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