1 | /* -*- C++ -*- |
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2 | * |
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3 | * This file is a part of LEMON, a generic C++ optimization library |
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4 | * |
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5 | * Copyright (C) 2003-2006 |
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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 flowalgs |
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23 | ///\file |
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24 | ///\brief Bfs algorithm. |
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25 | |
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26 | #include <lemon/list_graph.h> |
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27 | #include <lemon/graph_utils.h> |
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28 | #include <lemon/bits/invalid.h> |
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29 | #include <lemon/error.h> |
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30 | #include <lemon/maps.h> |
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31 | |
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32 | namespace lemon { |
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33 | |
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34 | |
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35 | |
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36 | ///Default traits class of Bfs class. |
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37 | |
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38 | ///Default traits class of Bfs class. |
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39 | ///\param GR Graph type. |
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40 | template<class GR> |
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41 | struct BfsDefaultTraits |
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42 | { |
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43 | ///The graph type the algorithm runs on. |
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44 | typedef GR Graph; |
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45 | ///\brief The type of the map that stores the last |
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46 | ///edges of the shortest paths. |
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47 | /// |
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48 | ///The type of the map that stores the last |
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49 | ///edges of the shortest paths. |
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50 | ///It must meet the \ref concepts::WriteMap "WriteMap" concept. |
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51 | /// |
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52 | typedef typename Graph::template NodeMap<typename GR::Edge> PredMap; |
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53 | ///Instantiates a PredMap. |
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54 | |
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55 | ///This function instantiates a \ref PredMap. |
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56 | ///\param G is the graph, to which we would like to define the PredMap. |
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57 | ///\todo The graph alone may be insufficient to initialize |
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58 | static PredMap *createPredMap(const GR &G) |
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59 | { |
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60 | return new PredMap(G); |
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61 | } |
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62 | ///The type of the map that indicates which nodes are processed. |
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63 | |
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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 | ///\todo named parameter to set this type, function to read and write. |
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67 | typedef NullMap<typename Graph::Node,bool> ProcessedMap; |
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68 | ///Instantiates a ProcessedMap. |
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69 | |
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70 | ///This function instantiates a \ref ProcessedMap. |
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71 | ///\param g is the graph, to which |
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72 | ///we would like to define the \ref ProcessedMap |
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73 | #ifdef DOXYGEN |
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74 | static ProcessedMap *createProcessedMap(const GR &g) |
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75 | #else |
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76 | static ProcessedMap *createProcessedMap(const GR &) |
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77 | #endif |
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78 | { |
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79 | return new ProcessedMap(); |
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80 | } |
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81 | ///The type of the map that indicates which nodes are reached. |
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82 | |
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83 | ///The type of the map that indicates which nodes are reached. |
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84 | ///It must meet the \ref concepts::WriteMap "WriteMap" concept. |
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85 | ///\todo named parameter to set this type, function to read and write. |
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86 | typedef typename Graph::template NodeMap<bool> ReachedMap; |
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87 | ///Instantiates a ReachedMap. |
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88 | |
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89 | ///This function instantiates a \ref ReachedMap. |
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90 | ///\param G is the graph, to which |
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91 | ///we would like to define the \ref ReachedMap. |
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92 | static ReachedMap *createReachedMap(const GR &G) |
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93 | { |
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94 | return new ReachedMap(G); |
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95 | } |
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96 | ///The type of the map that stores the dists of the nodes. |
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97 | |
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98 | ///The type of the map that stores the dists of the nodes. |
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99 | ///It must meet the \ref concepts::WriteMap "WriteMap" concept. |
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100 | /// |
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101 | typedef typename Graph::template NodeMap<int> DistMap; |
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102 | ///Instantiates a DistMap. |
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103 | |
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104 | ///This function instantiates a \ref DistMap. |
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105 | ///\param G is the graph, to which we would like to define the \ref DistMap |
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106 | static DistMap *createDistMap(const GR &G) |
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107 | { |
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108 | return new DistMap(G); |
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109 | } |
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110 | }; |
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111 | |
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112 | ///%BFS algorithm class. |
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113 | |
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114 | ///\ingroup flowalgs |
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115 | ///This class provides an efficient implementation of the %BFS algorithm. |
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116 | /// |
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117 | ///\param GR The graph type the algorithm runs on. The default value is |
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118 | ///\ref ListGraph. The value of GR is not used directly by Bfs, it |
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119 | ///is only passed to \ref BfsDefaultTraits. |
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120 | ///\param TR Traits class to set various data types used by the algorithm. |
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121 | ///The default traits class is |
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122 | ///\ref BfsDefaultTraits "BfsDefaultTraits<GR>". |
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123 | ///See \ref BfsDefaultTraits for the documentation of |
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124 | ///a Bfs traits class. |
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125 | /// |
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126 | ///\author Alpar Juttner |
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127 | |
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128 | #ifdef DOXYGEN |
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129 | template <typename GR, |
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130 | typename TR> |
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131 | #else |
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132 | template <typename GR=ListGraph, |
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133 | typename TR=BfsDefaultTraits<GR> > |
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134 | #endif |
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135 | class Bfs { |
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136 | public: |
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137 | /** |
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138 | * \brief \ref Exception for uninitialized parameters. |
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139 | * |
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140 | * This error represents problems in the initialization |
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141 | * of the parameters of the algorithms. |
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142 | */ |
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143 | class UninitializedParameter : public lemon::UninitializedParameter { |
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144 | public: |
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145 | virtual const char* what() const throw() { |
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146 | return "lemon::Bfs::UninitializedParameter"; |
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147 | } |
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148 | }; |
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149 | |
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150 | typedef TR Traits; |
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151 | ///The type of the underlying graph. |
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152 | typedef typename TR::Graph Graph; |
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153 | ///\e |
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154 | typedef typename Graph::Node Node; |
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155 | ///\e |
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156 | typedef typename Graph::NodeIt NodeIt; |
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157 | ///\e |
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158 | typedef typename Graph::Edge Edge; |
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159 | ///\e |
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160 | typedef typename Graph::OutEdgeIt OutEdgeIt; |
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161 | |
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162 | ///\brief The type of the map that stores the last |
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163 | ///edges of the shortest paths. |
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164 | typedef typename TR::PredMap PredMap; |
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165 | ///The type of the map indicating which nodes are reached. |
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166 | typedef typename TR::ReachedMap ReachedMap; |
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167 | ///The type of the map indicating which nodes are processed. |
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168 | typedef typename TR::ProcessedMap ProcessedMap; |
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169 | ///The type of the map that stores the dists of the nodes. |
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170 | typedef typename TR::DistMap DistMap; |
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171 | private: |
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172 | /// Pointer to the underlying graph. |
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173 | const Graph *G; |
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174 | ///Pointer to the map of predecessors edges. |
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175 | PredMap *_pred; |
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176 | ///Indicates if \ref _pred is locally allocated (\c true) or not. |
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177 | bool local_pred; |
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178 | ///Pointer to the map of distances. |
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179 | DistMap *_dist; |
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180 | ///Indicates if \ref _dist is locally allocated (\c true) or not. |
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181 | bool local_dist; |
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182 | ///Pointer to the map of reached status of the nodes. |
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183 | ReachedMap *_reached; |
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184 | ///Indicates if \ref _reached is locally allocated (\c true) or not. |
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185 | bool local_reached; |
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186 | ///Pointer to the map of processed status of the nodes. |
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187 | ProcessedMap *_processed; |
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188 | ///Indicates if \ref _processed is locally allocated (\c true) or not. |
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189 | bool local_processed; |
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190 | |
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191 | std::vector<typename Graph::Node> _queue; |
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192 | int _queue_head,_queue_tail,_queue_next_dist; |
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193 | int _curr_dist; |
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194 | |
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195 | ///Creates the maps if necessary. |
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196 | |
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197 | ///\todo Better memory allocation (instead of new). |
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198 | void create_maps() |
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199 | { |
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200 | if(!_pred) { |
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201 | local_pred = true; |
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202 | _pred = Traits::createPredMap(*G); |
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203 | } |
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204 | if(!_dist) { |
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205 | local_dist = true; |
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206 | _dist = Traits::createDistMap(*G); |
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207 | } |
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208 | if(!_reached) { |
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209 | local_reached = true; |
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210 | _reached = Traits::createReachedMap(*G); |
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211 | } |
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212 | if(!_processed) { |
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213 | local_processed = true; |
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214 | _processed = Traits::createProcessedMap(*G); |
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215 | } |
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216 | } |
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217 | |
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218 | protected: |
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219 | |
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220 | Bfs() {} |
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221 | |
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222 | public: |
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223 | |
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224 | typedef Bfs Create; |
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225 | |
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226 | ///\name Named template parameters |
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227 | |
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228 | ///@{ |
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229 | |
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230 | template <class T> |
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231 | struct DefPredMapTraits : public Traits { |
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232 | typedef T PredMap; |
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233 | static PredMap *createPredMap(const Graph &) |
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234 | { |
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235 | throw UninitializedParameter(); |
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236 | } |
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237 | }; |
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238 | ///\ref named-templ-param "Named parameter" for setting PredMap type |
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239 | |
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240 | ///\ref named-templ-param "Named parameter" for setting PredMap type |
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241 | /// |
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242 | template <class T> |
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243 | struct DefPredMap : public Bfs< Graph, DefPredMapTraits<T> > { |
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244 | typedef Bfs< Graph, DefPredMapTraits<T> > Create; |
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245 | }; |
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246 | |
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247 | template <class T> |
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248 | struct DefDistMapTraits : public Traits { |
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249 | typedef T DistMap; |
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250 | static DistMap *createDistMap(const Graph &) |
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251 | { |
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252 | throw UninitializedParameter(); |
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253 | } |
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254 | }; |
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255 | ///\ref named-templ-param "Named parameter" for setting DistMap type |
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256 | |
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257 | ///\ref named-templ-param "Named parameter" for setting DistMap type |
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258 | /// |
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259 | template <class T> |
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260 | struct DefDistMap : public Bfs< Graph, DefDistMapTraits<T> > { |
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261 | typedef Bfs< Graph, DefDistMapTraits<T> > Create; |
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262 | }; |
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263 | |
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264 | template <class T> |
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265 | struct DefReachedMapTraits : public Traits { |
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266 | typedef T ReachedMap; |
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267 | static ReachedMap *createReachedMap(const Graph &) |
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268 | { |
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269 | throw UninitializedParameter(); |
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270 | } |
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271 | }; |
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272 | ///\ref named-templ-param "Named parameter" for setting ReachedMap type |
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273 | |
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274 | ///\ref named-templ-param "Named parameter" for setting ReachedMap type |
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275 | /// |
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276 | template <class T> |
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277 | struct DefReachedMap : public Bfs< Graph, DefReachedMapTraits<T> > { |
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278 | typedef Bfs< Graph, DefReachedMapTraits<T> > Create; |
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279 | }; |
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280 | |
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281 | template <class T> |
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282 | struct DefProcessedMapTraits : public Traits { |
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283 | typedef T ProcessedMap; |
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284 | static ProcessedMap *createProcessedMap(const Graph &) |
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285 | { |
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286 | throw UninitializedParameter(); |
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287 | } |
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288 | }; |
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289 | ///\ref named-templ-param "Named parameter" for setting ProcessedMap type |
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290 | |
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291 | ///\ref named-templ-param "Named parameter" for setting ProcessedMap type |
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292 | /// |
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293 | template <class T> |
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294 | struct DefProcessedMap : public Bfs< Graph, DefProcessedMapTraits<T> > { |
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295 | typedef Bfs< Graph, DefProcessedMapTraits<T> > Create; |
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296 | }; |
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297 | |
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298 | struct DefGraphProcessedMapTraits : public Traits { |
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299 | typedef typename Graph::template NodeMap<bool> ProcessedMap; |
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300 | static ProcessedMap *createProcessedMap(const Graph &G) |
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301 | { |
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302 | return new ProcessedMap(G); |
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303 | } |
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304 | }; |
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305 | ///\brief \ref named-templ-param "Named parameter" |
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306 | ///for setting the ProcessedMap type to be Graph::NodeMap<bool>. |
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307 | /// |
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308 | ///\ref named-templ-param "Named parameter" |
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309 | ///for setting the ProcessedMap type to be Graph::NodeMap<bool>. |
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310 | ///If you don't set it explicitly, it will be automatically allocated. |
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311 | template <class T> |
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312 | struct DefProcessedMapToBeDefaultMap : |
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313 | public Bfs< Graph, DefGraphProcessedMapTraits> { |
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314 | typedef Bfs< Graph, DefGraphProcessedMapTraits> Create; |
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315 | }; |
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316 | |
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317 | ///@} |
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318 | |
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319 | public: |
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320 | |
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321 | ///Constructor. |
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322 | |
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323 | ///\param _G the graph the algorithm will run on. |
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324 | /// |
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325 | Bfs(const Graph& _G) : |
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326 | G(&_G), |
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327 | _pred(NULL), local_pred(false), |
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328 | _dist(NULL), local_dist(false), |
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329 | _reached(NULL), local_reached(false), |
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330 | _processed(NULL), local_processed(false) |
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331 | { } |
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332 | |
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333 | ///Destructor. |
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334 | ~Bfs() |
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335 | { |
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336 | if(local_pred) delete _pred; |
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337 | if(local_dist) delete _dist; |
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338 | if(local_reached) delete _reached; |
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339 | if(local_processed) delete _processed; |
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340 | } |
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341 | |
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342 | ///Sets the map storing the predecessor edges. |
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343 | |
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344 | ///Sets the map storing the predecessor edges. |
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345 | ///If you don't use this function before calling \ref run(), |
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346 | ///it will allocate one. The destructor deallocates this |
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347 | ///automatically allocated map, of course. |
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348 | ///\return <tt> (*this) </tt> |
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349 | Bfs &predMap(PredMap &m) |
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350 | { |
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351 | if(local_pred) { |
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352 | delete _pred; |
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353 | local_pred=false; |
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354 | } |
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355 | _pred = &m; |
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356 | return *this; |
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357 | } |
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358 | |
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359 | ///Sets the map indicating the reached nodes. |
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360 | |
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361 | ///Sets the map indicating the reached nodes. |
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362 | ///If you don't use this function before calling \ref run(), |
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363 | ///it will allocate one. The destructor deallocates this |
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364 | ///automatically allocated map, of course. |
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365 | ///\return <tt> (*this) </tt> |
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366 | Bfs &reachedMap(ReachedMap &m) |
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367 | { |
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368 | if(local_reached) { |
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369 | delete _reached; |
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370 | local_reached=false; |
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371 | } |
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372 | _reached = &m; |
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373 | return *this; |
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374 | } |
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375 | |
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376 | ///Sets the map indicating the processed nodes. |
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377 | |
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378 | ///Sets the map indicating the processed nodes. |
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379 | ///If you don't use this function before calling \ref run(), |
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380 | ///it will allocate one. The destructor deallocates this |
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381 | ///automatically allocated map, of course. |
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382 | ///\return <tt> (*this) </tt> |
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383 | Bfs &processedMap(ProcessedMap &m) |
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384 | { |
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385 | if(local_processed) { |
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386 | delete _processed; |
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387 | local_processed=false; |
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388 | } |
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389 | _processed = &m; |
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390 | return *this; |
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391 | } |
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392 | |
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393 | ///Sets the map storing the distances calculated by the algorithm. |
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394 | |
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395 | ///Sets the map storing the distances calculated by the algorithm. |
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396 | ///If you don't use this function before calling \ref run(), |
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397 | ///it will allocate one. The destructor deallocates this |
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398 | ///automatically allocated map, of course. |
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399 | ///\return <tt> (*this) </tt> |
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400 | Bfs &distMap(DistMap &m) |
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401 | { |
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402 | if(local_dist) { |
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403 | delete _dist; |
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404 | local_dist=false; |
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405 | } |
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406 | _dist = &m; |
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407 | return *this; |
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408 | } |
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409 | |
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410 | public: |
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411 | ///\name Execution control |
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412 | ///The simplest way to execute the algorithm is to use |
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413 | ///one of the member functions called \c run(...). |
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414 | ///\n |
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415 | ///If you need more control on the execution, |
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416 | ///first you must call \ref init(), then you can add several source nodes |
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417 | ///with \ref addSource(). |
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418 | ///Finally \ref start() will perform the actual path |
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419 | ///computation. |
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420 | |
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421 | ///@{ |
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422 | |
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423 | ///Initializes the internal data structures. |
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424 | |
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425 | ///Initializes the internal data structures. |
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426 | /// |
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427 | void init() |
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428 | { |
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429 | create_maps(); |
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430 | _queue.resize(countNodes(*G)); |
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431 | _queue_head=_queue_tail=0; |
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432 | _curr_dist=1; |
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433 | for ( NodeIt u(*G) ; u!=INVALID ; ++u ) { |
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434 | _pred->set(u,INVALID); |
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435 | _reached->set(u,false); |
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436 | _processed->set(u,false); |
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437 | } |
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438 | } |
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439 | |
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440 | ///Adds a new source node. |
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441 | |
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442 | ///Adds a new source node to the set of nodes to be processed. |
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443 | /// |
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444 | void addSource(Node s) |
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445 | { |
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446 | if(!(*_reached)[s]) |
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447 | { |
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448 | _reached->set(s,true); |
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449 | _pred->set(s,INVALID); |
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450 | _dist->set(s,0); |
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451 | _queue[_queue_head++]=s; |
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452 | _queue_next_dist=_queue_head; |
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453 | } |
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454 | } |
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455 | |
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456 | ///Processes the next node. |
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457 | |
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458 | ///Processes the next node. |
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459 | /// |
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460 | ///\return The processed node. |
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461 | /// |
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462 | ///\warning The queue must not be empty! |
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463 | Node processNextNode() |
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464 | { |
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465 | if(_queue_tail==_queue_next_dist) { |
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466 | _curr_dist++; |
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467 | _queue_next_dist=_queue_head; |
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468 | } |
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469 | Node n=_queue[_queue_tail++]; |
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470 | _processed->set(n,true); |
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471 | Node m; |
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472 | for(OutEdgeIt e(*G,n);e!=INVALID;++e) |
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473 | if(!(*_reached)[m=G->target(e)]) { |
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474 | _queue[_queue_head++]=m; |
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475 | _reached->set(m,true); |
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476 | _pred->set(m,e); |
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477 | _dist->set(m,_curr_dist); |
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478 | } |
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479 | return n; |
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480 | } |
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481 | |
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482 | ///Processes the next node. |
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483 | |
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484 | ///Processes the next node. And checks that the given target node |
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485 | ///is reached. If the target node is reachable from the processed |
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486 | ///node then the reached parameter will be set true. The reached |
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487 | ///parameter should be initially false. |
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488 | /// |
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489 | ///\param target The target node. |
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490 | ///\retval reached Indicates that the target node is reached. |
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491 | ///\return The processed node. |
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492 | /// |
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493 | ///\warning The queue must not be empty! |
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494 | Node processNextNode(Node target, bool& reached) |
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495 | { |
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496 | if(_queue_tail==_queue_next_dist) { |
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497 | _curr_dist++; |
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498 | _queue_next_dist=_queue_head; |
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499 | } |
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500 | Node n=_queue[_queue_tail++]; |
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501 | _processed->set(n,true); |
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502 | Node m; |
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503 | for(OutEdgeIt e(*G,n);e!=INVALID;++e) |
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504 | if(!(*_reached)[m=G->target(e)]) { |
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505 | _queue[_queue_head++]=m; |
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506 | _reached->set(m,true); |
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507 | _pred->set(m,e); |
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508 | _dist->set(m,_curr_dist); |
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509 | reached = reached || (target == m); |
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510 | } |
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511 | return n; |
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512 | } |
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513 | |
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514 | ///Processes the next node. |
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515 | |
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516 | ///Processes the next node. And checks that at least one of |
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517 | ///reached node has true value in the \c nm nodemap. If one node |
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518 | ///with true value is reachable from the processed node then the |
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519 | ///reached parameter will be set true. The reached parameter |
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520 | ///should be initially false. |
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521 | /// |
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522 | ///\param target The nodemaps of possible targets. |
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523 | ///\retval reached Indicates that one of the target nodes is reached. |
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524 | ///\return The processed node. |
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525 | /// |
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526 | ///\warning The queue must not be empty! |
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527 | template<class NM> |
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528 | Node processNextNode(const NM& nm, bool& reached) |
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529 | { |
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530 | if(_queue_tail==_queue_next_dist) { |
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531 | _curr_dist++; |
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532 | _queue_next_dist=_queue_head; |
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533 | } |
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534 | Node n=_queue[_queue_tail++]; |
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535 | _processed->set(n,true); |
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536 | Node m; |
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537 | for(OutEdgeIt e(*G,n);e!=INVALID;++e) |
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538 | if(!(*_reached)[m=G->target(e)]) { |
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539 | _queue[_queue_head++]=m; |
---|
540 | _reached->set(m,true); |
---|
541 | _pred->set(m,e); |
---|
542 | _dist->set(m,_curr_dist); |
---|
543 | reached = reached || nm[m]; |
---|
544 | } |
---|
545 | return n; |
---|
546 | } |
---|
547 | |
---|
548 | ///Next node to be processed. |
---|
549 | |
---|
550 | ///Next node to be processed. |
---|
551 | /// |
---|
552 | ///\return The next node to be processed or INVALID if the queue is |
---|
553 | /// empty. |
---|
554 | Node nextNode() |
---|
555 | { |
---|
556 | return _queue_tail<_queue_head?_queue[_queue_tail]:INVALID; |
---|
557 | } |
---|
558 | |
---|
559 | ///\brief Returns \c false if there are nodes |
---|
560 | ///to be processed in the queue |
---|
561 | /// |
---|
562 | ///Returns \c false if there are nodes |
---|
563 | ///to be processed in the queue |
---|
564 | bool emptyQueue() { return _queue_tail==_queue_head; } |
---|
565 | ///Returns the number of the nodes to be processed. |
---|
566 | |
---|
567 | ///Returns the number of the nodes to be processed in the queue. |
---|
568 | /// |
---|
569 | int queueSize() { return _queue_head-_queue_tail; } |
---|
570 | |
---|
571 | ///Executes the algorithm. |
---|
572 | |
---|
573 | ///Executes the algorithm. |
---|
574 | /// |
---|
575 | ///\pre init() must be called and at least one node should be added |
---|
576 | ///with addSource() before using this function. |
---|
577 | /// |
---|
578 | ///This method runs the %BFS algorithm from the root node(s) |
---|
579 | ///in order to |
---|
580 | ///compute the |
---|
581 | ///shortest path to each node. The algorithm computes |
---|
582 | ///- The shortest path tree. |
---|
583 | ///- The distance of each node from the root(s). |
---|
584 | /// |
---|
585 | void start() |
---|
586 | { |
---|
587 | while ( !emptyQueue() ) processNextNode(); |
---|
588 | } |
---|
589 | |
---|
590 | ///Executes the algorithm until \c dest is reached. |
---|
591 | |
---|
592 | ///Executes the algorithm until \c dest is reached. |
---|
593 | /// |
---|
594 | ///\pre init() must be called and at least one node should be added |
---|
595 | ///with addSource() before using this function. |
---|
596 | /// |
---|
597 | ///This method runs the %BFS algorithm from the root node(s) |
---|
598 | ///in order to |
---|
599 | ///compute the |
---|
600 | ///shortest path to \c dest. The algorithm computes |
---|
601 | ///- The shortest path to \c dest. |
---|
602 | ///- The distance of \c dest from the root(s). |
---|
603 | /// |
---|
604 | void start(Node dest) |
---|
605 | { |
---|
606 | bool reached = false; |
---|
607 | while ( !emptyQueue() && !reached) processNextNode(dest, reached); |
---|
608 | } |
---|
609 | |
---|
610 | ///Executes the algorithm until a condition is met. |
---|
611 | |
---|
612 | ///Executes the algorithm until a condition is met. |
---|
613 | /// |
---|
614 | ///\pre init() must be called and at least one node should be added |
---|
615 | ///with addSource() before using this function. |
---|
616 | /// |
---|
617 | ///\param nm must be a bool (or convertible) node map. The algorithm |
---|
618 | ///will stop when it reaches a node \c v with <tt>nm[v]==true</tt>. |
---|
619 | ///\todo query the reached target |
---|
620 | template<class NM> |
---|
621 | void start(const NM &nm) |
---|
622 | { |
---|
623 | bool reached = false; |
---|
624 | while ( !emptyQueue() && !reached) processNextNode(nm, reached); |
---|
625 | } |
---|
626 | |
---|
627 | ///Runs %BFS algorithm from node \c s. |
---|
628 | |
---|
629 | ///This method runs the %BFS algorithm from a root node \c s |
---|
630 | ///in order to |
---|
631 | ///compute the |
---|
632 | ///shortest path to each node. The algorithm computes |
---|
633 | ///- The shortest path tree. |
---|
634 | ///- The distance of each node from the root. |
---|
635 | /// |
---|
636 | ///\note d.run(s) is just a shortcut of the following code. |
---|
637 | ///\code |
---|
638 | /// d.init(); |
---|
639 | /// d.addSource(s); |
---|
640 | /// d.start(); |
---|
641 | ///\endcode |
---|
642 | void run(Node s) { |
---|
643 | init(); |
---|
644 | addSource(s); |
---|
645 | start(); |
---|
646 | } |
---|
647 | |
---|
648 | ///Finds the shortest path between \c s and \c t. |
---|
649 | |
---|
650 | ///Finds the shortest path between \c s and \c t. |
---|
651 | /// |
---|
652 | ///\return The length of the shortest s---t path if there exists one, |
---|
653 | ///0 otherwise. |
---|
654 | ///\note Apart from the return value, d.run(s) is |
---|
655 | ///just a shortcut of the following code. |
---|
656 | ///\code |
---|
657 | /// d.init(); |
---|
658 | /// d.addSource(s); |
---|
659 | /// d.start(t); |
---|
660 | ///\endcode |
---|
661 | int run(Node s,Node t) { |
---|
662 | init(); |
---|
663 | addSource(s); |
---|
664 | start(t); |
---|
665 | return reached(t)? _curr_dist : 0; |
---|
666 | } |
---|
667 | |
---|
668 | ///@} |
---|
669 | |
---|
670 | ///\name Query Functions |
---|
671 | ///The result of the %BFS algorithm can be obtained using these |
---|
672 | ///functions.\n |
---|
673 | ///Before the use of these functions, |
---|
674 | ///either run() or start() must be called. |
---|
675 | |
---|
676 | ///@{ |
---|
677 | |
---|
678 | ///Copies the shortest path to \c t into \c p |
---|
679 | |
---|
680 | ///This function copies the shortest path to \c t into \c p. |
---|
681 | ///If \c t is a source itself or unreachable, then it does not |
---|
682 | ///alter \c p. |
---|
683 | ///\return Returns \c true if a path to \c t was actually copied to \c p, |
---|
684 | ///\c false otherwise. |
---|
685 | ///\sa DirPath |
---|
686 | template<class P> |
---|
687 | bool getPath(P &p,Node t) |
---|
688 | { |
---|
689 | if(reached(t)) { |
---|
690 | p.clear(); |
---|
691 | typename P::Builder b(p); |
---|
692 | for(b.setStartNode(t);predEdge(t)!=INVALID;t=predNode(t)) |
---|
693 | b.pushFront(predEdge(t)); |
---|
694 | b.commit(); |
---|
695 | return true; |
---|
696 | } |
---|
697 | return false; |
---|
698 | } |
---|
699 | |
---|
700 | ///The distance of a node from the root(s). |
---|
701 | |
---|
702 | ///Returns the distance of a node from the root(s). |
---|
703 | ///\pre \ref run() must be called before using this function. |
---|
704 | ///\warning If node \c v in unreachable from the root(s) the return value |
---|
705 | ///of this function is undefined. |
---|
706 | int dist(Node v) const { return (*_dist)[v]; } |
---|
707 | |
---|
708 | ///Returns the 'previous edge' of the shortest path tree. |
---|
709 | |
---|
710 | ///For a node \c v it returns the 'previous edge' |
---|
711 | ///of the shortest path tree, |
---|
712 | ///i.e. it returns the last edge of a shortest path from the root(s) to \c |
---|
713 | ///v. It is \ref INVALID |
---|
714 | ///if \c v is unreachable from the root(s) or \c v is a root. The |
---|
715 | ///shortest path tree used here is equal to the shortest path tree used in |
---|
716 | ///\ref predNode(). |
---|
717 | ///\pre Either \ref run() or \ref start() must be called before using |
---|
718 | ///this function. |
---|
719 | Edge predEdge(Node v) const { return (*_pred)[v];} |
---|
720 | |
---|
721 | ///Returns the 'previous node' of the shortest path tree. |
---|
722 | |
---|
723 | ///For a node \c v it returns the 'previous node' |
---|
724 | ///of the shortest path tree, |
---|
725 | ///i.e. it returns the last but one node from a shortest path from the |
---|
726 | ///root(a) to \c /v. |
---|
727 | ///It is INVALID if \c v is unreachable from the root(s) or |
---|
728 | ///if \c v itself a root. |
---|
729 | ///The shortest path tree used here is equal to the shortest path |
---|
730 | ///tree used in \ref predEdge(). |
---|
731 | ///\pre Either \ref run() or \ref start() must be called before |
---|
732 | ///using this function. |
---|
733 | Node predNode(Node v) const { return (*_pred)[v]==INVALID ? INVALID: |
---|
734 | G->source((*_pred)[v]); } |
---|
735 | |
---|
736 | ///Returns a reference to the NodeMap of distances. |
---|
737 | |
---|
738 | ///Returns a reference to the NodeMap of distances. |
---|
739 | ///\pre Either \ref run() or \ref init() must |
---|
740 | ///be called before using this function. |
---|
741 | const DistMap &distMap() const { return *_dist;} |
---|
742 | |
---|
743 | ///Returns a reference to the shortest path tree map. |
---|
744 | |
---|
745 | ///Returns a reference to the NodeMap of the edges of the |
---|
746 | ///shortest path tree. |
---|
747 | ///\pre Either \ref run() or \ref init() |
---|
748 | ///must be called before using this function. |
---|
749 | const PredMap &predMap() const { return *_pred;} |
---|
750 | |
---|
751 | ///Checks if a node is reachable from the root. |
---|
752 | |
---|
753 | ///Returns \c true if \c v is reachable from the root. |
---|
754 | ///\warning The source nodes are indicated as unreached. |
---|
755 | ///\pre Either \ref run() or \ref start() |
---|
756 | ///must be called before using this function. |
---|
757 | /// |
---|
758 | bool reached(Node v) { return (*_reached)[v]; } |
---|
759 | |
---|
760 | ///@} |
---|
761 | }; |
---|
762 | |
---|
763 | ///Default traits class of Bfs function. |
---|
764 | |
---|
765 | ///Default traits class of Bfs function. |
---|
766 | ///\param GR Graph type. |
---|
767 | template<class GR> |
---|
768 | struct BfsWizardDefaultTraits |
---|
769 | { |
---|
770 | ///The graph type the algorithm runs on. |
---|
771 | typedef GR Graph; |
---|
772 | ///\brief The type of the map that stores the last |
---|
773 | ///edges of the shortest paths. |
---|
774 | /// |
---|
775 | ///The type of the map that stores the last |
---|
776 | ///edges of the shortest paths. |
---|
777 | ///It must meet the \ref concepts::WriteMap "WriteMap" concept. |
---|
778 | /// |
---|
779 | typedef NullMap<typename Graph::Node,typename GR::Edge> PredMap; |
---|
780 | ///Instantiates a PredMap. |
---|
781 | |
---|
782 | ///This function instantiates a \ref PredMap. |
---|
783 | ///\param g is the graph, to which we would like to define the PredMap. |
---|
784 | ///\todo The graph alone may be insufficient to initialize |
---|
785 | #ifdef DOXYGEN |
---|
786 | static PredMap *createPredMap(const GR &g) |
---|
787 | #else |
---|
788 | static PredMap *createPredMap(const GR &) |
---|
789 | #endif |
---|
790 | { |
---|
791 | return new PredMap(); |
---|
792 | } |
---|
793 | |
---|
794 | ///The type of the map that indicates which nodes are processed. |
---|
795 | |
---|
796 | ///The type of the map that indicates which nodes are processed. |
---|
797 | ///It must meet the \ref concepts::WriteMap "WriteMap" concept. |
---|
798 | ///\todo named parameter to set this type, function to read and write. |
---|
799 | typedef NullMap<typename Graph::Node,bool> ProcessedMap; |
---|
800 | ///Instantiates a ProcessedMap. |
---|
801 | |
---|
802 | ///This function instantiates a \ref ProcessedMap. |
---|
803 | ///\param g is the graph, to which |
---|
804 | ///we would like to define the \ref ProcessedMap |
---|
805 | #ifdef DOXYGEN |
---|
806 | static ProcessedMap *createProcessedMap(const GR &g) |
---|
807 | #else |
---|
808 | static ProcessedMap *createProcessedMap(const GR &) |
---|
809 | #endif |
---|
810 | { |
---|
811 | return new ProcessedMap(); |
---|
812 | } |
---|
813 | ///The type of the map that indicates which nodes are reached. |
---|
814 | |
---|
815 | ///The type of the map that indicates which nodes are reached. |
---|
816 | ///It must meet the \ref concepts::WriteMap "WriteMap" concept. |
---|
817 | ///\todo named parameter to set this type, function to read and write. |
---|
818 | typedef typename Graph::template NodeMap<bool> ReachedMap; |
---|
819 | ///Instantiates a ReachedMap. |
---|
820 | |
---|
821 | ///This function instantiates a \ref ReachedMap. |
---|
822 | ///\param G is the graph, to which |
---|
823 | ///we would like to define the \ref ReachedMap. |
---|
824 | static ReachedMap *createReachedMap(const GR &G) |
---|
825 | { |
---|
826 | return new ReachedMap(G); |
---|
827 | } |
---|
828 | ///The type of the map that stores the dists of the nodes. |
---|
829 | |
---|
830 | ///The type of the map that stores the dists of the nodes. |
---|
831 | ///It must meet the \ref concepts::WriteMap "WriteMap" concept. |
---|
832 | /// |
---|
833 | typedef NullMap<typename Graph::Node,int> DistMap; |
---|
834 | ///Instantiates a DistMap. |
---|
835 | |
---|
836 | ///This function instantiates a \ref DistMap. |
---|
837 | ///\param g is the graph, to which we would like to define the \ref DistMap |
---|
838 | #ifdef DOXYGEN |
---|
839 | static DistMap *createDistMap(const GR &g) |
---|
840 | #else |
---|
841 | static DistMap *createDistMap(const GR &) |
---|
842 | #endif |
---|
843 | { |
---|
844 | return new DistMap(); |
---|
845 | } |
---|
846 | }; |
---|
847 | |
---|
848 | /// Default traits used by \ref BfsWizard |
---|
849 | |
---|
850 | /// To make it easier to use Bfs algorithm |
---|
851 | ///we have created a wizard class. |
---|
852 | /// This \ref BfsWizard class needs default traits, |
---|
853 | ///as well as the \ref Bfs class. |
---|
854 | /// The \ref BfsWizardBase is a class to be the default traits of the |
---|
855 | /// \ref BfsWizard class. |
---|
856 | template<class GR> |
---|
857 | class BfsWizardBase : public BfsWizardDefaultTraits<GR> |
---|
858 | { |
---|
859 | |
---|
860 | typedef BfsWizardDefaultTraits<GR> Base; |
---|
861 | protected: |
---|
862 | /// Type of the nodes in the graph. |
---|
863 | typedef typename Base::Graph::Node Node; |
---|
864 | |
---|
865 | /// Pointer to the underlying graph. |
---|
866 | void *_g; |
---|
867 | ///Pointer to the map of reached nodes. |
---|
868 | void *_reached; |
---|
869 | ///Pointer to the map of processed nodes. |
---|
870 | void *_processed; |
---|
871 | ///Pointer to the map of predecessors edges. |
---|
872 | void *_pred; |
---|
873 | ///Pointer to the map of distances. |
---|
874 | void *_dist; |
---|
875 | ///Pointer to the source node. |
---|
876 | Node _source; |
---|
877 | |
---|
878 | public: |
---|
879 | /// Constructor. |
---|
880 | |
---|
881 | /// This constructor does not require parameters, therefore it initiates |
---|
882 | /// all of the attributes to default values (0, INVALID). |
---|
883 | BfsWizardBase() : _g(0), _reached(0), _processed(0), _pred(0), |
---|
884 | _dist(0), _source(INVALID) {} |
---|
885 | |
---|
886 | /// Constructor. |
---|
887 | |
---|
888 | /// This constructor requires some parameters, |
---|
889 | /// listed in the parameters list. |
---|
890 | /// Others are initiated to 0. |
---|
891 | /// \param g is the initial value of \ref _g |
---|
892 | /// \param s is the initial value of \ref _source |
---|
893 | BfsWizardBase(const GR &g, Node s=INVALID) : |
---|
894 | _g((void *)&g), _reached(0), _processed(0), _pred(0), |
---|
895 | _dist(0), _source(s) {} |
---|
896 | |
---|
897 | }; |
---|
898 | |
---|
899 | /// A class to make the usage of Bfs algorithm easier |
---|
900 | |
---|
901 | /// This class is created to make it easier to use Bfs algorithm. |
---|
902 | /// It uses the functions and features of the plain \ref Bfs, |
---|
903 | /// but it is much simpler to use it. |
---|
904 | /// |
---|
905 | /// Simplicity means that the way to change the types defined |
---|
906 | /// in the traits class is based on functions that returns the new class |
---|
907 | /// and not on templatable built-in classes. |
---|
908 | /// When using the plain \ref Bfs |
---|
909 | /// the new class with the modified type comes from |
---|
910 | /// the original class by using the :: |
---|
911 | /// operator. In the case of \ref BfsWizard only |
---|
912 | /// a function have to be called and it will |
---|
913 | /// return the needed class. |
---|
914 | /// |
---|
915 | /// It does not have own \ref run method. When its \ref run method is called |
---|
916 | /// it initiates a plain \ref Bfs class, and calls the \ref Bfs::run |
---|
917 | /// method of it. |
---|
918 | template<class TR> |
---|
919 | class BfsWizard : public TR |
---|
920 | { |
---|
921 | typedef TR Base; |
---|
922 | |
---|
923 | ///The type of the underlying graph. |
---|
924 | typedef typename TR::Graph Graph; |
---|
925 | //\e |
---|
926 | typedef typename Graph::Node Node; |
---|
927 | //\e |
---|
928 | typedef typename Graph::NodeIt NodeIt; |
---|
929 | //\e |
---|
930 | typedef typename Graph::Edge Edge; |
---|
931 | //\e |
---|
932 | typedef typename Graph::OutEdgeIt OutEdgeIt; |
---|
933 | |
---|
934 | ///\brief The type of the map that stores |
---|
935 | ///the reached nodes |
---|
936 | typedef typename TR::ReachedMap ReachedMap; |
---|
937 | ///\brief The type of the map that stores |
---|
938 | ///the processed nodes |
---|
939 | typedef typename TR::ProcessedMap ProcessedMap; |
---|
940 | ///\brief The type of the map that stores the last |
---|
941 | ///edges of the shortest paths. |
---|
942 | typedef typename TR::PredMap PredMap; |
---|
943 | ///The type of the map that stores the dists of the nodes. |
---|
944 | typedef typename TR::DistMap DistMap; |
---|
945 | |
---|
946 | public: |
---|
947 | /// Constructor. |
---|
948 | BfsWizard() : TR() {} |
---|
949 | |
---|
950 | /// Constructor that requires parameters. |
---|
951 | |
---|
952 | /// Constructor that requires parameters. |
---|
953 | /// These parameters will be the default values for the traits class. |
---|
954 | BfsWizard(const Graph &g, Node s=INVALID) : |
---|
955 | TR(g,s) {} |
---|
956 | |
---|
957 | ///Copy constructor |
---|
958 | BfsWizard(const TR &b) : TR(b) {} |
---|
959 | |
---|
960 | ~BfsWizard() {} |
---|
961 | |
---|
962 | ///Runs Bfs algorithm from a given node. |
---|
963 | |
---|
964 | ///Runs Bfs algorithm from a given node. |
---|
965 | ///The node can be given by the \ref source function. |
---|
966 | void run() |
---|
967 | { |
---|
968 | if(Base::_source==INVALID) throw UninitializedParameter(); |
---|
969 | Bfs<Graph,TR> alg(*(Graph*)Base::_g); |
---|
970 | if(Base::_reached) |
---|
971 | alg.reachedMap(*(ReachedMap*)Base::_reached); |
---|
972 | if(Base::_processed) alg.processedMap(*(ProcessedMap*)Base::_processed); |
---|
973 | if(Base::_pred) alg.predMap(*(PredMap*)Base::_pred); |
---|
974 | if(Base::_dist) alg.distMap(*(DistMap*)Base::_dist); |
---|
975 | alg.run(Base::_source); |
---|
976 | } |
---|
977 | |
---|
978 | ///Runs Bfs algorithm from the given node. |
---|
979 | |
---|
980 | ///Runs Bfs algorithm from the given node. |
---|
981 | ///\param s is the given source. |
---|
982 | void run(Node s) |
---|
983 | { |
---|
984 | Base::_source=s; |
---|
985 | run(); |
---|
986 | } |
---|
987 | |
---|
988 | template<class T> |
---|
989 | struct DefPredMapBase : public Base { |
---|
990 | typedef T PredMap; |
---|
991 | static PredMap *createPredMap(const Graph &) { return 0; }; |
---|
992 | DefPredMapBase(const TR &b) : TR(b) {} |
---|
993 | }; |
---|
994 | |
---|
995 | ///\brief \ref named-templ-param "Named parameter" |
---|
996 | ///function for setting PredMap |
---|
997 | /// |
---|
998 | /// \ref named-templ-param "Named parameter" |
---|
999 | ///function for setting PredMap |
---|
1000 | /// |
---|
1001 | template<class T> |
---|
1002 | BfsWizard<DefPredMapBase<T> > predMap(const T &t) |
---|
1003 | { |
---|
1004 | Base::_pred=(void *)&t; |
---|
1005 | return BfsWizard<DefPredMapBase<T> >(*this); |
---|
1006 | } |
---|
1007 | |
---|
1008 | |
---|
1009 | template<class T> |
---|
1010 | struct DefReachedMapBase : public Base { |
---|
1011 | typedef T ReachedMap; |
---|
1012 | static ReachedMap *createReachedMap(const Graph &) { return 0; }; |
---|
1013 | DefReachedMapBase(const TR &b) : TR(b) {} |
---|
1014 | }; |
---|
1015 | |
---|
1016 | ///\brief \ref named-templ-param "Named parameter" |
---|
1017 | ///function for setting ReachedMap |
---|
1018 | /// |
---|
1019 | /// \ref named-templ-param "Named parameter" |
---|
1020 | ///function for setting ReachedMap |
---|
1021 | /// |
---|
1022 | template<class T> |
---|
1023 | BfsWizard<DefReachedMapBase<T> > reachedMap(const T &t) |
---|
1024 | { |
---|
1025 | Base::_pred=(void *)&t; |
---|
1026 | return BfsWizard<DefReachedMapBase<T> >(*this); |
---|
1027 | } |
---|
1028 | |
---|
1029 | |
---|
1030 | template<class T> |
---|
1031 | struct DefProcessedMapBase : public Base { |
---|
1032 | typedef T ProcessedMap; |
---|
1033 | static ProcessedMap *createProcessedMap(const Graph &) { return 0; }; |
---|
1034 | DefProcessedMapBase(const TR &b) : TR(b) {} |
---|
1035 | }; |
---|
1036 | |
---|
1037 | ///\brief \ref named-templ-param "Named parameter" |
---|
1038 | ///function for setting ProcessedMap |
---|
1039 | /// |
---|
1040 | /// \ref named-templ-param "Named parameter" |
---|
1041 | ///function for setting ProcessedMap |
---|
1042 | /// |
---|
1043 | template<class T> |
---|
1044 | BfsWizard<DefProcessedMapBase<T> > processedMap(const T &t) |
---|
1045 | { |
---|
1046 | Base::_pred=(void *)&t; |
---|
1047 | return BfsWizard<DefProcessedMapBase<T> >(*this); |
---|
1048 | } |
---|
1049 | |
---|
1050 | |
---|
1051 | template<class T> |
---|
1052 | struct DefDistMapBase : public Base { |
---|
1053 | typedef T DistMap; |
---|
1054 | static DistMap *createDistMap(const Graph &) { return 0; }; |
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1055 | DefDistMapBase(const TR &b) : TR(b) {} |
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1056 | }; |
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1057 | |
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1058 | ///\brief \ref named-templ-param "Named parameter" |
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1059 | ///function for setting DistMap type |
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1060 | /// |
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1061 | /// \ref named-templ-param "Named parameter" |
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1062 | ///function for setting DistMap type |
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1063 | /// |
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1064 | template<class T> |
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1065 | BfsWizard<DefDistMapBase<T> > distMap(const T &t) |
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1066 | { |
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1067 | Base::_dist=(void *)&t; |
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1068 | return BfsWizard<DefDistMapBase<T> >(*this); |
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1069 | } |
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1070 | |
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1071 | /// Sets the source node, from which the Bfs algorithm runs. |
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1072 | |
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1073 | /// Sets the source node, from which the Bfs algorithm runs. |
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1074 | /// \param s is the source node. |
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1075 | BfsWizard<TR> &source(Node s) |
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1076 | { |
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1077 | Base::_source=s; |
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1078 | return *this; |
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1079 | } |
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1080 | |
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1081 | }; |
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1082 | |
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1083 | ///Function type interface for Bfs algorithm. |
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1084 | |
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1085 | /// \ingroup flowalgs |
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1086 | ///Function type interface for Bfs algorithm. |
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1087 | /// |
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1088 | ///This function also has several |
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1089 | ///\ref named-templ-func-param "named parameters", |
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1090 | ///they are declared as the members of class \ref BfsWizard. |
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1091 | ///The following |
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1092 | ///example shows how to use these parameters. |
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1093 | ///\code |
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1094 | /// bfs(g,source).predMap(preds).run(); |
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1095 | ///\endcode |
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1096 | ///\warning Don't forget to put the \ref BfsWizard::run() "run()" |
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1097 | ///to the end of the parameter list. |
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1098 | ///\sa BfsWizard |
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1099 | ///\sa Bfs |
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1100 | template<class GR> |
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1101 | BfsWizard<BfsWizardBase<GR> > |
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1102 | bfs(const GR &g,typename GR::Node s=INVALID) |
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1103 | { |
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1104 | return BfsWizard<BfsWizardBase<GR> >(g,s); |
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1105 | } |
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1106 | |
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1107 | } //END OF NAMESPACE LEMON |
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1108 | |
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1109 | #endif |
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1110 | |
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