1 | /* -*- C++ -*- |
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2 | * src/lemon/dijkstra.h - Part of LEMON, a generic C++ optimization library |
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3 | * |
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4 | * Copyright (C) 2005 Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport |
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5 | * (Egervary Combinatorial Optimization Research Group, EGRES). |
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6 | * |
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7 | * Permission to use, modify and distribute this software is granted |
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8 | * provided that this copyright notice appears in all copies. For |
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9 | * precise terms see the accompanying LICENSE file. |
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10 | * |
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11 | * This software is provided "AS IS" with no warranty of any kind, |
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12 | * express or implied, and with no claim as to its suitability for any |
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13 | * purpose. |
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14 | * |
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15 | */ |
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16 | |
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17 | #ifndef LEMON_DIJKSTRA_H |
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18 | #define LEMON_DIJKSTRA_H |
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19 | |
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20 | ///\ingroup flowalgs |
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21 | ///\file |
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22 | ///\brief Dijkstra algorithm. |
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23 | |
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24 | #include <lemon/list_graph.h> |
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25 | #include <lemon/bin_heap.h> |
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26 | #include <lemon/invalid.h> |
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27 | #include <lemon/error.h> |
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28 | #include <lemon/maps.h> |
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29 | |
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30 | namespace lemon { |
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31 | |
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32 | |
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33 | |
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34 | ///Default traits class of Dijkstra class. |
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35 | |
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36 | ///Default traits class of Dijkstra class. |
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37 | ///\param GR Graph type. |
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38 | ///\param LM Type of length map. |
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39 | template<class GR, class LM> |
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40 | struct DijkstraDefaultTraits |
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41 | { |
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42 | ///The graph type the algorithm runs on. |
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43 | typedef GR Graph; |
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44 | ///The type of the map that stores the edge lengths. |
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45 | |
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46 | ///The type of the map that stores the edge lengths. |
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47 | ///It must meet the \ref concept::ReadMap "ReadMap" concept. |
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48 | typedef LM LengthMap; |
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49 | //The type of the length of the edges. |
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50 | typedef typename LM::Value Value; |
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51 | ///The heap type used by Dijkstra algorithm. |
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52 | |
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53 | ///The heap type used by Dijkstra algorithm. |
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54 | /// |
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55 | ///\sa BinHeap |
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56 | ///\sa Dijkstra |
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57 | typedef BinHeap<typename Graph::Node, |
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58 | typename LM::Value, |
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59 | typename GR::template NodeMap<int>, |
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60 | std::less<Value> > Heap; |
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61 | |
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62 | ///\brief The type of the map that stores the last |
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63 | ///edges of the shortest paths. |
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64 | /// |
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65 | ///The type of the map that stores the last |
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66 | ///edges of the shortest paths. |
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67 | ///It must meet the \ref concept::WriteMap "WriteMap" concept. |
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68 | /// |
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69 | typedef typename Graph::template NodeMap<typename GR::Edge> PredMap; |
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70 | ///Instantiates a PredMap. |
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71 | |
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72 | ///This function instantiates a \ref PredMap. |
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73 | ///\param G is the graph, to which we would like to define the PredMap. |
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74 | ///\todo The graph alone may be insufficient for the initialization |
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75 | static PredMap *createPredMap(const GR &G) |
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76 | { |
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77 | return new PredMap(G); |
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78 | } |
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79 | ///\brief The type of the map that stores the last but one |
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80 | ///nodes of the shortest paths. |
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81 | /// |
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82 | ///The type of the map that stores the last but one |
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83 | ///nodes of the shortest paths. |
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84 | ///It must meet the \ref concept::WriteMap "WriteMap" concept. |
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85 | /// |
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86 | typedef NullMap<typename Graph::Node,typename Graph::Node> PredNodeMap; |
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87 | ///Instantiates a PredNodeMap. |
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88 | |
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89 | ///This function instantiates a \ref PredNodeMap. |
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90 | ///\param G is the graph, to which |
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91 | ///we would like to define the \ref PredNodeMap |
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92 | static PredNodeMap *createPredNodeMap(const GR &G) |
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93 | { |
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94 | return new PredNodeMap(); |
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95 | } |
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96 | |
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97 | ///The type of the map that stores whether a nodes is reached. |
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98 | |
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99 | ///The type of the map that stores whether a nodes is reached. |
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100 | ///It must meet the \ref concept::WriteMap "WriteMap" concept. |
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101 | ///By default it is a NullMap. |
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102 | ///\todo If it is set to a real map, Dijkstra::reached() should read this. |
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103 | ///\todo named parameter to set this type, function to read and write. |
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104 | typedef NullMap<typename Graph::Node,bool> ReachedMap; |
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105 | ///Instantiates a ReachedMap. |
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106 | |
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107 | ///This function instantiates a \ref ReachedMap. |
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108 | ///\param G is the graph, to which |
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109 | ///we would like to define the \ref ReachedMap |
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110 | static ReachedMap *createReachedMap(const GR &G) |
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111 | { |
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112 | return new ReachedMap(); |
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113 | } |
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114 | ///The type of the map that stores the dists of the nodes. |
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115 | |
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116 | ///The type of the map that stores the dists of the nodes. |
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117 | ///It must meet the \ref concept::WriteMap "WriteMap" concept. |
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118 | /// |
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119 | typedef typename Graph::template NodeMap<typename LM::Value> DistMap; |
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120 | ///Instantiates a DistMap. |
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121 | |
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122 | ///This function instantiates a \ref DistMap. |
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123 | ///\param G is the graph, to which we would like to define the \ref DistMap |
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124 | static DistMap *createDistMap(const GR &G) |
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125 | { |
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126 | return new DistMap(G); |
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127 | } |
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128 | }; |
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129 | |
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130 | ///%Dijkstra algorithm class. |
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131 | |
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132 | /// \ingroup flowalgs |
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133 | ///This class provides an efficient implementation of %Dijkstra algorithm. |
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134 | ///The edge lengths are passed to the algorithm using a |
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135 | ///\ref concept::ReadMap "ReadMap", |
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136 | ///so it is easy to change it to any kind of length. |
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137 | /// |
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138 | ///The type of the length is determined by the |
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139 | ///\ref concept::ReadMap::Value "Value" of the length map. |
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140 | /// |
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141 | ///It is also possible to change the underlying priority heap. |
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142 | /// |
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143 | ///\param GR The graph type the algorithm runs on. The default value is |
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144 | ///\ref ListGraph. The value of GR is not used directly by Dijkstra, it |
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145 | ///is only passed to \ref DijkstraDefaultTraits. |
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146 | ///\param LM This read-only |
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147 | ///EdgeMap |
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148 | ///determines the |
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149 | ///lengths of the edges. It is read once for each edge, so the map |
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150 | ///may involve in relatively time consuming process to compute the edge |
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151 | ///length if it is necessary. The default map type is |
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152 | ///\ref concept::StaticGraph::EdgeMap "Graph::EdgeMap<int>". |
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153 | ///The value of LM is not used directly by Dijkstra, it |
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154 | ///is only passed to \ref DijkstraDefaultTraits. |
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155 | ///\param TR Traits class to set various data types used by the algorithm. |
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156 | ///The default traits class is |
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157 | ///\ref DijkstraDefaultTraits "DijkstraDefaultTraits<GR,LM>". |
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158 | ///See \ref DijkstraDefaultTraits for the documentation of |
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159 | ///a Dijkstra traits class. |
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160 | /// |
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161 | ///\author Jacint Szabo and Alpar Juttner |
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162 | ///\todo A compare object would be nice. |
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163 | |
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164 | #ifdef DOXYGEN |
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165 | template <typename GR, |
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166 | typename LM, |
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167 | typename TR> |
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168 | #else |
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169 | template <typename GR=ListGraph, |
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170 | typename LM=typename GR::template EdgeMap<int>, |
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171 | typename TR=DijkstraDefaultTraits<GR,LM> > |
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172 | #endif |
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173 | class Dijkstra { |
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174 | public: |
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175 | /** |
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176 | * \brief \ref Exception for uninitialized parameters. |
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177 | * |
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178 | * This error represents problems in the initialization |
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179 | * of the parameters of the algorithms. |
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180 | */ |
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181 | class UninitializedParameter : public lemon::UninitializedParameter { |
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182 | public: |
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183 | virtual const char* exceptionName() const { |
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184 | return "lemon::Dijsktra::UninitializedParameter"; |
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185 | } |
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186 | }; |
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187 | |
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188 | typedef TR Traits; |
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189 | ///The type of the underlying graph. |
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190 | typedef typename TR::Graph Graph; |
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191 | ///\e |
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192 | typedef typename Graph::Node Node; |
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193 | ///\e |
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194 | typedef typename Graph::NodeIt NodeIt; |
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195 | ///\e |
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196 | typedef typename Graph::Edge Edge; |
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197 | ///\e |
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198 | typedef typename Graph::OutEdgeIt OutEdgeIt; |
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199 | |
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200 | ///The type of the length of the edges. |
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201 | typedef typename TR::LengthMap::Value Value; |
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202 | ///The type of the map that stores the edge lengths. |
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203 | typedef typename TR::LengthMap LengthMap; |
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204 | ///\brief The type of the map that stores the last |
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205 | ///edges of the shortest paths. |
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206 | typedef typename TR::PredMap PredMap; |
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207 | ///\brief The type of the map that stores the last but one |
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208 | ///nodes of the shortest paths. |
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209 | typedef typename TR::PredNodeMap PredNodeMap; |
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210 | ///The type of the map indicating if a node is reached. |
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211 | typedef typename TR::ReachedMap ReachedMap; |
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212 | ///The type of the map that stores the dists of the nodes. |
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213 | typedef typename TR::DistMap DistMap; |
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214 | ///The heap type used by the dijkstra algorithm. |
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215 | typedef typename TR::Heap Heap; |
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216 | private: |
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217 | /// Pointer to the underlying graph. |
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218 | const Graph *G; |
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219 | /// Pointer to the length map |
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220 | const LengthMap *length; |
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221 | ///Pointer to the map of predecessors edges. |
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222 | PredMap *_pred; |
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223 | ///Indicates if \ref _pred is locally allocated (\c true) or not. |
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224 | bool local_pred; |
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225 | ///Pointer to the map of predecessors nodes. |
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226 | PredNodeMap *_predNode; |
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227 | ///Indicates if \ref _predNode is locally allocated (\c true) or not. |
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228 | bool local_predNode; |
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229 | ///Pointer to the map of distances. |
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230 | DistMap *_dist; |
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231 | ///Indicates if \ref _dist is locally allocated (\c true) or not. |
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232 | bool local_dist; |
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233 | ///Pointer to the map of reached status of the nodes. |
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234 | ReachedMap *_reached; |
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235 | ///Indicates if \ref _reached is locally allocated (\c true) or not. |
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236 | bool local_reached; |
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237 | |
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238 | ///The source node of the last execution. |
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239 | Node source; |
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240 | |
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241 | ///Creates the maps if necessary. |
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242 | |
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243 | ///\todo Error if \c G or are \c NULL. What about \c length? |
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244 | ///\todo Better memory allocation (instead of new). |
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245 | void create_maps() |
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246 | { |
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247 | if(!_pred) { |
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248 | local_pred = true; |
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249 | _pred = Traits::createPredMap(*G); |
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250 | } |
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251 | if(!_predNode) { |
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252 | local_predNode = true; |
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253 | _predNode = Traits::createPredNodeMap(*G); |
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254 | } |
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255 | if(!_dist) { |
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256 | local_dist = true; |
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257 | _dist = Traits::createDistMap(*G); |
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258 | } |
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259 | if(!_reached) { |
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260 | local_reached = true; |
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261 | _reached = Traits::createReachedMap(*G); |
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262 | } |
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263 | } |
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264 | |
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265 | public : |
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266 | |
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267 | ///\name Named template parameters |
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268 | |
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269 | ///@{ |
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270 | |
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271 | template <class T> |
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272 | struct DefPredMapTraits : public Traits { |
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273 | typedef T PredMap; |
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274 | static PredMap *createPredMap(const Graph &G) |
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275 | { |
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276 | throw UninitializedParameter(); |
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277 | } |
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278 | }; |
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279 | ///\ref named-templ-param "Named parameter" for setting PredMap type |
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280 | |
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281 | ///\ref named-templ-param "Named parameter" for setting PredMap type |
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282 | /// |
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283 | template <class T> |
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284 | class DefPredMap : public Dijkstra< Graph, |
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285 | LengthMap, |
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286 | DefPredMapTraits<T> > { }; |
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287 | |
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288 | template <class T> |
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289 | struct DefPredNodeMapTraits : public Traits { |
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290 | typedef T PredNodeMap; |
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291 | static PredNodeMap *createPredNodeMap(const Graph &G) |
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292 | { |
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293 | throw UninitializedParameter(); |
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294 | } |
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295 | }; |
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296 | ///\ref named-templ-param "Named parameter" for setting PredNodeMap type |
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297 | |
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298 | ///\ref named-templ-param "Named parameter" for setting PredNodeMap type |
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299 | /// |
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300 | template <class T> |
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301 | class DefPredNodeMap : public Dijkstra< Graph, |
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302 | LengthMap, |
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303 | DefPredNodeMapTraits<T> > { }; |
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304 | |
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305 | template <class T> |
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306 | struct DefDistMapTraits : public Traits { |
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307 | typedef T DistMap; |
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308 | static DistMap *createDistMap(const Graph &G) |
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309 | { |
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310 | throw UninitializedParameter(); |
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311 | } |
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312 | }; |
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313 | ///\ref named-templ-param "Named parameter" for setting DistMap type |
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314 | |
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315 | ///\ref named-templ-param "Named parameter" for setting DistMap type |
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316 | /// |
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317 | template <class T> |
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318 | class DefDistMap : public Dijkstra< Graph, |
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319 | LengthMap, |
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320 | DefDistMapTraits<T> > { }; |
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321 | |
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322 | template <class T> |
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323 | struct DefReachedMapTraits : public Traits { |
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324 | typedef T ReachedMap; |
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325 | static ReachedMap *createReachedMap(const Graph &G) |
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326 | { |
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327 | throw UninitializedParameter(); |
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328 | } |
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329 | }; |
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330 | ///\ref named-templ-param "Named parameter" for setting ReachedMap type |
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331 | |
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332 | ///\ref named-templ-param "Named parameter" for setting ReachedMap type |
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333 | /// |
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334 | template <class T> |
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335 | class DefReachedMap : public Dijkstra< Graph, |
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336 | LengthMap, |
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337 | DefReachedMapTraits<T> > { }; |
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338 | |
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339 | struct DefGraphReachedMapTraits : public Traits { |
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340 | typedef typename Graph::template NodeMap<bool> ReachedMap; |
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341 | static ReachedMap *createReachedMap(const Graph &G) |
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342 | { |
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343 | return new ReachedMap(G); |
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344 | } |
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345 | }; |
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346 | ///\brief \ref named-templ-param "Named parameter" |
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347 | ///for setting the ReachedMap type to be Graph::NodeMap<bool>. |
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348 | /// |
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349 | ///\ref named-templ-param "Named parameter" |
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350 | ///for setting the ReachedMap type to be Graph::NodeMap<bool>. |
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351 | ///If you don't set it explicitely, it will be automatically allocated. |
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352 | template <class T> |
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353 | class DefReachedMapToBeDefaultMap : |
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354 | public Dijkstra< Graph, |
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355 | LengthMap, |
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356 | DefGraphReachedMapTraits> { }; |
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357 | |
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358 | ///@} |
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359 | |
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360 | |
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361 | private: |
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362 | typename Graph::template NodeMap<int> _heap_map; |
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363 | Heap _heap; |
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364 | public: |
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365 | |
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366 | ///Constructor. |
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367 | |
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368 | ///\param _G the graph the algorithm will run on. |
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369 | ///\param _length the length map used by the algorithm. |
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370 | Dijkstra(const Graph& _G, const LengthMap& _length) : |
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371 | G(&_G), length(&_length), |
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372 | _pred(NULL), local_pred(false), |
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373 | _predNode(NULL), local_predNode(false), |
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374 | _dist(NULL), local_dist(false), |
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375 | _reached(NULL), local_reached(false), |
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376 | _heap_map(*G,-1),_heap(_heap_map) |
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377 | { } |
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378 | |
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379 | ///Destructor. |
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380 | ~Dijkstra() |
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381 | { |
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382 | if(local_pred) delete _pred; |
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383 | if(local_predNode) delete _predNode; |
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384 | if(local_dist) delete _dist; |
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385 | if(local_reached) delete _reached; |
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386 | } |
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387 | |
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388 | ///Sets the length map. |
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389 | |
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390 | ///Sets the length map. |
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391 | ///\return <tt> (*this) </tt> |
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392 | Dijkstra &lengthMap(const LengthMap &m) |
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393 | { |
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394 | length = &m; |
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395 | return *this; |
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396 | } |
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397 | |
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398 | ///Sets the map storing the predecessor edges. |
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399 | |
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400 | ///Sets the map storing the predecessor edges. |
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401 | ///If you don't use this function before calling \ref run(), |
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402 | ///it will allocate one. The destuctor deallocates this |
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403 | ///automatically allocated map, of course. |
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404 | ///\return <tt> (*this) </tt> |
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405 | Dijkstra &predMap(PredMap &m) |
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406 | { |
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407 | if(local_pred) { |
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408 | delete _pred; |
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409 | local_pred=false; |
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410 | } |
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411 | _pred = &m; |
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412 | return *this; |
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413 | } |
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414 | |
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415 | ///Sets the map storing the predecessor nodes. |
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416 | |
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417 | ///Sets the map storing the predecessor nodes. |
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418 | ///If you don't use this function before calling \ref run(), |
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419 | ///it will allocate one. The destuctor deallocates this |
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420 | ///automatically allocated map, of course. |
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421 | ///\return <tt> (*this) </tt> |
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422 | Dijkstra &predNodeMap(PredNodeMap &m) |
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423 | { |
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424 | if(local_predNode) { |
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425 | delete _predNode; |
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426 | local_predNode=false; |
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427 | } |
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428 | _predNode = &m; |
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429 | return *this; |
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430 | } |
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431 | |
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432 | ///Sets the map storing the distances calculated by the algorithm. |
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433 | |
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434 | ///Sets the map storing the distances calculated by the algorithm. |
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435 | ///If you don't use this function before calling \ref run(), |
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436 | ///it will allocate one. The destuctor deallocates this |
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437 | ///automatically allocated map, of course. |
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438 | ///\return <tt> (*this) </tt> |
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439 | Dijkstra &distMap(DistMap &m) |
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440 | { |
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441 | if(local_dist) { |
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442 | delete _dist; |
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443 | local_dist=false; |
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444 | } |
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445 | _dist = &m; |
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446 | return *this; |
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447 | } |
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448 | |
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449 | private: |
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450 | void finalizeNodeData(Node v,Value dst) |
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451 | { |
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452 | _reached->set(v,true); |
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453 | _dist->set(v, dst); |
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454 | if((*_pred)[v]!=INVALID) _predNode->set(v,G->source((*_pred)[v])); ///\todo What to do? |
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455 | } |
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456 | |
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457 | public: |
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458 | ///\name Excetution control |
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459 | ///The simplest way to execute the algorithm is to use |
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460 | ///one of the member functions called \c run(...). |
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461 | ///\n |
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462 | ///It you need more control on the execution, |
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463 | ///first you must call \ref init(), then you can add several source nodes |
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464 | ///with \ref addSource(). Finally \ref start() will perform the actual path |
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465 | ///computation. |
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466 | |
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467 | ///@{ |
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468 | |
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469 | ///Initializes the internal data structures. |
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470 | |
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471 | ///Initializes the internal data structures. |
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472 | /// |
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473 | ///\todo _heap_map's type could also be in the traits class. |
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474 | void init() |
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475 | { |
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476 | create_maps(); |
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477 | |
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478 | for ( NodeIt u(*G) ; u!=INVALID ; ++u ) { |
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479 | _pred->set(u,INVALID); |
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480 | _predNode->set(u,INVALID); |
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481 | ///\todo *_reached is not set to false. |
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482 | _heap_map.set(u,Heap::PRE_HEAP); |
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483 | } |
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484 | } |
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485 | |
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486 | ///Adds a new source node. |
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487 | |
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488 | ///Adds a new source node to the priority heap. |
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489 | /// |
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490 | ///The optional second parameter is the initial distance of the node. |
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491 | /// |
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492 | ///It checks if the node has already been added to the heap and |
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493 | ///It is pushed to the heap only if either it was not in the heap |
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494 | ///or the shortest path found till then is longer then \c dst. |
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495 | void addSource(Node s,Value dst=0) |
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496 | { |
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497 | source = s; |
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498 | if(_heap.state(s) != Heap::IN_HEAP) _heap.push(s,dst); |
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499 | else if(_heap[s]<dst) { |
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500 | _heap.push(s,dst); |
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501 | _pred->set(s,INVALID); |
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502 | } |
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503 | } |
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504 | |
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505 | ///Processes the next node in the priority heap |
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506 | |
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507 | ///Processes the next node in the priority heap. |
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508 | /// |
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509 | ///\warning The priority heap must not be empty! |
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510 | void processNextNode() |
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511 | { |
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512 | Node v=_heap.top(); |
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513 | Value oldvalue=_heap[v]; |
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514 | _heap.pop(); |
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515 | finalizeNodeData(v,oldvalue); |
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516 | |
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517 | for(OutEdgeIt e(*G,v); e!=INVALID; ++e) { |
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518 | Node w=G->target(e); |
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519 | switch(_heap.state(w)) { |
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520 | case Heap::PRE_HEAP: |
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521 | _heap.push(w,oldvalue+(*length)[e]); |
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522 | _pred->set(w,e); |
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523 | // _predNode->set(w,v); |
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524 | break; |
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525 | case Heap::IN_HEAP: |
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526 | if ( oldvalue+(*length)[e] < _heap[w] ) { |
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527 | _heap.decrease(w, oldvalue+(*length)[e]); |
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528 | _pred->set(w,e); |
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529 | // _predNode->set(w,v); |
---|
530 | } |
---|
531 | break; |
---|
532 | case Heap::POST_HEAP: |
---|
533 | break; |
---|
534 | } |
---|
535 | } |
---|
536 | } |
---|
537 | |
---|
538 | ///Returns \c false if there are nodes to be processed in the priority heap |
---|
539 | |
---|
540 | ///Returns \c false if there are nodes to be processed in the priority heap |
---|
541 | /// |
---|
542 | bool emptyHeap() { return _heap.empty(); } |
---|
543 | ///Returns the number of the nodes to be processed in the priority heap |
---|
544 | |
---|
545 | ///Returns the number of the nodes to be processed in the priority heap |
---|
546 | /// |
---|
547 | int heapSize() { return _heap.size(); } |
---|
548 | |
---|
549 | ///Executes the algorithm. |
---|
550 | |
---|
551 | ///Executes the algorithm. |
---|
552 | /// |
---|
553 | ///\pre init() must be called and at least one node should be added |
---|
554 | ///with addSource() before using this function. |
---|
555 | /// |
---|
556 | ///This method runs the %Dijkstra algorithm from the root node(s) |
---|
557 | ///in order to |
---|
558 | ///compute the |
---|
559 | ///shortest path to each node. The algorithm computes |
---|
560 | ///- The shortest path tree. |
---|
561 | ///- The distance of each node from the root(s). |
---|
562 | /// |
---|
563 | void start() |
---|
564 | { |
---|
565 | while ( !_heap.empty() ) processNextNode(); |
---|
566 | } |
---|
567 | |
---|
568 | ///Executes the algorithm until \c dest is reached. |
---|
569 | |
---|
570 | ///Executes the algorithm until \c dest is reached. |
---|
571 | /// |
---|
572 | ///\pre init() must be called and at least one node should be added |
---|
573 | ///with addSource() before using this function. |
---|
574 | /// |
---|
575 | ///This method runs the %Dijkstra algorithm from the root node(s) |
---|
576 | ///in order to |
---|
577 | ///compute the |
---|
578 | ///shortest path to \c dest. The algorithm computes |
---|
579 | ///- The shortest path to \c dest. |
---|
580 | ///- The distance of \c dest from the root(s). |
---|
581 | /// |
---|
582 | void start(Node dest) |
---|
583 | { |
---|
584 | while ( !_heap.empty() && _heap.top()!=dest ) processNextNode(); |
---|
585 | if ( _heap.top()==dest ) finalizeNodeData(_heap.top()); |
---|
586 | } |
---|
587 | |
---|
588 | ///Executes the algorithm until a condition is met. |
---|
589 | |
---|
590 | ///Executes the algorithm until a condition is met. |
---|
591 | /// |
---|
592 | ///\pre init() must be called and at least one node should be added |
---|
593 | ///with addSource() before using this function. |
---|
594 | /// |
---|
595 | ///\param nm must be a bool (or convertible) node map. The algorithm |
---|
596 | ///will stop when it reaches a node \c v with <tt>nm[v]==true</tt>. |
---|
597 | template<class NM> |
---|
598 | void start(const NM &nm) |
---|
599 | { |
---|
600 | while ( !_heap.empty() && !nm[_heap.top()] ) processNextNode(); |
---|
601 | if ( !_heap.empty() ) finalizeNodeData(_heap.top()); |
---|
602 | } |
---|
603 | |
---|
604 | ///Runs %Dijkstra algorithm from node \c s. |
---|
605 | |
---|
606 | ///This method runs the %Dijkstra algorithm from a root node \c s |
---|
607 | ///in order to |
---|
608 | ///compute the |
---|
609 | ///shortest path to each node. The algorithm computes |
---|
610 | ///- The shortest path tree. |
---|
611 | ///- The distance of each node from the root. |
---|
612 | /// |
---|
613 | ///\note d.run(s) is just a shortcut of the following code. |
---|
614 | ///\code |
---|
615 | /// d.init(); |
---|
616 | /// d.addSource(s); |
---|
617 | /// d.start(); |
---|
618 | ///\endcode |
---|
619 | void run(Node s) { |
---|
620 | init(); |
---|
621 | addSource(s); |
---|
622 | start(); |
---|
623 | } |
---|
624 | |
---|
625 | ///Finds the shortest path between \c s and \c t. |
---|
626 | |
---|
627 | ///Finds the shortest path between \c s and \c t. |
---|
628 | /// |
---|
629 | ///\return The length of the shortest s---t path if there exists one, |
---|
630 | ///0 otherwise. |
---|
631 | ///\note Apart from the return value, d.run(s) is |
---|
632 | ///just a shortcut of the following code. |
---|
633 | ///\code |
---|
634 | /// d.init(); |
---|
635 | /// d.addSource(s); |
---|
636 | /// d.start(t); |
---|
637 | ///\endcode |
---|
638 | Value run(Node s,Node t) { |
---|
639 | init(); |
---|
640 | addSource(s); |
---|
641 | start(t); |
---|
642 | return (*_pred)[t]==INVALID?0:(*_dist)[t]; |
---|
643 | } |
---|
644 | |
---|
645 | ///@} |
---|
646 | |
---|
647 | ///\name Query Functions |
---|
648 | ///The result of the %Dijkstra algorithm can be obtained using these |
---|
649 | ///functions.\n |
---|
650 | ///Before the use of these functions, |
---|
651 | ///either run() or start() must be called. |
---|
652 | |
---|
653 | ///@{ |
---|
654 | |
---|
655 | ///The distance of a node from the root. |
---|
656 | |
---|
657 | ///Returns the distance of a node from the root. |
---|
658 | ///\pre \ref run() must be called before using this function. |
---|
659 | ///\warning If node \c v in unreachable from the root the return value |
---|
660 | ///of this funcion is undefined. |
---|
661 | Value dist(Node v) const { return (*_dist)[v]; } |
---|
662 | |
---|
663 | ///Returns the 'previous edge' of the shortest path tree. |
---|
664 | |
---|
665 | ///For a node \c v it returns the 'previous edge' of the shortest path tree, |
---|
666 | ///i.e. it returns the last edge of a shortest path from the root to \c |
---|
667 | ///v. It is \ref INVALID |
---|
668 | ///if \c v is unreachable from the root or if \c v=s. The |
---|
669 | ///shortest path tree used here is equal to the shortest path tree used in |
---|
670 | ///\ref predNode(Node v). \pre \ref run() must be called before using |
---|
671 | ///this function. |
---|
672 | ///\todo predEdge could be a better name. |
---|
673 | Edge pred(Node v) const { return (*_pred)[v]; } |
---|
674 | |
---|
675 | ///Returns the 'previous node' of the shortest path tree. |
---|
676 | |
---|
677 | ///For a node \c v it returns the 'previous node' of the shortest path tree, |
---|
678 | ///i.e. it returns the last but one node from a shortest path from the |
---|
679 | ///root to \c /v. It is INVALID if \c v is unreachable from the root or if |
---|
680 | ///\c v=s. The shortest path tree used here is equal to the shortest path |
---|
681 | ///tree used in \ref pred(Node v). \pre \ref run() must be called before |
---|
682 | ///using this function. |
---|
683 | Node predNode(Node v) const { return (*_pred)[v]==INVALID ? INVALID: |
---|
684 | G->source((*_pred)[v]); } |
---|
685 | |
---|
686 | ///Returns a reference to the NodeMap of distances. |
---|
687 | |
---|
688 | ///Returns a reference to the NodeMap of distances. \pre \ref run() must |
---|
689 | ///be called before using this function. |
---|
690 | const DistMap &distMap() const { return *_dist;} |
---|
691 | |
---|
692 | ///Returns a reference to the shortest path tree map. |
---|
693 | |
---|
694 | ///Returns a reference to the NodeMap of the edges of the |
---|
695 | ///shortest path tree. |
---|
696 | ///\pre \ref run() must be called before using this function. |
---|
697 | const PredMap &predMap() const { return *_pred;} |
---|
698 | |
---|
699 | ///Returns a reference to the map of nodes of shortest paths. |
---|
700 | |
---|
701 | ///Returns a reference to the NodeMap of the last but one nodes of the |
---|
702 | ///shortest path tree. |
---|
703 | ///\pre \ref run() must be called before using this function. |
---|
704 | const PredNodeMap &predNodeMap() const { return *_predNode;} |
---|
705 | |
---|
706 | ///Checks if a node is reachable from the root. |
---|
707 | |
---|
708 | ///Returns \c true if \c v is reachable from the root. |
---|
709 | ///\warning If the algorithm is started from multiple nodes, |
---|
710 | ///this function may give false result for the source nodes. |
---|
711 | ///\pre \ref run() must be called before using this function. |
---|
712 | /// |
---|
713 | bool reached(Node v) { return v==source || (*_pred)[v]!=INVALID; } |
---|
714 | |
---|
715 | ///@} |
---|
716 | }; |
---|
717 | |
---|
718 | /// Default traits used by \ref DijkstraWizard |
---|
719 | |
---|
720 | /// To make it easier to use Dijkstra algorithm |
---|
721 | ///we have created a wizard class. |
---|
722 | /// This \ref DijkstraWizard class needs default traits, |
---|
723 | ///as well as the \ref Dijkstra class. |
---|
724 | /// The \ref DijkstraWizardBase is a class to be the default traits of the |
---|
725 | /// \ref DijkstraWizard class. |
---|
726 | template<class GR,class LM> |
---|
727 | class DijkstraWizardBase : public DijkstraDefaultTraits<GR,LM> |
---|
728 | { |
---|
729 | |
---|
730 | typedef DijkstraDefaultTraits<GR,LM> Base; |
---|
731 | protected: |
---|
732 | /// Pointer to the underlying graph. |
---|
733 | void *_g; |
---|
734 | /// Pointer to the length map |
---|
735 | void *_length; |
---|
736 | ///Pointer to the map of predecessors edges. |
---|
737 | void *_pred; |
---|
738 | ///Pointer to the map of predecessors nodes. |
---|
739 | void *_predNode; |
---|
740 | ///Pointer to the map of distances. |
---|
741 | void *_dist; |
---|
742 | ///Pointer to the source node. |
---|
743 | void *_source; |
---|
744 | |
---|
745 | /// Type of the nodes in the graph. |
---|
746 | typedef typename Base::Graph::Node Node; |
---|
747 | |
---|
748 | public: |
---|
749 | /// Constructor. |
---|
750 | |
---|
751 | /// This constructor does not require parameters, therefore it initiates |
---|
752 | /// all of the attributes to default values (0, INVALID). |
---|
753 | DijkstraWizardBase() : _g(0), _length(0), _pred(0), _predNode(0), |
---|
754 | _dist(0), _source(0) {} |
---|
755 | |
---|
756 | /// Constructor. |
---|
757 | |
---|
758 | /// This constructor requires some parameters, |
---|
759 | /// listed in the parameters list. |
---|
760 | /// Others are initiated to 0. |
---|
761 | /// \param g is the initial value of \ref _g |
---|
762 | /// \param l is the initial value of \ref _length |
---|
763 | /// \param s is the initial value of \ref _source |
---|
764 | DijkstraWizardBase(const GR &g,const LM &l, Node s=INVALID) : |
---|
765 | _g((void *)&g), _length((void *)&l), _pred(0), _predNode(0), |
---|
766 | _dist(0), _source((s==INVALID)?0:(void *)&s) {} |
---|
767 | |
---|
768 | }; |
---|
769 | |
---|
770 | /// A class to make easier the usage of Dijkstra algorithm |
---|
771 | |
---|
772 | /// \ingroup flowalgs |
---|
773 | /// This class is created to make it easier to use Dijkstra algorithm. |
---|
774 | /// It uses the functions and features of the plain \ref Dijkstra, |
---|
775 | /// but it is much simpler to use it. |
---|
776 | /// |
---|
777 | /// Simplicity means that the way to change the types defined |
---|
778 | /// in the traits class is based on functions that returns the new class |
---|
779 | /// and not on templatable built-in classes. |
---|
780 | /// When using the plain \ref Dijkstra |
---|
781 | /// the new class with the modified type comes from |
---|
782 | /// the original class by using the :: |
---|
783 | /// operator. In the case of \ref DijkstraWizard only |
---|
784 | /// a function have to be called and it will |
---|
785 | /// return the needed class. |
---|
786 | /// |
---|
787 | /// It does not have own \ref run method. When its \ref run method is called |
---|
788 | /// it initiates a plain \ref Dijkstra class, and calls the \ref Dijkstra::run |
---|
789 | /// method of it. |
---|
790 | template<class TR> |
---|
791 | class DijkstraWizard : public TR |
---|
792 | { |
---|
793 | typedef TR Base; |
---|
794 | |
---|
795 | ///The type of the underlying graph. |
---|
796 | typedef typename TR::Graph Graph; |
---|
797 | //\e |
---|
798 | typedef typename Graph::Node Node; |
---|
799 | //\e |
---|
800 | typedef typename Graph::NodeIt NodeIt; |
---|
801 | //\e |
---|
802 | typedef typename Graph::Edge Edge; |
---|
803 | //\e |
---|
804 | typedef typename Graph::OutEdgeIt OutEdgeIt; |
---|
805 | |
---|
806 | ///The type of the map that stores the edge lengths. |
---|
807 | typedef typename TR::LengthMap LengthMap; |
---|
808 | ///The type of the length of the edges. |
---|
809 | typedef typename LengthMap::Value Value; |
---|
810 | ///\brief The type of the map that stores the last |
---|
811 | ///edges of the shortest paths. |
---|
812 | typedef typename TR::PredMap PredMap; |
---|
813 | ///\brief The type of the map that stores the last but one |
---|
814 | ///nodes of the shortest paths. |
---|
815 | typedef typename TR::PredNodeMap PredNodeMap; |
---|
816 | ///The type of the map that stores the dists of the nodes. |
---|
817 | typedef typename TR::DistMap DistMap; |
---|
818 | |
---|
819 | ///The heap type used by the dijkstra algorithm. |
---|
820 | typedef typename TR::Heap Heap; |
---|
821 | public: |
---|
822 | /// Constructor. |
---|
823 | DijkstraWizard() : TR() {} |
---|
824 | |
---|
825 | /// Constructor that requires parameters. |
---|
826 | |
---|
827 | /// Constructor that requires parameters. |
---|
828 | /// These parameters will be the default values for the traits class. |
---|
829 | DijkstraWizard(const Graph &g,const LengthMap &l, Node s=INVALID) : |
---|
830 | TR(g,l,s) {} |
---|
831 | |
---|
832 | ///Copy constructor |
---|
833 | DijkstraWizard(const TR &b) : TR(b) {} |
---|
834 | |
---|
835 | ~DijkstraWizard() {} |
---|
836 | |
---|
837 | ///Runs Dijkstra algorithm from a given node. |
---|
838 | |
---|
839 | ///Runs Dijkstra algorithm from a given node. |
---|
840 | ///The node can be given by the \ref source function. |
---|
841 | void run() |
---|
842 | { |
---|
843 | if(Base::_source==0) throw UninitializedParameter(); |
---|
844 | Dijkstra<Graph,LengthMap,TR> |
---|
845 | Dij(*(Graph*)Base::_g,*(LengthMap*)Base::_length); |
---|
846 | if(Base::_pred) Dij.predMap(*(PredMap*)Base::_pred); |
---|
847 | if(Base::_predNode) Dij.predNodeMap(*(PredNodeMap*)Base::_predNode); |
---|
848 | if(Base::_dist) Dij.distMap(*(DistMap*)Base::_dist); |
---|
849 | Dij.run(*(Node*)Base::_source); |
---|
850 | } |
---|
851 | |
---|
852 | ///Runs Dijkstra algorithm from the given node. |
---|
853 | |
---|
854 | ///Runs Dijkstra algorithm from the given node. |
---|
855 | ///\param s is the given source. |
---|
856 | void run(Node s) |
---|
857 | { |
---|
858 | Base::_source=(void *)&s; |
---|
859 | run(); |
---|
860 | } |
---|
861 | |
---|
862 | template<class T> |
---|
863 | struct DefPredMapBase : public Base { |
---|
864 | typedef T PredMap; |
---|
865 | static PredMap *createPredMap(const Graph &G) { return 0; }; |
---|
866 | DefPredMapBase(const Base &b) : Base(b) {} |
---|
867 | }; |
---|
868 | |
---|
869 | ///\brief \ref named-templ-param "Named parameter" |
---|
870 | ///function for setting PredMap type |
---|
871 | /// |
---|
872 | /// \ref named-templ-param "Named parameter" |
---|
873 | ///function for setting PredMap type |
---|
874 | /// |
---|
875 | template<class T> |
---|
876 | DijkstraWizard<DefPredMapBase<T> > predMap(const T &t) |
---|
877 | { |
---|
878 | Base::_pred=(void *)&t; |
---|
879 | return DijkstraWizard<DefPredMapBase<T> >(*this); |
---|
880 | } |
---|
881 | |
---|
882 | |
---|
883 | template<class T> |
---|
884 | struct DefPredNodeMapBase : public Base { |
---|
885 | typedef T PredNodeMap; |
---|
886 | static PredNodeMap *createPredNodeMap(const Graph &G) { return 0; }; |
---|
887 | DefPredNodeMapBase(const Base &b) : Base(b) {} |
---|
888 | }; |
---|
889 | |
---|
890 | ///\brief \ref named-templ-param "Named parameter" |
---|
891 | ///function for setting PredNodeMap type |
---|
892 | /// |
---|
893 | /// \ref named-templ-param "Named parameter" |
---|
894 | ///function for setting PredNodeMap type |
---|
895 | /// |
---|
896 | template<class T> |
---|
897 | DijkstraWizard<DefPredNodeMapBase<T> > predNodeMap(const T &t) |
---|
898 | { |
---|
899 | Base::_predNode=(void *)&t; |
---|
900 | return DijkstraWizard<DefPredNodeMapBase<T> >(*this); |
---|
901 | } |
---|
902 | |
---|
903 | template<class T> |
---|
904 | struct DefDistMapBase : public Base { |
---|
905 | typedef T DistMap; |
---|
906 | static DistMap *createDistMap(const Graph &G) { return 0; }; |
---|
907 | DefDistMapBase(const Base &b) : Base(b) {} |
---|
908 | }; |
---|
909 | |
---|
910 | ///\brief \ref named-templ-param "Named parameter" |
---|
911 | ///function for setting DistMap type |
---|
912 | /// |
---|
913 | /// \ref named-templ-param "Named parameter" |
---|
914 | ///function for setting DistMap type |
---|
915 | /// |
---|
916 | template<class T> |
---|
917 | DijkstraWizard<DefDistMapBase<T> > distMap(const T &t) |
---|
918 | { |
---|
919 | Base::_dist=(void *)&t; |
---|
920 | return DijkstraWizard<DefDistMapBase<T> >(*this); |
---|
921 | } |
---|
922 | |
---|
923 | /// Sets the source node, from which the Dijkstra algorithm runs. |
---|
924 | |
---|
925 | /// Sets the source node, from which the Dijkstra algorithm runs. |
---|
926 | /// \param s is the source node. |
---|
927 | DijkstraWizard<TR> &source(Node s) |
---|
928 | { |
---|
929 | Base::_source=(void *)&s; |
---|
930 | return *this; |
---|
931 | } |
---|
932 | |
---|
933 | }; |
---|
934 | |
---|
935 | ///\e |
---|
936 | |
---|
937 | /// \ingroup flowalgs |
---|
938 | ///\todo Please document... |
---|
939 | /// |
---|
940 | template<class GR, class LM> |
---|
941 | DijkstraWizard<DijkstraWizardBase<GR,LM> > |
---|
942 | dijkstra(const GR &g,const LM &l,typename GR::Node s=INVALID) |
---|
943 | { |
---|
944 | return DijkstraWizard<DijkstraWizardBase<GR,LM> >(g,l,s); |
---|
945 | } |
---|
946 | |
---|
947 | /// @} |
---|
948 | |
---|
949 | } //END OF NAMESPACE LEMON |
---|
950 | |
---|
951 | #endif |
---|
952 | |
---|