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