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