameter" for setting |
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[301] | 251 | ///DistMap type. |
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[100] | 252 | template <class T> |
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[257] | 253 | struct SetDistMap : public Bfs< Digraph, SetDistMapTraits<T> > { |
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| 254 | typedef Bfs< Digraph, SetDistMapTraits<T> > Create; |
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[100] | 255 | }; |
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[209] | 256 | |
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[100] | 257 | template <class T> |
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[257] | 258 | struct SetReachedMapTraits : public Traits { |
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[100] | 259 | typedef T ReachedMap; |
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[209] | 260 | static ReachedMap *createReachedMap(const Digraph &) |
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[100] | 261 | { |
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[290] | 262 | LEMON_ASSERT(false, "ReachedMap is not initialized"); |
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| 263 | return 0; // ignore warnings |
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[100] | 264 | } |
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| 265 | }; |
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| 266 | ///\brief \ref named-templ-param "Named parameter" for setting |
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[301] | 267 | ///ReachedMap type. |
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[100] | 268 | /// |
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[244] | 269 | ///\ref named-templ-param "Named parameter" for setting |
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[301] | 270 | ///ReachedMap type. |
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[100] | 271 | template <class T> |
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[257] | 272 | struct SetReachedMap : public Bfs< Digraph, SetReachedMapTraits<T> > { |
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| 273 | typedef Bfs< Digraph, SetReachedMapTraits<T> > Create; |
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[100] | 274 | }; |
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[209] | 275 | |
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[100] | 276 | template <class T> |
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[257] | 277 | struct SetProcessedMapTraits : public Traits { |
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[100] | 278 | typedef T ProcessedMap; |
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[209] | 279 | static ProcessedMap *createProcessedMap(const Digraph &) |
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[100] | 280 | { |
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[290] | 281 | LEMON_ASSERT(false, "ProcessedMap is not initialized"); |
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| 282 | return 0; // ignore warnings |
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[100] | 283 | } |
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| 284 | }; |
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| 285 | ///\brief \ref named-templ-param "Named parameter" for setting |
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[301] | 286 | ///ProcessedMap type. |
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[100] | 287 | /// |
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[244] | 288 | ///\ref named-templ-param "Named parameter" for setting |
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[301] | 289 | ///ProcessedMap type. |
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[100] | 290 | template <class T> |
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[257] | 291 | struct SetProcessedMap : public Bfs< Digraph, SetProcessedMapTraits<T> > { |
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| 292 | typedef Bfs< Digraph, SetProcessedMapTraits<T> > Create; |
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[100] | 293 | }; |
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[209] | 294 | |
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[257] | 295 | struct SetStandardProcessedMapTraits : public Traits { |
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[100] | 296 | typedef typename Digraph::template NodeMap<bool> ProcessedMap; |
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[244] | 297 | static ProcessedMap *createProcessedMap(const Digraph &g) |
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[100] | 298 | { |
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[244] | 299 | return new ProcessedMap(g); |
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[290] | 300 | return 0; // ignore warnings |
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[100] | 301 | } |
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| 302 | }; |
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[244] | 303 | ///\brief \ref named-templ-param "Named parameter" for setting |
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[301] | 304 | ///ProcessedMap type to be <tt>Digraph::NodeMap<bool></tt>. |
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[100] | 305 | /// |
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[244] | 306 | ///\ref named-templ-param "Named parameter" for setting |
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[301] | 307 | ///ProcessedMap type to be <tt>Digraph::NodeMap<bool></tt>. |
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[100] | 308 | ///If you don't set it explicitly, it will be automatically allocated. |
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[257] | 309 | struct SetStandardProcessedMap : |
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| 310 | public Bfs< Digraph, SetStandardProcessedMapTraits > { |
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| 311 | typedef Bfs< Digraph, SetStandardProcessedMapTraits > Create; |
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[100] | 312 | }; |
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[209] | 313 | |
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[100] | 314 | ///@} |
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| 315 | |
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[209] | 316 | public: |
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| 317 | |
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[100] | 318 | ///Constructor. |
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[209] | 319 | |
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[244] | 320 | ///Constructor. |
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| 321 | ///\param g The digraph the algorithm runs on. |
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| 322 | Bfs(const Digraph &g) : |
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| 323 | G(&g), |
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[100] | 324 | _pred(NULL), local_pred(false), |
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| 325 | _dist(NULL), local_dist(false), |
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| 326 | _reached(NULL), local_reached(false), |
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| 327 | _processed(NULL), local_processed(false) |
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| 328 | { } |
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[209] | 329 | |
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[100] | 330 | ///Destructor. |
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[209] | 331 | ~Bfs() |
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[100] | 332 | { |
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| 333 | if(local_pred) delete _pred; |
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| 334 | if(local_dist) delete _dist; |
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| 335 | if(local_reached) delete _reached; |
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| 336 | if(local_processed) delete _processed; |
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| 337 | } |
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| 338 | |
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[244] | 339 | ///Sets the map that stores the predecessor arcs. |
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[100] | 340 | |
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[244] | 341 | ///Sets the map that stores the predecessor arcs. |
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[100] | 342 | ///If you don't use this function before calling \ref run(), |
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| 343 | ///it will allocate one. The destructor deallocates this |
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| 344 | ///automatically allocated map, of course. |
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| 345 | ///\return <tt> (*this) </tt> |
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[209] | 346 | Bfs &predMap(PredMap &m) |
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[100] | 347 | { |
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| 348 | if(local_pred) { |
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[209] | 349 | delete _pred; |
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| 350 | local_pred=false; |
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[100] | 351 | } |
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| 352 | _pred = &m; |
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| 353 | return *this; |
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| 354 | } |
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| 355 | |
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[244] | 356 | ///Sets the map that indicates which nodes are reached. |
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[100] | 357 | |
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[244] | 358 | ///Sets the map that indicates which nodes are reached. |
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[100] | 359 | ///If you don't use this function before calling \ref run(), |
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| 360 | ///it will allocate one. The destructor deallocates this |
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| 361 | ///automatically allocated map, of course. |
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| 362 | ///\return <tt> (*this) </tt> |
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[209] | 363 | Bfs &reachedMap(ReachedMap &m) |
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[100] | 364 | { |
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| 365 | if(local_reached) { |
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[209] | 366 | delete _reached; |
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| 367 | local_reached=false; |
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[100] | 368 | } |
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| 369 | _reached = &m; |
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| 370 | return *this; |
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| 371 | } |
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| 372 | |
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[244] | 373 | ///Sets the map that indicates which nodes are processed. |
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[100] | 374 | |
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[244] | 375 | ///Sets the map that indicates which nodes are processed. |
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[100] | 376 | ///If you don't use this function before calling \ref run(), |
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| 377 | ///it will allocate one. The destructor deallocates this |
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| 378 | ///automatically allocated map, of course. |
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| 379 | ///\return <tt> (*this) </tt> |
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[209] | 380 | Bfs &processedMap(ProcessedMap &m) |
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[100] | 381 | { |
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| 382 | if(local_processed) { |
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[209] | 383 | delete _processed; |
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| 384 | local_processed=false; |
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[100] | 385 | } |
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| 386 | _processed = &m; |
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| 387 | return *this; |
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| 388 | } |
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| 389 | |
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[244] | 390 | ///Sets the map that stores the distances of the nodes. |
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[100] | 391 | |
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[244] | 392 | ///Sets the map that stores the distances of the nodes calculated by |
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| 393 | ///the algorithm. |
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[100] | 394 | ///If you don't use this function before calling \ref run(), |
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| 395 | ///it will allocate one. The destructor deallocates this |
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| 396 | ///automatically allocated map, of course. |
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| 397 | ///\return <tt> (*this) </tt> |
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[209] | 398 | Bfs &distMap(DistMap &m) |
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[100] | 399 | { |
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| 400 | if(local_dist) { |
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[209] | 401 | delete _dist; |
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| 402 | local_dist=false; |
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[100] | 403 | } |
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| 404 | _dist = &m; |
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| 405 | return *this; |
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| 406 | } |
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| 407 | |
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| 408 | public: |
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[244] | 409 | |
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[100] | 410 | ///\name Execution control |
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| 411 | ///The simplest way to execute the algorithm is to use |
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[244] | 412 | ///one of the member functions called \ref lemon::Bfs::run() "run()". |
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[100] | 413 | ///\n |
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[244] | 414 | ///If you need more control on the execution, first you must call |
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| 415 | ///\ref lemon::Bfs::init() "init()", then you can add several source |
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| 416 | ///nodes with \ref lemon::Bfs::addSource() "addSource()". |
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| 417 | ///Finally \ref lemon::Bfs::start() "start()" will perform the |
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| 418 | ///actual path computation. |
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[100] | 419 | |
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| 420 | ///@{ |
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| 421 | |
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[244] | 422 | ///Initializes the internal data structures. |
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| 423 | |
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[100] | 424 | ///Initializes the internal data structures. |
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| 425 | /// |
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| 426 | void init() |
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| 427 | { |
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| 428 | create_maps(); |
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| 429 | _queue.resize(countNodes(*G)); |
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| 430 | _queue_head=_queue_tail=0; |
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| 431 | _curr_dist=1; |
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| 432 | for ( NodeIt u(*G) ; u!=INVALID ; ++u ) { |
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[209] | 433 | _pred->set(u,INVALID); |
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| 434 | _reached->set(u,false); |
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| 435 | _processed->set(u,false); |
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[100] | 436 | } |
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| 437 | } |
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[209] | 438 | |
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[100] | 439 | ///Adds a new source node. |
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| 440 | |
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| 441 | ///Adds a new source node to the set of nodes to be processed. |
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| 442 | /// |
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| 443 | void addSource(Node s) |
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| 444 | { |
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| 445 | if(!(*_reached)[s]) |
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[209] | 446 | { |
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| 447 | _reached->set(s,true); |
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| 448 | _pred->set(s,INVALID); |
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| 449 | _dist->set(s,0); |
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| 450 | _queue[_queue_head++]=s; |
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| 451 | _queue_next_dist=_queue_head; |
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| 452 | } |
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[100] | 453 | } |
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[209] | 454 | |
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[100] | 455 | ///Processes the next node. |
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| 456 | |
---|
| 457 | ///Processes the next node. |
---|
| 458 | /// |
---|
| 459 | ///\return The processed node. |
---|
| 460 | /// |
---|
[244] | 461 | ///\pre The queue must not be empty. |
---|
[100] | 462 | Node processNextNode() |
---|
| 463 | { |
---|
| 464 | if(_queue_tail==_queue_next_dist) { |
---|
[209] | 465 | _curr_dist++; |
---|
| 466 | _queue_next_dist=_queue_head; |
---|
[100] | 467 | } |
---|
| 468 | Node n=_queue[_queue_tail++]; |
---|
| 469 | _processed->set(n,true); |
---|
| 470 | Node m; |
---|
| 471 | for(OutArcIt e(*G,n);e!=INVALID;++e) |
---|
[209] | 472 | if(!(*_reached)[m=G->target(e)]) { |
---|
| 473 | _queue[_queue_head++]=m; |
---|
| 474 | _reached->set(m,true); |
---|
| 475 | _pred->set(m,e); |
---|
| 476 | _dist->set(m,_curr_dist); |
---|
| 477 | } |
---|
[100] | 478 | return n; |
---|
| 479 | } |
---|
| 480 | |
---|
| 481 | ///Processes the next node. |
---|
| 482 | |
---|
[244] | 483 | ///Processes the next node and checks if the given target node |
---|
[100] | 484 | ///is reached. If the target node is reachable from the processed |
---|
[244] | 485 | ///node, then the \c reach parameter will be set to \c true. |
---|
[100] | 486 | /// |
---|
| 487 | ///\param target The target node. |
---|
[244] | 488 | ///\retval reach Indicates if the target node is reached. |
---|
| 489 | ///It should be initially \c false. |
---|
| 490 | /// |
---|
[100] | 491 | ///\return The processed node. |
---|
| 492 | /// |
---|
[244] | 493 | ///\pre The queue must not be empty. |
---|
[100] | 494 | Node processNextNode(Node target, bool& reach) |
---|
| 495 | { |
---|
| 496 | if(_queue_tail==_queue_next_dist) { |
---|
[209] | 497 | _curr_dist++; |
---|
| 498 | _queue_next_dist=_queue_head; |
---|
[100] | 499 | } |
---|
| 500 | Node n=_queue[_queue_tail++]; |
---|
| 501 | _processed->set(n,true); |
---|
| 502 | Node m; |
---|
| 503 | for(OutArcIt e(*G,n);e!=INVALID;++e) |
---|
[209] | 504 | if(!(*_reached)[m=G->target(e)]) { |
---|
| 505 | _queue[_queue_head++]=m; |
---|
| 506 | _reached->set(m,true); |
---|
| 507 | _pred->set(m,e); |
---|
| 508 | _dist->set(m,_curr_dist); |
---|
[100] | 509 | reach = reach || (target == m); |
---|
[209] | 510 | } |
---|
[100] | 511 | return n; |
---|
| 512 | } |
---|
| 513 | |
---|
| 514 | ///Processes the next node. |
---|
| 515 | |
---|
[244] | 516 | ///Processes the next node and checks if at least one of reached |
---|
| 517 | ///nodes has \c true value in the \c nm node map. If one node |
---|
| 518 | ///with \c true value is reachable from the processed node, then the |
---|
| 519 | ///\c rnode parameter will be set to the first of such nodes. |
---|
[100] | 520 | /// |
---|
[244] | 521 | ///\param nm A \c bool (or convertible) node map that indicates the |
---|
| 522 | ///possible targets. |
---|
[100] | 523 | ///\retval rnode The reached target node. |
---|
[244] | 524 | ///It should be initially \c INVALID. |
---|
| 525 | /// |
---|
[100] | 526 | ///\return The processed node. |
---|
| 527 | /// |
---|
[244] | 528 | ///\pre The queue must not be empty. |
---|
[100] | 529 | template<class NM> |
---|
| 530 | Node processNextNode(const NM& nm, Node& rnode) |
---|
| 531 | { |
---|
| 532 | if(_queue_tail==_queue_next_dist) { |
---|
[209] | 533 | _curr_dist++; |
---|
| 534 | _queue_next_dist=_queue_head; |
---|
[100] | 535 | } |
---|
| 536 | Node n=_queue[_queue_tail++]; |
---|
| 537 | _processed->set(n,true); |
---|
| 538 | Node m; |
---|
| 539 | for(OutArcIt e(*G,n);e!=INVALID;++e) |
---|
[209] | 540 | if(!(*_reached)[m=G->target(e)]) { |
---|
| 541 | _queue[_queue_head++]=m; |
---|
| 542 | _reached->set(m,true); |
---|
| 543 | _pred->set(m,e); |
---|
| 544 | _dist->set(m,_curr_dist); |
---|
| 545 | if (nm[m] && rnode == INVALID) rnode = m; |
---|
| 546 | } |
---|
[100] | 547 | return n; |
---|
| 548 | } |
---|
[209] | 549 | |
---|
[244] | 550 | ///The next node to be processed. |
---|
[100] | 551 | |
---|
[244] | 552 | ///Returns the next node to be processed or \c INVALID if the queue |
---|
| 553 | ///is empty. |
---|
| 554 | Node nextNode() const |
---|
[209] | 555 | { |
---|
[100] | 556 | return _queue_tail<_queue_head?_queue[_queue_tail]:INVALID; |
---|
| 557 | } |
---|
[209] | 558 | |
---|
[100] | 559 | ///\brief Returns \c false if there are nodes |
---|
[244] | 560 | ///to be processed. |
---|
[100] | 561 | /// |
---|
| 562 | ///Returns \c false if there are nodes |
---|
[244] | 563 | ///to be processed in the queue. |
---|
| 564 | bool emptyQueue() const { return _queue_tail==_queue_head; } |
---|
| 565 | |
---|
[100] | 566 | ///Returns the number of the nodes to be processed. |
---|
[209] | 567 | |
---|
[100] | 568 | ///Returns the number of the nodes to be processed in the queue. |
---|
[244] | 569 | int queueSize() const { return _queue_head-_queue_tail; } |
---|
[209] | 570 | |
---|
[100] | 571 | ///Executes the algorithm. |
---|
| 572 | |
---|
| 573 | ///Executes the algorithm. |
---|
| 574 | /// |
---|
[244] | 575 | ///This method runs the %BFS algorithm from the root node(s) |
---|
| 576 | ///in order to compute the shortest path to each node. |
---|
[100] | 577 | /// |
---|
[244] | 578 | ///The algorithm computes |
---|
| 579 | ///- the shortest path tree (forest), |
---|
| 580 | ///- the distance of each node from the root(s). |
---|
| 581 | /// |
---|
| 582 | ///\pre init() must be called and at least one root node should be |
---|
| 583 | ///added with addSource() before using this function. |
---|
| 584 | /// |
---|
| 585 | ///\note <tt>b.start()</tt> is just a shortcut of the following code. |
---|
| 586 | ///\code |
---|
| 587 | /// while ( !b.emptyQueue() ) { |
---|
| 588 | /// b.processNextNode(); |
---|
| 589 | /// } |
---|
| 590 | ///\endcode |
---|
[100] | 591 | void start() |
---|
| 592 | { |
---|
| 593 | while ( !emptyQueue() ) processNextNode(); |
---|
| 594 | } |
---|
[209] | 595 | |
---|
[244] | 596 | ///Executes the algorithm until the given target node is reached. |
---|
[100] | 597 | |
---|
[244] | 598 | ///Executes the algorithm until the given target node is reached. |
---|
[100] | 599 | /// |
---|
| 600 | ///This method runs the %BFS algorithm from the root node(s) |
---|
[286] | 601 | ///in order to compute the shortest path to \c t. |
---|
[244] | 602 | /// |
---|
[100] | 603 | ///The algorithm computes |
---|
[286] | 604 | ///- the shortest path to \c t, |
---|
| 605 | ///- the distance of \c t from the root(s). |
---|
[244] | 606 | /// |
---|
| 607 | ///\pre init() must be called and at least one root node should be |
---|
| 608 | ///added with addSource() before using this function. |
---|
| 609 | /// |
---|
| 610 | ///\note <tt>b.start(t)</tt> is just a shortcut of the following code. |
---|
| 611 | ///\code |
---|
| 612 | /// bool reach = false; |
---|
| 613 | /// while ( !b.emptyQueue() && !reach ) { |
---|
| 614 | /// b.processNextNode(t, reach); |
---|
| 615 | /// } |
---|
| 616 | ///\endcode |
---|
[286] | 617 | void start(Node t) |
---|
[100] | 618 | { |
---|
| 619 | bool reach = false; |
---|
[286] | 620 | while ( !emptyQueue() && !reach ) processNextNode(t, reach); |
---|
[100] | 621 | } |
---|
[209] | 622 | |
---|
[100] | 623 | ///Executes the algorithm until a condition is met. |
---|
| 624 | |
---|
| 625 | ///Executes the algorithm until a condition is met. |
---|
| 626 | /// |
---|
[244] | 627 | ///This method runs the %BFS algorithm from the root node(s) in |
---|
| 628 | ///order to compute the shortest path to a node \c v with |
---|
| 629 | /// <tt>nm[v]</tt> true, if such a node can be found. |
---|
[100] | 630 | /// |
---|
[244] | 631 | ///\param nm A \c bool (or convertible) node map. The algorithm |
---|
| 632 | ///will stop when it reaches a node \c v with <tt>nm[v]</tt> true. |
---|
[100] | 633 | /// |
---|
| 634 | ///\return The reached node \c v with <tt>nm[v]</tt> true or |
---|
| 635 | ///\c INVALID if no such node was found. |
---|
[244] | 636 | /// |
---|
| 637 | ///\pre init() must be called and at least one root node should be |
---|
| 638 | ///added with addSource() before using this function. |
---|
| 639 | /// |
---|
| 640 | ///\note <tt>b.start(nm)</tt> is just a shortcut of the following code. |
---|
| 641 | ///\code |
---|
| 642 | /// Node rnode = INVALID; |
---|
| 643 | /// while ( !b.emptyQueue() && rnode == INVALID ) { |
---|
| 644 | /// b.processNextNode(nm, rnode); |
---|
| 645 | /// } |
---|
| 646 | /// return rnode; |
---|
| 647 | ///\endcode |
---|
| 648 | template<class NodeBoolMap> |
---|
| 649 | Node start(const NodeBoolMap &nm) |
---|
[100] | 650 | { |
---|
| 651 | Node rnode = INVALID; |
---|
| 652 | while ( !emptyQueue() && rnode == INVALID ) { |
---|
[209] | 653 | processNextNode(nm, rnode); |
---|
[100] | 654 | } |
---|
| 655 | return rnode; |
---|
| 656 | } |
---|
[209] | 657 | |
---|
[286] | 658 | ///Runs the algorithm from the given source node. |
---|
[209] | 659 | |
---|
[244] | 660 | ///This method runs the %BFS algorithm from node \c s |
---|
| 661 | ///in order to compute the shortest path to each node. |
---|
[100] | 662 | /// |
---|
[244] | 663 | ///The algorithm computes |
---|
| 664 | ///- the shortest path tree, |
---|
| 665 | ///- the distance of each node from the root. |
---|
| 666 | /// |
---|
| 667 | ///\note <tt>b.run(s)</tt> is just a shortcut of the following code. |
---|
[100] | 668 | ///\code |
---|
| 669 | /// b.init(); |
---|
| 670 | /// b.addSource(s); |
---|
| 671 | /// b.start(); |
---|
| 672 | ///\endcode |
---|
| 673 | void run(Node s) { |
---|
| 674 | init(); |
---|
| 675 | addSource(s); |
---|
| 676 | start(); |
---|
| 677 | } |
---|
[209] | 678 | |
---|
[100] | 679 | ///Finds the shortest path between \c s and \c t. |
---|
[209] | 680 | |
---|
[244] | 681 | ///This method runs the %BFS algorithm from node \c s |
---|
[286] | 682 | ///in order to compute the shortest path to node \c t |
---|
| 683 | ///(it stops searching when \c t is processed). |
---|
[100] | 684 | /// |
---|
[286] | 685 | ///\return \c true if \c t is reachable form \c s. |
---|
[244] | 686 | /// |
---|
| 687 | ///\note Apart from the return value, <tt>b.run(s,t)</tt> is just a |
---|
| 688 | ///shortcut of the following code. |
---|
[100] | 689 | ///\code |
---|
| 690 | /// b.init(); |
---|
| 691 | /// b.addSource(s); |
---|
| 692 | /// b.start(t); |
---|
| 693 | ///\endcode |
---|
[286] | 694 | bool run(Node s,Node t) { |
---|
[100] | 695 | init(); |
---|
| 696 | addSource(s); |
---|
| 697 | start(t); |
---|
[286] | 698 | return reached(t); |
---|
[100] | 699 | } |
---|
[209] | 700 | |
---|
[244] | 701 | ///Runs the algorithm to visit all nodes in the digraph. |
---|
| 702 | |
---|
| 703 | ///This method runs the %BFS algorithm in order to |
---|
| 704 | ///compute the shortest path to each node. |
---|
| 705 | /// |
---|
| 706 | ///The algorithm computes |
---|
| 707 | ///- the shortest path tree (forest), |
---|
| 708 | ///- the distance of each node from the root(s). |
---|
| 709 | /// |
---|
| 710 | ///\note <tt>b.run(s)</tt> is just a shortcut of the following code. |
---|
| 711 | ///\code |
---|
| 712 | /// b.init(); |
---|
| 713 | /// for (NodeIt n(gr); n != INVALID; ++n) { |
---|
| 714 | /// if (!b.reached(n)) { |
---|
| 715 | /// b.addSource(n); |
---|
| 716 | /// b.start(); |
---|
| 717 | /// } |
---|
| 718 | /// } |
---|
| 719 | ///\endcode |
---|
| 720 | void run() { |
---|
| 721 | init(); |
---|
| 722 | for (NodeIt n(*G); n != INVALID; ++n) { |
---|
| 723 | if (!reached(n)) { |
---|
| 724 | addSource(n); |
---|
| 725 | start(); |
---|
| 726 | } |
---|
| 727 | } |
---|
| 728 | } |
---|
| 729 | |
---|
[100] | 730 | ///@} |
---|
| 731 | |
---|
| 732 | ///\name Query Functions |
---|
| 733 | ///The result of the %BFS algorithm can be obtained using these |
---|
| 734 | ///functions.\n |
---|
[244] | 735 | ///Either \ref lemon::Bfs::run() "run()" or \ref lemon::Bfs::start() |
---|
| 736 | ///"start()" must be called before using them. |
---|
[209] | 737 | |
---|
[100] | 738 | ///@{ |
---|
| 739 | |
---|
[244] | 740 | ///The shortest path to a node. |
---|
[100] | 741 | |
---|
[244] | 742 | ///Returns the shortest path to a node. |
---|
| 743 | /// |
---|
| 744 | ///\warning \c t should be reachable from the root(s). |
---|
| 745 | /// |
---|
| 746 | ///\pre Either \ref run() or \ref start() must be called before |
---|
| 747 | ///using this function. |
---|
| 748 | Path path(Node t) const { return Path(*G, *_pred, t); } |
---|
[100] | 749 | |
---|
| 750 | ///The distance of a node from the root(s). |
---|
| 751 | |
---|
| 752 | ///Returns the distance of a node from the root(s). |
---|
[244] | 753 | /// |
---|
| 754 | ///\warning If node \c v is not reachable from the root(s), then |
---|
| 755 | ///the return value of this function is undefined. |
---|
| 756 | /// |
---|
| 757 | ///\pre Either \ref run() or \ref start() must be called before |
---|
| 758 | ///using this function. |
---|
[100] | 759 | int dist(Node v) const { return (*_dist)[v]; } |
---|
| 760 | |
---|
[244] | 761 | ///Returns the 'previous arc' of the shortest path tree for a node. |
---|
[100] | 762 | |
---|
[244] | 763 | ///This function returns the 'previous arc' of the shortest path |
---|
| 764 | ///tree for the node \c v, i.e. it returns the last arc of a |
---|
| 765 | ///shortest path from the root(s) to \c v. It is \c INVALID if \c v |
---|
| 766 | ///is not reachable from the root(s) or if \c v is a root. |
---|
| 767 | /// |
---|
| 768 | ///The shortest path tree used here is equal to the shortest path |
---|
| 769 | ///tree used in \ref predNode(). |
---|
| 770 | /// |
---|
| 771 | ///\pre Either \ref run() or \ref start() must be called before |
---|
| 772 | ///using this function. |
---|
[100] | 773 | Arc predArc(Node v) const { return (*_pred)[v];} |
---|
| 774 | |
---|
[244] | 775 | ///Returns the 'previous node' of the shortest path tree for a node. |
---|
[100] | 776 | |
---|
[244] | 777 | ///This function returns the 'previous node' of the shortest path |
---|
| 778 | ///tree for the node \c v, i.e. it returns the last but one node |
---|
| 779 | ///from a shortest path from the root(s) to \c v. It is \c INVALID |
---|
| 780 | ///if \c v is not reachable from the root(s) or if \c v is a root. |
---|
| 781 | /// |
---|
[100] | 782 | ///The shortest path tree used here is equal to the shortest path |
---|
| 783 | ///tree used in \ref predArc(). |
---|
[244] | 784 | /// |
---|
[100] | 785 | ///\pre Either \ref run() or \ref start() must be called before |
---|
| 786 | ///using this function. |
---|
| 787 | Node predNode(Node v) const { return (*_pred)[v]==INVALID ? INVALID: |
---|
[209] | 788 | G->source((*_pred)[v]); } |
---|
| 789 | |
---|
[244] | 790 | ///\brief Returns a const reference to the node map that stores the |
---|
| 791 | /// distances of the nodes. |
---|
| 792 | /// |
---|
| 793 | ///Returns a const reference to the node map that stores the distances |
---|
| 794 | ///of the nodes calculated by the algorithm. |
---|
| 795 | /// |
---|
| 796 | ///\pre Either \ref run() or \ref init() |
---|
| 797 | ///must be called before using this function. |
---|
[100] | 798 | const DistMap &distMap() const { return *_dist;} |
---|
[209] | 799 | |
---|
[244] | 800 | ///\brief Returns a const reference to the node map that stores the |
---|
| 801 | ///predecessor arcs. |
---|
| 802 | /// |
---|
| 803 | ///Returns a const reference to the node map that stores the predecessor |
---|
| 804 | ///arcs, which form the shortest path tree. |
---|
| 805 | /// |
---|
[100] | 806 | ///\pre Either \ref run() or \ref init() |
---|
| 807 | ///must be called before using this function. |
---|
| 808 | const PredMap &predMap() const { return *_pred;} |
---|
[209] | 809 | |
---|
[244] | 810 | ///Checks if a node is reachable from the root(s). |
---|
[100] | 811 | |
---|
[244] | 812 | ///Returns \c true if \c v is reachable from the root(s). |
---|
[100] | 813 | ///\pre Either \ref run() or \ref start() |
---|
| 814 | ///must be called before using this function. |
---|
[244] | 815 | bool reached(Node v) const { return (*_reached)[v]; } |
---|
[209] | 816 | |
---|
[100] | 817 | ///@} |
---|
| 818 | }; |
---|
| 819 | |
---|
[244] | 820 | ///Default traits class of bfs() function. |
---|
[100] | 821 | |
---|
[244] | 822 | ///Default traits class of bfs() function. |
---|
[157] | 823 | ///\tparam GR Digraph type. |
---|
[100] | 824 | template<class GR> |
---|
| 825 | struct BfsWizardDefaultTraits |
---|
| 826 | { |
---|
[244] | 827 | ///The type of the digraph the algorithm runs on. |
---|
[100] | 828 | typedef GR Digraph; |
---|
[244] | 829 | |
---|
| 830 | ///\brief The type of the map that stores the predecessor |
---|
[100] | 831 | ///arcs of the shortest paths. |
---|
[209] | 832 | /// |
---|
[244] | 833 | ///The type of the map that stores the predecessor |
---|
[100] | 834 | ///arcs of the shortest paths. |
---|
| 835 | ///It must meet the \ref concepts::WriteMap "WriteMap" concept. |
---|
[278] | 836 | typedef typename Digraph::template NodeMap<typename Digraph::Arc> PredMap; |
---|
[301] | 837 | ///Instantiates a PredMap. |
---|
[209] | 838 | |
---|
[301] | 839 | ///This function instantiates a PredMap. |
---|
[244] | 840 | ///\param g is the digraph, to which we would like to define the |
---|
[301] | 841 | ///PredMap. |
---|
[244] | 842 | static PredMap *createPredMap(const Digraph &g) |
---|
[100] | 843 | { |
---|
[278] | 844 | return new PredMap(g); |
---|
[100] | 845 | } |
---|
| 846 | |
---|
| 847 | ///The type of the map that indicates which nodes are processed. |
---|
[209] | 848 | |
---|
[100] | 849 | ///The type of the map that indicates which nodes are processed. |
---|
| 850 | ///It must meet the \ref concepts::WriteMap "WriteMap" concept. |
---|
[278] | 851 | ///By default it is a NullMap. |
---|
[100] | 852 | typedef NullMap<typename Digraph::Node,bool> ProcessedMap; |
---|
[301] | 853 | ///Instantiates a ProcessedMap. |
---|
[209] | 854 | |
---|
[301] | 855 | ///This function instantiates a ProcessedMap. |
---|
[100] | 856 | ///\param g is the digraph, to which |
---|
[301] | 857 | ///we would like to define the ProcessedMap. |
---|
[100] | 858 | #ifdef DOXYGEN |
---|
[244] | 859 | static ProcessedMap *createProcessedMap(const Digraph &g) |
---|
[100] | 860 | #else |
---|
[244] | 861 | static ProcessedMap *createProcessedMap(const Digraph &) |
---|
[100] | 862 | #endif |
---|
| 863 | { |
---|
| 864 | return new ProcessedMap(); |
---|
| 865 | } |
---|
[244] | 866 | |
---|
[100] | 867 | ///The type of the map that indicates which nodes are reached. |
---|
[209] | 868 | |
---|
[100] | 869 | ///The type of the map that indicates which nodes are reached. |
---|
[244] | 870 | ///It must meet the \ref concepts::ReadWriteMap "ReadWriteMap" concept. |
---|
[100] | 871 | typedef typename Digraph::template NodeMap<bool> ReachedMap; |
---|
[301] | 872 | ///Instantiates a ReachedMap. |
---|
[209] | 873 | |
---|
[301] | 874 | ///This function instantiates a ReachedMap. |
---|
[244] | 875 | ///\param g is the digraph, to which |
---|
[301] | 876 | ///we would like to define the ReachedMap. |
---|
[244] | 877 | static ReachedMap *createReachedMap(const Digraph &g) |
---|
[100] | 878 | { |
---|
[244] | 879 | return new ReachedMap(g); |
---|
[100] | 880 | } |
---|
[209] | 881 | |
---|
[244] | 882 | ///The type of the map that stores the distances of the nodes. |
---|
| 883 | |
---|
| 884 | ///The type of the map that stores the distances of the nodes. |
---|
[100] | 885 | ///It must meet the \ref concepts::WriteMap "WriteMap" concept. |
---|
[278] | 886 | typedef typename Digraph::template NodeMap<int> DistMap; |
---|
[301] | 887 | ///Instantiates a DistMap. |
---|
[209] | 888 | |
---|
[301] | 889 | ///This function instantiates a DistMap. |
---|
[210] | 890 | ///\param g is the digraph, to which we would like to define |
---|
[301] | 891 | ///the DistMap |
---|
[244] | 892 | static DistMap *createDistMap(const Digraph &g) |
---|
[100] | 893 | { |
---|
[278] | 894 | return new DistMap(g); |
---|
[100] | 895 | } |
---|
[278] | 896 | |
---|
| 897 | ///The type of the shortest paths. |
---|
| 898 | |
---|
| 899 | ///The type of the shortest paths. |
---|
| 900 | ///It must meet the \ref concepts::Path "Path" concept. |
---|
| 901 | typedef lemon::Path<Digraph> Path; |
---|
[100] | 902 | }; |
---|
[209] | 903 | |
---|
[301] | 904 | /// Default traits class used by BfsWizard |
---|
[100] | 905 | |
---|
| 906 | /// To make it easier to use Bfs algorithm |
---|
[244] | 907 | /// we have created a wizard class. |
---|
[100] | 908 | /// This \ref BfsWizard class needs default traits, |
---|
[244] | 909 | /// as well as the \ref Bfs class. |
---|
[100] | 910 | /// The \ref BfsWizardBase is a class to be the default traits of the |
---|
| 911 | /// \ref BfsWizard class. |
---|
| 912 | template<class GR> |
---|
| 913 | class BfsWizardBase : public BfsWizardDefaultTraits<GR> |
---|
| 914 | { |
---|
| 915 | |
---|
| 916 | typedef BfsWizardDefaultTraits<GR> Base; |
---|
| 917 | protected: |
---|
[244] | 918 | //The type of the nodes in the digraph. |
---|
[100] | 919 | typedef typename Base::Digraph::Node Node; |
---|
| 920 | |
---|
[244] | 921 | //Pointer to the digraph the algorithm runs on. |
---|
[100] | 922 | void *_g; |
---|
[244] | 923 | //Pointer to the map of reached nodes. |
---|
[100] | 924 | void *_reached; |
---|
[244] | 925 | //Pointer to the map of processed nodes. |
---|
[100] | 926 | void *_processed; |
---|
[244] | 927 | //Pointer to the map of predecessors arcs. |
---|
[100] | 928 | void *_pred; |
---|
[244] | 929 | //Pointer to the map of distances. |
---|
[100] | 930 | void *_dist; |
---|
[278] | 931 | //Pointer to the shortest path to the target node. |
---|
| 932 | void *_path; |
---|
| 933 | //Pointer to the distance of the target node. |
---|
| 934 | int *_di; |
---|
[209] | 935 | |
---|
[100] | 936 | public: |
---|
| 937 | /// Constructor. |
---|
[209] | 938 | |
---|
[100] | 939 | /// This constructor does not require parameters, therefore it initiates |
---|
[278] | 940 | /// all of the attributes to \c 0. |
---|
[100] | 941 | BfsWizardBase() : _g(0), _reached(0), _processed(0), _pred(0), |
---|
[278] | 942 | _dist(0), _path(0), _di(0) {} |
---|
[100] | 943 | |
---|
| 944 | /// Constructor. |
---|
[209] | 945 | |
---|
[278] | 946 | /// This constructor requires one parameter, |
---|
| 947 | /// others are initiated to \c 0. |
---|
[244] | 948 | /// \param g The digraph the algorithm runs on. |
---|
[278] | 949 | BfsWizardBase(const GR &g) : |
---|
[209] | 950 | _g(reinterpret_cast<void*>(const_cast<GR*>(&g))), |
---|
[278] | 951 | _reached(0), _processed(0), _pred(0), _dist(0), _path(0), _di(0) {} |
---|
[100] | 952 | |
---|
| 953 | }; |
---|
[209] | 954 | |
---|
[278] | 955 | /// Auxiliary class for the function-type interface of BFS algorithm. |
---|
[100] | 956 | |
---|
[278] | 957 | /// This auxiliary class is created to implement the |
---|
| 958 | /// \ref bfs() "function-type interface" of \ref Bfs algorithm. |
---|
| 959 | /// It does not have own \ref run() method, it uses the functions |
---|
| 960 | /// and features of the plain \ref Bfs. |
---|
[100] | 961 | /// |
---|
[278] | 962 | /// This class should only be used through the \ref bfs() function, |
---|
| 963 | /// which makes it easier to use the algorithm. |
---|
[100] | 964 | template<class TR> |
---|
| 965 | class BfsWizard : public TR |
---|
| 966 | { |
---|
| 967 | typedef TR Base; |
---|
| 968 | |
---|
[244] | 969 | ///The type of the digraph the algorithm runs on. |
---|
[100] | 970 | typedef typename TR::Digraph Digraph; |
---|
[244] | 971 | |
---|
[100] | 972 | typedef typename Digraph::Node Node; |
---|
| 973 | typedef typename Digraph::NodeIt NodeIt; |
---|
| 974 | typedef typename Digraph::Arc Arc; |
---|
| 975 | typedef typename Digraph::OutArcIt OutArcIt; |
---|
[209] | 976 | |
---|
[244] | 977 | ///\brief The type of the map that stores the predecessor |
---|
[100] | 978 | ///arcs of the shortest paths. |
---|
| 979 | typedef typename TR::PredMap PredMap; |
---|
[244] | 980 | ///\brief The type of the map that stores the distances of the nodes. |
---|
[100] | 981 | typedef typename TR::DistMap DistMap; |
---|
[244] | 982 | ///\brief The type of the map that indicates which nodes are reached. |
---|
| 983 | typedef typename TR::ReachedMap ReachedMap; |
---|
| 984 | ///\brief The type of the map that indicates which nodes are processed. |
---|
| 985 | typedef typename TR::ProcessedMap ProcessedMap; |
---|
[278] | 986 | ///The type of the shortest paths |
---|
| 987 | typedef typename TR::Path Path; |
---|
[100] | 988 | |
---|
| 989 | public: |
---|
[244] | 990 | |
---|
[100] | 991 | /// Constructor. |
---|
| 992 | BfsWizard() : TR() {} |
---|
| 993 | |
---|
| 994 | /// Constructor that requires parameters. |
---|
| 995 | |
---|
| 996 | /// Constructor that requires parameters. |
---|
| 997 | /// These parameters will be the default values for the traits class. |
---|
[278] | 998 | /// \param g The digraph the algorithm runs on. |
---|
| 999 | BfsWizard(const Digraph &g) : |
---|
| 1000 | TR(g) {} |
---|
[100] | 1001 | |
---|
| 1002 | ///Copy constructor |
---|
| 1003 | BfsWizard(const TR &b) : TR(b) {} |
---|
| 1004 | |
---|
| 1005 | ~BfsWizard() {} |
---|
| 1006 | |
---|
[278] | 1007 | ///Runs BFS algorithm from the given source node. |
---|
[209] | 1008 | |
---|
[278] | 1009 | ///This method runs BFS algorithm from node \c s |
---|
| 1010 | ///in order to compute the shortest path to each node. |
---|
| 1011 | void run(Node s) |
---|
| 1012 | { |
---|
| 1013 | Bfs<Digraph,TR> alg(*reinterpret_cast<const Digraph*>(Base::_g)); |
---|
| 1014 | if (Base::_pred) |
---|
| 1015 | alg.predMap(*reinterpret_cast<PredMap*>(Base::_pred)); |
---|
| 1016 | if (Base::_dist) |
---|
| 1017 | alg.distMap(*reinterpret_cast<DistMap*>(Base::_dist)); |
---|
| 1018 | if (Base::_reached) |
---|
| 1019 | alg.reachedMap(*reinterpret_cast<ReachedMap*>(Base::_reached)); |
---|
| 1020 | if (Base::_processed) |
---|
| 1021 | alg.processedMap(*reinterpret_cast<ProcessedMap*>(Base::_processed)); |
---|
| 1022 | if (s!=INVALID) |
---|
| 1023 | alg.run(s); |
---|
| 1024 | else |
---|
| 1025 | alg.run(); |
---|
| 1026 | } |
---|
| 1027 | |
---|
| 1028 | ///Finds the shortest path between \c s and \c t. |
---|
| 1029 | |
---|
| 1030 | ///This method runs BFS algorithm from node \c s |
---|
| 1031 | ///in order to compute the shortest path to node \c t |
---|
| 1032 | ///(it stops searching when \c t is processed). |
---|
| 1033 | /// |
---|
| 1034 | ///\return \c true if \c t is reachable form \c s. |
---|
| 1035 | bool run(Node s, Node t) |
---|
| 1036 | { |
---|
| 1037 | Bfs<Digraph,TR> alg(*reinterpret_cast<const Digraph*>(Base::_g)); |
---|
| 1038 | if (Base::_pred) |
---|
| 1039 | alg.predMap(*reinterpret_cast<PredMap*>(Base::_pred)); |
---|
| 1040 | if (Base::_dist) |
---|
| 1041 | alg.distMap(*reinterpret_cast<DistMap*>(Base::_dist)); |
---|
| 1042 | if (Base::_reached) |
---|
| 1043 | alg.reachedMap(*reinterpret_cast<ReachedMap*>(Base::_reached)); |
---|
| 1044 | if (Base::_processed) |
---|
| 1045 | alg.processedMap(*reinterpret_cast<ProcessedMap*>(Base::_processed)); |
---|
| 1046 | alg.run(s,t); |
---|
| 1047 | if (Base::_path) |
---|
| 1048 | *reinterpret_cast<Path*>(Base::_path) = alg.path(t); |
---|
| 1049 | if (Base::_di) |
---|
| 1050 | *Base::_di = alg.dist(t); |
---|
| 1051 | return alg.reached(t); |
---|
| 1052 | } |
---|
| 1053 | |
---|
| 1054 | ///Runs BFS algorithm to visit all nodes in the digraph. |
---|
| 1055 | |
---|
| 1056 | ///This method runs BFS algorithm in order to compute |
---|
| 1057 | ///the shortest path to each node. |
---|
[100] | 1058 | void run() |
---|
| 1059 | { |
---|
[278] | 1060 | run(INVALID); |
---|
[100] | 1061 | } |
---|
[209] | 1062 | |
---|
[244] | 1063 | template<class T> |
---|
[257] | 1064 | struct SetPredMapBase : public Base { |
---|
[244] | 1065 | typedef T PredMap; |
---|
| 1066 | static PredMap *createPredMap(const Digraph &) { return 0; }; |
---|
[257] | 1067 | SetPredMapBase(const TR &b) : TR(b) {} |
---|
[244] | 1068 | }; |
---|
[278] | 1069 | ///\brief \ref named-func-param "Named parameter" |
---|
[301] | 1070 | ///for setting PredMap object. |
---|
[244] | 1071 | /// |
---|
[278] | 1072 | ///\ref named-func-param "Named parameter" |
---|
[301] | 1073 | ///for setting PredMap object. |
---|
[244] | 1074 | template<class T> |
---|
[257] | 1075 | BfsWizard<SetPredMapBase<T> > predMap(const T &t) |
---|
[244] | 1076 | { |
---|
| 1077 | Base::_pred=reinterpret_cast<void*>(const_cast<T*>(&t)); |
---|
[257] | 1078 | return BfsWizard<SetPredMapBase<T> >(*this); |
---|
[244] | 1079 | } |
---|
| 1080 | |
---|
| 1081 | template<class T> |
---|
[257] | 1082 | struct SetReachedMapBase : public Base { |
---|
[244] | 1083 | typedef T ReachedMap; |
---|
| 1084 | static ReachedMap *createReachedMap(const Digraph &) { return 0; }; |
---|
[257] | 1085 | SetReachedMapBase(const TR &b) : TR(b) {} |
---|
[244] | 1086 | }; |
---|
[278] | 1087 | ///\brief \ref named-func-param "Named parameter" |
---|
[301] | 1088 | ///for setting ReachedMap object. |
---|
[244] | 1089 | /// |
---|
[278] | 1090 | /// \ref named-func-param "Named parameter" |
---|
[301] | 1091 | ///for setting ReachedMap object. |
---|
[244] | 1092 | template<class T> |
---|
[257] | 1093 | BfsWizard<SetReachedMapBase<T> > reachedMap(const T &t) |
---|
[244] | 1094 | { |
---|
| 1095 | Base::_reached=reinterpret_cast<void*>(const_cast<T*>(&t)); |
---|
[257] | 1096 | return BfsWizard<SetReachedMapBase<T> >(*this); |
---|
[244] | 1097 | } |
---|
| 1098 | |
---|
| 1099 | template<class T> |
---|
[278] | 1100 | struct SetDistMapBase : public Base { |
---|
| 1101 | typedef T DistMap; |
---|
| 1102 | static DistMap *createDistMap(const Digraph &) { return 0; }; |
---|
| 1103 | SetDistMapBase(const TR &b) : TR(b) {} |
---|
| 1104 | }; |
---|
| 1105 | ///\brief \ref named-func-param "Named parameter" |
---|
[301] | 1106 | ///for setting DistMap object. |
---|
[278] | 1107 | /// |
---|
| 1108 | /// \ref named-func-param "Named parameter" |
---|
[301] | 1109 | ///for setting DistMap object. |
---|
[278] | 1110 | template<class T> |
---|
| 1111 | BfsWizard<SetDistMapBase<T> > distMap(const T &t) |
---|
| 1112 | { |
---|
| 1113 | Base::_dist=reinterpret_cast<void*>(const_cast<T*>(&t)); |
---|
| 1114 | return BfsWizard<SetDistMapBase<T> >(*this); |
---|
| 1115 | } |
---|
| 1116 | |
---|
| 1117 | template<class T> |
---|
[257] | 1118 | struct SetProcessedMapBase : public Base { |
---|
[244] | 1119 | typedef T ProcessedMap; |
---|
| 1120 | static ProcessedMap *createProcessedMap(const Digraph &) { return 0; }; |
---|
[257] | 1121 | SetProcessedMapBase(const TR &b) : TR(b) {} |
---|
[244] | 1122 | }; |
---|
[278] | 1123 | ///\brief \ref named-func-param "Named parameter" |
---|
[301] | 1124 | ///for setting ProcessedMap object. |
---|
[244] | 1125 | /// |
---|
[278] | 1126 | /// \ref named-func-param "Named parameter" |
---|
[301] | 1127 | ///for setting ProcessedMap object. |
---|
[244] | 1128 | template<class T> |
---|
[257] | 1129 | BfsWizard<SetProcessedMapBase<T> > processedMap(const T &t) |
---|
[244] | 1130 | { |
---|
| 1131 | Base::_processed=reinterpret_cast<void*>(const_cast<T*>(&t)); |
---|
[257] | 1132 | return BfsWizard<SetProcessedMapBase<T> >(*this); |
---|
[244] | 1133 | } |
---|
| 1134 | |
---|
| 1135 | template<class T> |
---|
[278] | 1136 | struct SetPathBase : public Base { |
---|
| 1137 | typedef T Path; |
---|
| 1138 | SetPathBase(const TR &b) : TR(b) {} |
---|
[244] | 1139 | }; |
---|
[278] | 1140 | ///\brief \ref named-func-param "Named parameter" |
---|
| 1141 | ///for getting the shortest path to the target node. |
---|
[244] | 1142 | /// |
---|
[278] | 1143 | ///\ref named-func-param "Named parameter" |
---|
| 1144 | ///for getting the shortest path to the target node. |
---|
[244] | 1145 | template<class T> |
---|
[278] | 1146 | BfsWizard<SetPathBase<T> > path(const T &t) |
---|
[244] | 1147 | { |
---|
[278] | 1148 | Base::_path=reinterpret_cast<void*>(const_cast<T*>(&t)); |
---|
| 1149 | return BfsWizard<SetPathBase<T> >(*this); |
---|
| 1150 | } |
---|
| 1151 | |
---|
| 1152 | ///\brief \ref named-func-param "Named parameter" |
---|
| 1153 | ///for getting the distance of the target node. |
---|
| 1154 | /// |
---|
| 1155 | ///\ref named-func-param "Named parameter" |
---|
| 1156 | ///for getting the distance of the target node. |
---|
| 1157 | BfsWizard dist(const int &d) |
---|
| 1158 | { |
---|
| 1159 | Base::_di=const_cast<int*>(&d); |
---|
| 1160 | return *this; |
---|
[244] | 1161 | } |
---|
| 1162 | |
---|
[100] | 1163 | }; |
---|
[209] | 1164 | |
---|
[278] | 1165 | ///Function-type interface for BFS algorithm. |
---|
[100] | 1166 | |
---|
| 1167 | /// \ingroup search |
---|
[278] | 1168 | ///Function-type interface for BFS algorithm. |
---|
[100] | 1169 | /// |
---|
[278] | 1170 | ///This function also has several \ref named-func-param "named parameters", |
---|
[100] | 1171 | ///they are declared as the members of class \ref BfsWizard. |
---|
[278] | 1172 | ///The following examples show how to use these parameters. |
---|
[100] | 1173 | ///\code |
---|
[278] | 1174 | /// // Compute shortest path from node s to each node |
---|
| 1175 | /// bfs(g).predMap(preds).distMap(dists).run(s); |
---|
| 1176 | /// |
---|
| 1177 | /// // Compute shortest path from s to t |
---|
| 1178 | /// bool reached = bfs(g).path(p).dist(d).run(s,t); |
---|
[100] | 1179 | ///\endcode |
---|
| 1180 | ///\warning Don't forget to put the \ref BfsWizard::run() "run()" |
---|
| 1181 | ///to the end of the parameter list. |
---|
| 1182 | ///\sa BfsWizard |
---|
| 1183 | ///\sa Bfs |
---|
| 1184 | template<class GR> |
---|
| 1185 | BfsWizard<BfsWizardBase<GR> > |
---|
[278] | 1186 | bfs(const GR &digraph) |
---|
[100] | 1187 | { |
---|
[278] | 1188 | return BfsWizard<BfsWizardBase<GR> >(digraph); |
---|
[100] | 1189 | } |
---|
| 1190 | |
---|
| 1191 | #ifdef DOXYGEN |
---|
[244] | 1192 | /// \brief Visitor class for BFS. |
---|
[209] | 1193 | /// |
---|
[100] | 1194 | /// This class defines the interface of the BfsVisit events, and |
---|
[244] | 1195 | /// it could be the base of a real visitor class. |
---|
[100] | 1196 | template <typename _Digraph> |
---|
| 1197 | struct BfsVisitor { |
---|
| 1198 | typedef _Digraph Digraph; |
---|
| 1199 | typedef typename Digraph::Arc Arc; |
---|
| 1200 | typedef typename Digraph::Node Node; |
---|
[244] | 1201 | /// \brief Called for the source node(s) of the BFS. |
---|
[209] | 1202 | /// |
---|
[244] | 1203 | /// This function is called for the source node(s) of the BFS. |
---|
| 1204 | void start(const Node& node) {} |
---|
| 1205 | /// \brief Called when a node is reached first time. |
---|
| 1206 | /// |
---|
| 1207 | /// This function is called when a node is reached first time. |
---|
| 1208 | void reach(const Node& node) {} |
---|
| 1209 | /// \brief Called when a node is processed. |
---|
| 1210 | /// |
---|
| 1211 | /// This function is called when a node is processed. |
---|
| 1212 | void process(const Node& node) {} |
---|
| 1213 | /// \brief Called when an arc reaches a new node. |
---|
| 1214 | /// |
---|
| 1215 | /// This function is called when the BFS finds an arc whose target node |
---|
| 1216 | /// is not reached yet. |
---|
[100] | 1217 | void discover(const Arc& arc) {} |
---|
[244] | 1218 | /// \brief Called when an arc is examined but its target node is |
---|
[100] | 1219 | /// already discovered. |
---|
[209] | 1220 | /// |
---|
[244] | 1221 | /// This function is called when an arc is examined but its target node is |
---|
[100] | 1222 | /// already discovered. |
---|
| 1223 | void examine(const Arc& arc) {} |
---|
| 1224 | }; |
---|
| 1225 | #else |
---|
| 1226 | template <typename _Digraph> |
---|
| 1227 | struct BfsVisitor { |
---|
| 1228 | typedef _Digraph Digraph; |
---|
| 1229 | typedef typename Digraph::Arc Arc; |
---|
| 1230 | typedef typename Digraph::Node Node; |
---|
[244] | 1231 | void start(const Node&) {} |
---|
| 1232 | void reach(const Node&) {} |
---|
| 1233 | void process(const Node&) {} |
---|
[100] | 1234 | void discover(const Arc&) {} |
---|
| 1235 | void examine(const Arc&) {} |
---|
| 1236 | |
---|
| 1237 | template <typename _Visitor> |
---|
| 1238 | struct Constraints { |
---|
| 1239 | void constraints() { |
---|
[209] | 1240 | Arc arc; |
---|
| 1241 | Node node; |
---|
[244] | 1242 | visitor.start(node); |
---|
| 1243 | visitor.reach(node); |
---|
| 1244 | visitor.process(node); |
---|
[209] | 1245 | visitor.discover(arc); |
---|
| 1246 | visitor.examine(arc); |
---|
[100] | 1247 | } |
---|
| 1248 | _Visitor& visitor; |
---|
| 1249 | }; |
---|
| 1250 | }; |
---|
| 1251 | #endif |
---|
| 1252 | |
---|
| 1253 | /// \brief Default traits class of BfsVisit class. |
---|
| 1254 | /// |
---|
| 1255 | /// Default traits class of BfsVisit class. |
---|
[244] | 1256 | /// \tparam _Digraph The type of the digraph the algorithm runs on. |
---|
[100] | 1257 | template<class _Digraph> |
---|
| 1258 | struct BfsVisitDefaultTraits { |
---|
| 1259 | |
---|
[244] | 1260 | /// \brief The type of the digraph the algorithm runs on. |
---|
[100] | 1261 | typedef _Digraph Digraph; |
---|
| 1262 | |
---|
| 1263 | /// \brief The type of the map that indicates which nodes are reached. |
---|
[209] | 1264 | /// |
---|
[100] | 1265 | /// The type of the map that indicates which nodes are reached. |
---|
[244] | 1266 | /// It must meet the \ref concepts::ReadWriteMap "ReadWriteMap" concept. |
---|
[100] | 1267 | typedef typename Digraph::template NodeMap<bool> ReachedMap; |
---|
| 1268 | |
---|
[301] | 1269 | /// \brief Instantiates a ReachedMap. |
---|
[100] | 1270 | /// |
---|
[301] | 1271 | /// This function instantiates a ReachedMap. |
---|
[100] | 1272 | /// \param digraph is the digraph, to which |
---|
[301] | 1273 | /// we would like to define the ReachedMap. |
---|
[100] | 1274 | static ReachedMap *createReachedMap(const Digraph &digraph) { |
---|
| 1275 | return new ReachedMap(digraph); |
---|
| 1276 | } |
---|
| 1277 | |
---|
| 1278 | }; |
---|
| 1279 | |
---|
| 1280 | /// \ingroup search |
---|
[209] | 1281 | /// |
---|
[244] | 1282 | /// \brief %BFS algorithm class with visitor interface. |
---|
[209] | 1283 | /// |
---|
[100] | 1284 | /// This class provides an efficient implementation of the %BFS algorithm |
---|
| 1285 | /// with visitor interface. |
---|
| 1286 | /// |
---|
| 1287 | /// The %BfsVisit class provides an alternative interface to the Bfs |
---|
| 1288 | /// class. It works with callback mechanism, the BfsVisit object calls |
---|
[244] | 1289 | /// the member functions of the \c Visitor class on every BFS event. |
---|
[100] | 1290 | /// |
---|
[252] | 1291 | /// This interface of the BFS algorithm should be used in special cases |
---|
| 1292 | /// when extra actions have to be performed in connection with certain |
---|
| 1293 | /// events of the BFS algorithm. Otherwise consider to use Bfs or bfs() |
---|
| 1294 | /// instead. |
---|
| 1295 | /// |
---|
[244] | 1296 | /// \tparam _Digraph The type of the digraph the algorithm runs on. |
---|
[210] | 1297 | /// The default value is |
---|
[244] | 1298 | /// \ref ListDigraph. The value of _Digraph is not used directly by |
---|
| 1299 | /// \ref BfsVisit, it is only passed to \ref BfsVisitDefaultTraits. |
---|
| 1300 | /// \tparam _Visitor The Visitor type that is used by the algorithm. |
---|
| 1301 | /// \ref BfsVisitor "BfsVisitor<_Digraph>" is an empty visitor, which |
---|
| 1302 | /// does not observe the BFS events. If you want to observe the BFS |
---|
| 1303 | /// events, you should implement your own visitor class. |
---|
[209] | 1304 | /// \tparam _Traits Traits class to set various data types used by the |
---|
[100] | 1305 | /// algorithm. The default traits class is |
---|
| 1306 | /// \ref BfsVisitDefaultTraits "BfsVisitDefaultTraits<_Digraph>". |
---|
| 1307 | /// See \ref BfsVisitDefaultTraits for the documentation of |
---|
[244] | 1308 | /// a BFS visit traits class. |
---|
[100] | 1309 | #ifdef DOXYGEN |
---|
| 1310 | template <typename _Digraph, typename _Visitor, typename _Traits> |
---|
| 1311 | #else |
---|
| 1312 | template <typename _Digraph = ListDigraph, |
---|
[209] | 1313 | typename _Visitor = BfsVisitor<_Digraph>, |
---|
[288] | 1314 | typename _Traits = BfsVisitDefaultTraits<_Digraph> > |
---|
[100] | 1315 | #endif |
---|
| 1316 | class BfsVisit { |
---|
| 1317 | public: |
---|
[209] | 1318 | |
---|
[244] | 1319 | ///The traits class. |
---|
[100] | 1320 | typedef _Traits Traits; |
---|
| 1321 | |
---|
[244] | 1322 | ///The type of the digraph the algorithm runs on. |
---|
[100] | 1323 | typedef typename Traits::Digraph Digraph; |
---|
| 1324 | |
---|
[244] | 1325 | ///The visitor type used by the algorithm. |
---|
[100] | 1326 | typedef _Visitor Visitor; |
---|
| 1327 | |
---|
[244] | 1328 | ///The type of the map that indicates which nodes are reached. |
---|
[100] | 1329 | typedef typename Traits::ReachedMap ReachedMap; |
---|
| 1330 | |
---|
| 1331 | private: |
---|
| 1332 | |
---|
| 1333 | typedef typename Digraph::Node Node; |
---|
| 1334 | typedef typename Digraph::NodeIt NodeIt; |
---|
| 1335 | typedef typename Digraph::Arc Arc; |
---|
| 1336 | typedef typename Digraph::OutArcIt OutArcIt; |
---|
| 1337 | |
---|
[244] | 1338 | //Pointer to the underlying digraph. |
---|
[100] | 1339 | const Digraph *_digraph; |
---|
[244] | 1340 | //Pointer to the visitor object. |
---|
[100] | 1341 | Visitor *_visitor; |
---|
[244] | 1342 | //Pointer to the map of reached status of the nodes. |
---|
[100] | 1343 | ReachedMap *_reached; |
---|
[244] | 1344 | //Indicates if _reached is locally allocated (true) or not. |
---|
[100] | 1345 | bool local_reached; |
---|
| 1346 | |
---|
| 1347 | std::vector<typename Digraph::Node> _list; |
---|
| 1348 | int _list_front, _list_back; |
---|
| 1349 | |
---|
[280] | 1350 | //Creates the maps if necessary. |
---|
[100] | 1351 | void create_maps() { |
---|
| 1352 | if(!_reached) { |
---|
[209] | 1353 | local_reached = true; |
---|
| 1354 | _reached = Traits::createReachedMap(*_digraph); |
---|
[100] | 1355 | } |
---|
| 1356 | } |
---|
| 1357 | |
---|
| 1358 | protected: |
---|
| 1359 | |
---|
| 1360 | BfsVisit() {} |
---|
[209] | 1361 | |
---|
[100] | 1362 | public: |
---|
| 1363 | |
---|
| 1364 | typedef BfsVisit Create; |
---|
| 1365 | |
---|
| 1366 | /// \name Named template parameters |
---|
| 1367 | |
---|
| 1368 | ///@{ |
---|
| 1369 | template <class T> |
---|
[257] | 1370 | struct SetReachedMapTraits : public Traits { |
---|
[100] | 1371 | typedef T ReachedMap; |
---|
| 1372 | static ReachedMap *createReachedMap(const Digraph &digraph) { |
---|
[290] | 1373 | LEMON_ASSERT(false, "ReachedMap is not initialized"); |
---|
| 1374 | return 0; // ignore warnings |
---|
[100] | 1375 | } |
---|
| 1376 | }; |
---|
[209] | 1377 | /// \brief \ref named-templ-param "Named parameter" for setting |
---|
[244] | 1378 | /// ReachedMap type. |
---|
[100] | 1379 | /// |
---|
[244] | 1380 | /// \ref named-templ-param "Named parameter" for setting ReachedMap type. |
---|
[100] | 1381 | template <class T> |
---|
[257] | 1382 | struct SetReachedMap : public BfsVisit< Digraph, Visitor, |
---|
| 1383 | SetReachedMapTraits<T> > { |
---|
| 1384 | typedef BfsVisit< Digraph, Visitor, SetReachedMapTraits<T> > Create; |
---|
[100] | 1385 | }; |
---|
| 1386 | ///@} |
---|
| 1387 | |
---|
[209] | 1388 | public: |
---|
| 1389 | |
---|
[100] | 1390 | /// \brief Constructor. |
---|
| 1391 | /// |
---|
| 1392 | /// Constructor. |
---|
| 1393 | /// |
---|
[244] | 1394 | /// \param digraph The digraph the algorithm runs on. |
---|
| 1395 | /// \param visitor The visitor object of the algorithm. |
---|
[209] | 1396 | BfsVisit(const Digraph& digraph, Visitor& visitor) |
---|
[100] | 1397 | : _digraph(&digraph), _visitor(&visitor), |
---|
[209] | 1398 | _reached(0), local_reached(false) {} |
---|
| 1399 | |
---|
[100] | 1400 | /// \brief Destructor. |
---|
| 1401 | ~BfsVisit() { |
---|
| 1402 | if(local_reached) delete _reached; |
---|
| 1403 | } |
---|
| 1404 | |
---|
[244] | 1405 | /// \brief Sets the map that indicates which nodes are reached. |
---|
[100] | 1406 | /// |
---|
[244] | 1407 | /// Sets the map that indicates which nodes are reached. |
---|
[100] | 1408 | /// If you don't use this function before calling \ref run(), |
---|
[244] | 1409 | /// it will allocate one. The destructor deallocates this |
---|
[100] | 1410 | /// automatically allocated map, of course. |
---|
| 1411 | /// \return <tt> (*this) </tt> |
---|
| 1412 | BfsVisit &reachedMap(ReachedMap &m) { |
---|
| 1413 | if(local_reached) { |
---|
[209] | 1414 | delete _reached; |
---|
| 1415 | local_reached = false; |
---|
[100] | 1416 | } |
---|
| 1417 | _reached = &m; |
---|
| 1418 | return *this; |
---|
| 1419 | } |
---|
| 1420 | |
---|
| 1421 | public: |
---|
[244] | 1422 | |
---|
[100] | 1423 | /// \name Execution control |
---|
| 1424 | /// The simplest way to execute the algorithm is to use |
---|
[244] | 1425 | /// one of the member functions called \ref lemon::BfsVisit::run() |
---|
| 1426 | /// "run()". |
---|
[100] | 1427 | /// \n |
---|
[244] | 1428 | /// If you need more control on the execution, first you must call |
---|
| 1429 | /// \ref lemon::BfsVisit::init() "init()", then you can add several |
---|
| 1430 | /// source nodes with \ref lemon::BfsVisit::addSource() "addSource()". |
---|
| 1431 | /// Finally \ref lemon::BfsVisit::start() "start()" will perform the |
---|
| 1432 | /// actual path computation. |
---|
[100] | 1433 | |
---|
| 1434 | /// @{ |
---|
[244] | 1435 | |
---|
[100] | 1436 | /// \brief Initializes the internal data structures. |
---|
| 1437 | /// |
---|
| 1438 | /// Initializes the internal data structures. |
---|
| 1439 | void init() { |
---|
| 1440 | create_maps(); |
---|
| 1441 | _list.resize(countNodes(*_digraph)); |
---|
| 1442 | _list_front = _list_back = -1; |
---|
| 1443 | for (NodeIt u(*_digraph) ; u != INVALID ; ++u) { |
---|
[209] | 1444 | _reached->set(u, false); |
---|
[100] | 1445 | } |
---|
| 1446 | } |
---|
[209] | 1447 | |
---|
[100] | 1448 | /// \brief Adds a new source node. |
---|
| 1449 | /// |
---|
| 1450 | /// Adds a new source node to the set of nodes to be processed. |
---|
| 1451 | void addSource(Node s) { |
---|
| 1452 | if(!(*_reached)[s]) { |
---|
[209] | 1453 | _reached->set(s,true); |
---|
| 1454 | _visitor->start(s); |
---|
| 1455 | _visitor->reach(s); |
---|
[100] | 1456 | _list[++_list_back] = s; |
---|
[209] | 1457 | } |
---|
[100] | 1458 | } |
---|
[209] | 1459 | |
---|
[100] | 1460 | /// \brief Processes the next node. |
---|
| 1461 | /// |
---|
| 1462 | /// Processes the next node. |
---|
| 1463 | /// |
---|
| 1464 | /// \return The processed node. |
---|
| 1465 | /// |
---|
[244] | 1466 | /// \pre The queue must not be empty. |
---|
[209] | 1467 | Node processNextNode() { |
---|
[100] | 1468 | Node n = _list[++_list_front]; |
---|
| 1469 | _visitor->process(n); |
---|
| 1470 | Arc e; |
---|
| 1471 | for (_digraph->firstOut(e, n); e != INVALID; _digraph->nextOut(e)) { |
---|
| 1472 | Node m = _digraph->target(e); |
---|
| 1473 | if (!(*_reached)[m]) { |
---|
| 1474 | _visitor->discover(e); |
---|
| 1475 | _visitor->reach(m); |
---|
| 1476 | _reached->set(m, true); |
---|
| 1477 | _list[++_list_back] = m; |
---|
| 1478 | } else { |
---|
| 1479 | _visitor->examine(e); |
---|
| 1480 | } |
---|
| 1481 | } |
---|
| 1482 | return n; |
---|
| 1483 | } |
---|
| 1484 | |
---|
| 1485 | /// \brief Processes the next node. |
---|
| 1486 | /// |
---|
[244] | 1487 | /// Processes the next node and checks if the given target node |
---|
[100] | 1488 | /// is reached. If the target node is reachable from the processed |
---|
[244] | 1489 | /// node, then the \c reach parameter will be set to \c true. |
---|
[100] | 1490 | /// |
---|
| 1491 | /// \param target The target node. |
---|
[244] | 1492 | /// \retval reach Indicates if the target node is reached. |
---|
| 1493 | /// It should be initially \c false. |
---|
| 1494 | /// |
---|
[100] | 1495 | /// \return The processed node. |
---|
| 1496 | /// |
---|
[244] | 1497 | /// \pre The queue must not be empty. |
---|
[100] | 1498 | Node processNextNode(Node target, bool& reach) { |
---|
| 1499 | Node n = _list[++_list_front]; |
---|
| 1500 | _visitor->process(n); |
---|
| 1501 | Arc e; |
---|
| 1502 | for (_digraph->firstOut(e, n); e != INVALID; _digraph->nextOut(e)) { |
---|
| 1503 | Node m = _digraph->target(e); |
---|
| 1504 | if (!(*_reached)[m]) { |
---|
| 1505 | _visitor->discover(e); |
---|
| 1506 | _visitor->reach(m); |
---|
| 1507 | _reached->set(m, true); |
---|
| 1508 | _list[++_list_back] = m; |
---|
| 1509 | reach = reach || (target == m); |
---|
| 1510 | } else { |
---|
| 1511 | _visitor->examine(e); |
---|
| 1512 | } |
---|
| 1513 | } |
---|
| 1514 | return n; |
---|
| 1515 | } |
---|
| 1516 | |
---|
| 1517 | /// \brief Processes the next node. |
---|
| 1518 | /// |
---|
[244] | 1519 | /// Processes the next node and checks if at least one of reached |
---|
| 1520 | /// nodes has \c true value in the \c nm node map. If one node |
---|
| 1521 | /// with \c true value is reachable from the processed node, then the |
---|
| 1522 | /// \c rnode parameter will be set to the first of such nodes. |
---|
[100] | 1523 | /// |
---|
[244] | 1524 | /// \param nm A \c bool (or convertible) node map that indicates the |
---|
| 1525 | /// possible targets. |
---|
[100] | 1526 | /// \retval rnode The reached target node. |
---|
[244] | 1527 | /// It should be initially \c INVALID. |
---|
| 1528 | /// |
---|
[100] | 1529 | /// \return The processed node. |
---|
| 1530 | /// |
---|
[244] | 1531 | /// \pre The queue must not be empty. |
---|
[100] | 1532 | template <typename NM> |
---|
| 1533 | Node processNextNode(const NM& nm, Node& rnode) { |
---|
| 1534 | Node n = _list[++_list_front]; |
---|
| 1535 | _visitor->process(n); |
---|
| 1536 | Arc e; |
---|
| 1537 | for (_digraph->firstOut(e, n); e != INVALID; _digraph->nextOut(e)) { |
---|
| 1538 | Node m = _digraph->target(e); |
---|
| 1539 | if (!(*_reached)[m]) { |
---|
| 1540 | _visitor->discover(e); |
---|
| 1541 | _visitor->reach(m); |
---|
| 1542 | _reached->set(m, true); |
---|
| 1543 | _list[++_list_back] = m; |
---|
| 1544 | if (nm[m] && rnode == INVALID) rnode = m; |
---|
| 1545 | } else { |
---|
| 1546 | _visitor->examine(e); |
---|
| 1547 | } |
---|
| 1548 | } |
---|
| 1549 | return n; |
---|
| 1550 | } |
---|
| 1551 | |
---|
[244] | 1552 | /// \brief The next node to be processed. |
---|
[100] | 1553 | /// |
---|
[244] | 1554 | /// Returns the next node to be processed or \c INVALID if the queue |
---|
| 1555 | /// is empty. |
---|
| 1556 | Node nextNode() const { |
---|
[100] | 1557 | return _list_front != _list_back ? _list[_list_front + 1] : INVALID; |
---|
| 1558 | } |
---|
| 1559 | |
---|
| 1560 | /// \brief Returns \c false if there are nodes |
---|
[244] | 1561 | /// to be processed. |
---|
[100] | 1562 | /// |
---|
| 1563 | /// Returns \c false if there are nodes |
---|
[244] | 1564 | /// to be processed in the queue. |
---|
| 1565 | bool emptyQueue() const { return _list_front == _list_back; } |
---|
[100] | 1566 | |
---|
| 1567 | /// \brief Returns the number of the nodes to be processed. |
---|
| 1568 | /// |
---|
| 1569 | /// Returns the number of the nodes to be processed in the queue. |
---|
[244] | 1570 | int queueSize() const { return _list_back - _list_front; } |
---|
[209] | 1571 | |
---|
[100] | 1572 | /// \brief Executes the algorithm. |
---|
| 1573 | /// |
---|
| 1574 | /// Executes the algorithm. |
---|
| 1575 | /// |
---|
[244] | 1576 | /// This method runs the %BFS algorithm from the root node(s) |
---|
| 1577 | /// in order to compute the shortest path to each node. |
---|
| 1578 | /// |
---|
| 1579 | /// The algorithm computes |
---|
| 1580 | /// - the shortest path tree (forest), |
---|
| 1581 | /// - the distance of each node from the root(s). |
---|
| 1582 | /// |
---|
| 1583 | /// \pre init() must be called and at least one root node should be added |
---|
[100] | 1584 | /// with addSource() before using this function. |
---|
[244] | 1585 | /// |
---|
| 1586 | /// \note <tt>b.start()</tt> is just a shortcut of the following code. |
---|
| 1587 | /// \code |
---|
| 1588 | /// while ( !b.emptyQueue() ) { |
---|
| 1589 | /// b.processNextNode(); |
---|
| 1590 | /// } |
---|
| 1591 | /// \endcode |
---|
[100] | 1592 | void start() { |
---|
| 1593 | while ( !emptyQueue() ) processNextNode(); |
---|
| 1594 | } |
---|
[209] | 1595 | |
---|
[244] | 1596 | /// \brief Executes the algorithm until the given target node is reached. |
---|
[100] | 1597 | /// |
---|
[244] | 1598 | /// Executes the algorithm until the given target node is reached. |
---|
[100] | 1599 | /// |
---|
[244] | 1600 | /// This method runs the %BFS algorithm from the root node(s) |
---|
[286] | 1601 | /// in order to compute the shortest path to \c t. |
---|
[244] | 1602 | /// |
---|
| 1603 | /// The algorithm computes |
---|
[286] | 1604 | /// - the shortest path to \c t, |
---|
| 1605 | /// - the distance of \c t from the root(s). |
---|
[244] | 1606 | /// |
---|
| 1607 | /// \pre init() must be called and at least one root node should be |
---|
| 1608 | /// added with addSource() before using this function. |
---|
| 1609 | /// |
---|
| 1610 | /// \note <tt>b.start(t)</tt> is just a shortcut of the following code. |
---|
| 1611 | /// \code |
---|
| 1612 | /// bool reach = false; |
---|
| 1613 | /// while ( !b.emptyQueue() && !reach ) { |
---|
| 1614 | /// b.processNextNode(t, reach); |
---|
| 1615 | /// } |
---|
| 1616 | /// \endcode |
---|
[286] | 1617 | void start(Node t) { |
---|
[100] | 1618 | bool reach = false; |
---|
[286] | 1619 | while ( !emptyQueue() && !reach ) processNextNode(t, reach); |
---|
[100] | 1620 | } |
---|
[209] | 1621 | |
---|
[100] | 1622 | /// \brief Executes the algorithm until a condition is met. |
---|
| 1623 | /// |
---|
| 1624 | /// Executes the algorithm until a condition is met. |
---|
| 1625 | /// |
---|
[244] | 1626 | /// This method runs the %BFS algorithm from the root node(s) in |
---|
| 1627 | /// order to compute the shortest path to a node \c v with |
---|
| 1628 | /// <tt>nm[v]</tt> true, if such a node can be found. |
---|
[100] | 1629 | /// |
---|
[244] | 1630 | /// \param nm must be a bool (or convertible) node map. The |
---|
| 1631 | /// algorithm will stop when it reaches a node \c v with |
---|
[100] | 1632 | /// <tt>nm[v]</tt> true. |
---|
| 1633 | /// |
---|
[244] | 1634 | /// \return The reached node \c v with <tt>nm[v]</tt> true or |
---|
| 1635 | /// \c INVALID if no such node was found. |
---|
| 1636 | /// |
---|
| 1637 | /// \pre init() must be called and at least one root node should be |
---|
| 1638 | /// added with addSource() before using this function. |
---|
| 1639 | /// |
---|
| 1640 | /// \note <tt>b.start(nm)</tt> is just a shortcut of the following code. |
---|
| 1641 | /// \code |
---|
| 1642 | /// Node rnode = INVALID; |
---|
| 1643 | /// while ( !b.emptyQueue() && rnode == INVALID ) { |
---|
| 1644 | /// b.processNextNode(nm, rnode); |
---|
| 1645 | /// } |
---|
| 1646 | /// return rnode; |
---|
| 1647 | /// \endcode |
---|
[100] | 1648 | template <typename NM> |
---|
| 1649 | Node start(const NM &nm) { |
---|
| 1650 | Node rnode = INVALID; |
---|
| 1651 | while ( !emptyQueue() && rnode == INVALID ) { |
---|
[209] | 1652 | processNextNode(nm, rnode); |
---|
[100] | 1653 | } |
---|
| 1654 | return rnode; |
---|
| 1655 | } |
---|
| 1656 | |
---|
[286] | 1657 | /// \brief Runs the algorithm from the given source node. |
---|
[100] | 1658 | /// |
---|
[244] | 1659 | /// This method runs the %BFS algorithm from node \c s |
---|
| 1660 | /// in order to compute the shortest path to each node. |
---|
| 1661 | /// |
---|
| 1662 | /// The algorithm computes |
---|
| 1663 | /// - the shortest path tree, |
---|
| 1664 | /// - the distance of each node from the root. |
---|
| 1665 | /// |
---|
| 1666 | /// \note <tt>b.run(s)</tt> is just a shortcut of the following code. |
---|
[100] | 1667 | ///\code |
---|
| 1668 | /// b.init(); |
---|
| 1669 | /// b.addSource(s); |
---|
| 1670 | /// b.start(); |
---|
| 1671 | ///\endcode |
---|
| 1672 | void run(Node s) { |
---|
| 1673 | init(); |
---|
| 1674 | addSource(s); |
---|
| 1675 | start(); |
---|
| 1676 | } |
---|
| 1677 | |
---|
[286] | 1678 | /// \brief Finds the shortest path between \c s and \c t. |
---|
| 1679 | /// |
---|
| 1680 | /// This method runs the %BFS algorithm from node \c s |
---|
| 1681 | /// in order to compute the shortest path to node \c t |
---|
| 1682 | /// (it stops searching when \c t is processed). |
---|
| 1683 | /// |
---|
| 1684 | /// \return \c true if \c t is reachable form \c s. |
---|
| 1685 | /// |
---|
| 1686 | /// \note Apart from the return value, <tt>b.run(s,t)</tt> is just a |
---|
| 1687 | /// shortcut of the following code. |
---|
| 1688 | ///\code |
---|
| 1689 | /// b.init(); |
---|
| 1690 | /// b.addSource(s); |
---|
| 1691 | /// b.start(t); |
---|
| 1692 | ///\endcode |
---|
| 1693 | bool run(Node s,Node t) { |
---|
| 1694 | init(); |
---|
| 1695 | addSource(s); |
---|
| 1696 | start(t); |
---|
| 1697 | return reached(t); |
---|
| 1698 | } |
---|
| 1699 | |
---|
[244] | 1700 | /// \brief Runs the algorithm to visit all nodes in the digraph. |
---|
[209] | 1701 | /// |
---|
[100] | 1702 | /// This method runs the %BFS algorithm in order to |
---|
[244] | 1703 | /// compute the shortest path to each node. |
---|
[100] | 1704 | /// |
---|
[244] | 1705 | /// The algorithm computes |
---|
| 1706 | /// - the shortest path tree (forest), |
---|
| 1707 | /// - the distance of each node from the root(s). |
---|
| 1708 | /// |
---|
| 1709 | /// \note <tt>b.run(s)</tt> is just a shortcut of the following code. |
---|
[100] | 1710 | ///\code |
---|
| 1711 | /// b.init(); |
---|
[244] | 1712 | /// for (NodeIt n(gr); n != INVALID; ++n) { |
---|
| 1713 | /// if (!b.reached(n)) { |
---|
| 1714 | /// b.addSource(n); |
---|
[100] | 1715 | /// b.start(); |
---|
| 1716 | /// } |
---|
| 1717 | /// } |
---|
| 1718 | ///\endcode |
---|
| 1719 | void run() { |
---|
| 1720 | init(); |
---|
| 1721 | for (NodeIt it(*_digraph); it != INVALID; ++it) { |
---|
| 1722 | if (!reached(it)) { |
---|
| 1723 | addSource(it); |
---|
| 1724 | start(); |
---|
| 1725 | } |
---|
| 1726 | } |
---|
| 1727 | } |
---|
[244] | 1728 | |
---|
[100] | 1729 | ///@} |
---|
| 1730 | |
---|
| 1731 | /// \name Query Functions |
---|
| 1732 | /// The result of the %BFS algorithm can be obtained using these |
---|
| 1733 | /// functions.\n |
---|
[244] | 1734 | /// Either \ref lemon::BfsVisit::run() "run()" or |
---|
| 1735 | /// \ref lemon::BfsVisit::start() "start()" must be called before |
---|
| 1736 | /// using them. |
---|
[100] | 1737 | ///@{ |
---|
| 1738 | |
---|
[244] | 1739 | /// \brief Checks if a node is reachable from the root(s). |
---|
[100] | 1740 | /// |
---|
| 1741 | /// Returns \c true if \c v is reachable from the root(s). |
---|
| 1742 | /// \pre Either \ref run() or \ref start() |
---|
| 1743 | /// must be called before using this function. |
---|
| 1744 | bool reached(Node v) { return (*_reached)[v]; } |
---|
[244] | 1745 | |
---|
[100] | 1746 | ///@} |
---|
[244] | 1747 | |
---|
[100] | 1748 | }; |
---|
| 1749 | |
---|
| 1750 | } //END OF NAMESPACE LEMON |
---|
| 1751 | |
---|
| 1752 | #endif |
---|