1 | /* -*- C++ -*- |
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2 | * |
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3 | * This file is a part of LEMON, a generic C++ optimization library |
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4 | * |
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5 | * Copyright (C) 2003-2006 |
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6 | * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport |
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7 | * (Egervary Research Group on Combinatorial Optimization, EGRES). |
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8 | * |
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9 | * Permission to use, modify and distribute this software is granted |
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10 | * provided that this copyright notice appears in all copies. For |
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11 | * precise terms see the accompanying LICENSE file. |
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12 | * |
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13 | * This software is provided "AS IS" with no warranty of any kind, |
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14 | * express or implied, and with no claim as to its suitability for any |
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15 | * purpose. |
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16 | * |
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17 | */ |
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18 | |
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19 | #ifndef LEMON_DAG_SHORTEST_PATH_H |
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20 | #define LEMON_DAG_SHORTEST_PATH_H |
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21 | |
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22 | ///\ingroup flowalgs |
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23 | /// \file |
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24 | /// \brief DagShortestPath algorithm. |
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25 | /// |
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26 | |
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27 | #include <lemon/list_graph.h> |
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28 | #include <lemon/bits/invalid.h> |
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29 | #include <lemon/error.h> |
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30 | #include <lemon/maps.h> |
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31 | #include <lemon/topology.h> |
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32 | |
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33 | #include <limits> |
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34 | |
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35 | namespace lemon { |
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36 | |
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37 | /// \brief Default OperationTraits for the DagShortestPath algorithm class. |
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38 | /// |
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39 | /// It defines all computational operations and constants which are |
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40 | /// used in the dag shortest path algorithm. The default implementation |
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41 | /// is based on the numeric_limits class. If the numeric type does not |
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42 | /// have infinity value then the maximum value is used as extremal |
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43 | /// infinity value. |
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44 | template < |
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45 | typename Value, |
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46 | bool has_infinity = std::numeric_limits<Value>::has_infinity> |
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47 | struct DagShortestPathDefaultOperationTraits { |
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48 | /// \brief Gives back the zero value of the type. |
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49 | static Value zero() { |
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50 | return static_cast<Value>(0); |
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51 | } |
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52 | /// \brief Gives back the positive infinity value of the type. |
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53 | static Value infinity() { |
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54 | return std::numeric_limits<Value>::infinity(); |
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55 | } |
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56 | /// \brief Gives back the sum of the given two elements. |
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57 | static Value plus(const Value& left, const Value& right) { |
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58 | return left + right; |
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59 | } |
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60 | /// \brief Gives back true only if the first value less than the second. |
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61 | static bool less(const Value& left, const Value& right) { |
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62 | return left < right; |
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63 | } |
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64 | }; |
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65 | |
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66 | template <typename Value> |
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67 | struct DagShortestPathDefaultOperationTraits<Value, false> { |
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68 | static Value zero() { |
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69 | return static_cast<Value>(0); |
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70 | } |
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71 | static Value infinity() { |
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72 | return std::numeric_limits<Value>::max(); |
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73 | } |
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74 | static Value plus(const Value& left, const Value& right) { |
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75 | if (left == infinity() || right == infinity()) return infinity(); |
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76 | return left + right; |
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77 | } |
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78 | static bool less(const Value& left, const Value& right) { |
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79 | return left < right; |
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80 | } |
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81 | }; |
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82 | |
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83 | /// \brief Default traits class of DagShortestPath class. |
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84 | /// |
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85 | /// Default traits class of DagShortestPath class. |
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86 | /// \param _Graph Graph type. |
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87 | /// \param _LegthMap Type of length map. |
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88 | template<class _Graph, class _LengthMap> |
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89 | struct DagShortestPathDefaultTraits { |
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90 | /// The graph type the algorithm runs on. |
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91 | typedef _Graph Graph; |
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92 | |
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93 | /// \brief The type of the map that stores the edge lengths. |
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94 | /// |
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95 | /// The type of the map that stores the edge lengths. |
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96 | /// It must meet the \ref concept::ReadMap "ReadMap" concept. |
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97 | typedef _LengthMap LengthMap; |
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98 | |
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99 | // The type of the length of the edges. |
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100 | typedef typename _LengthMap::Value Value; |
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101 | |
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102 | /// \brief Operation traits for dag shortest path algorithm. |
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103 | /// |
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104 | /// It defines the infinity type on the given Value type |
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105 | /// and the used operation. |
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106 | /// \see DagShortestPathDefaultOperationTraits |
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107 | typedef DagShortestPathDefaultOperationTraits<Value> OperationTraits; |
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108 | |
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109 | /// \brief The type of the map that stores the last edges of the |
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110 | /// shortest paths. |
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111 | /// |
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112 | /// The type of the map that stores the last |
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113 | /// edges of the shortest paths. |
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114 | /// It must meet the \ref concept::WriteMap "WriteMap" concept. |
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115 | /// |
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116 | typedef typename Graph::template NodeMap<typename _Graph::Edge> PredMap; |
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117 | |
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118 | /// \brief Instantiates a PredMap. |
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119 | /// |
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120 | /// This function instantiates a \ref PredMap. |
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121 | /// \param graph is the graph, to which we would |
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122 | /// like to define the PredMap. |
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123 | /// \todo The graph alone may be insufficient for the initialization |
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124 | static PredMap *createPredMap(const _Graph& graph) { |
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125 | return new PredMap(graph); |
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126 | } |
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127 | |
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128 | /// \brief The type of the map that stores the dists of the nodes. |
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129 | /// |
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130 | /// The type of the map that stores the dists of the nodes. |
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131 | /// It must meet the \ref concept::WriteMap "WriteMap" concept. |
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132 | /// |
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133 | typedef typename Graph::template NodeMap<typename _LengthMap::Value> |
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134 | DistMap; |
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135 | |
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136 | /// \brief Instantiates a DistMap. |
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137 | /// |
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138 | /// This function instantiates a \ref DistMap. |
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139 | /// \param graph is the graph, to which we would like to define the |
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140 | /// \ref DistMap |
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141 | static DistMap *createDistMap(const _Graph& graph) { |
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142 | return new DistMap(graph); |
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143 | } |
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144 | |
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145 | }; |
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146 | |
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147 | /// \brief Inverse OperationTraits for the DagShortestPath algorithm class. |
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148 | /// |
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149 | /// It defines all computational operations and constants which are |
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150 | /// used in the dag shortest path algorithm. It is the inverse of |
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151 | /// \ref DagShortestPathDefaultOperationTraits, so it can be used to |
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152 | /// calculate the longest path. The default implementation |
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153 | /// is based on the numeric_limits class. If the numeric type does not |
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154 | /// have infinity value then the minimum value is used as extremal |
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155 | /// infinity value. |
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156 | template < |
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157 | typename Value, |
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158 | bool has_infinity = std::numeric_limits<Value>::has_infinity> |
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159 | struct DagLongestPathOperationTraits { |
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160 | /// \brief Gives back the zero value of the type. |
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161 | static Value zero() { |
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162 | return static_cast<Value>(0); |
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163 | } |
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164 | /// \brief Gives back the negative infinity value of the type. |
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165 | static Value infinity() { |
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166 | return -(std::numeric_limits<Value>::infinity()); |
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167 | } |
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168 | /// \brief Gives back the sum of the given two elements. |
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169 | static Value plus(const Value& left, const Value& right) { |
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170 | return left + right; |
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171 | } |
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172 | /// \brief Gives back true only if the first value less than the second. |
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173 | static bool less(const Value& left, const Value& right) { |
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174 | return left > right; |
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175 | } |
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176 | }; |
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177 | |
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178 | template <typename Value> |
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179 | struct DagLongestPathOperationTraits<Value, false> { |
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180 | static Value zero() { |
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181 | return static_cast<Value>(0); |
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182 | } |
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183 | static Value infinity() { |
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184 | return std::numeric_limits<Value>::min(); |
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185 | } |
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186 | static Value plus(const Value& left, const Value& right) { |
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187 | if (left == infinity() || right == infinity()) return infinity(); |
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188 | return left + right; |
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189 | } |
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190 | static bool less(const Value& left, const Value& right) { |
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191 | return left > right; |
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192 | } |
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193 | }; |
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194 | |
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195 | /// \brief Inverse traits class of DagShortestPath class. |
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196 | /// |
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197 | /// Inverse traits class of DagShortestPath class. |
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198 | /// \param _Graph Graph type. |
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199 | /// \param _LegthMap Type of length map. |
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200 | template<class _Graph, class _LengthMap> |
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201 | struct DagLongestPathTraits { |
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202 | /// The graph type the algorithm runs on. |
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203 | typedef _Graph Graph; |
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204 | |
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205 | /// \brief The type of the map that stores the edge lengths. |
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206 | /// |
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207 | /// The type of the map that stores the edge lengths. |
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208 | /// It must meet the \ref concept::ReadMap "ReadMap" concept. |
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209 | typedef _LengthMap LengthMap; |
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210 | |
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211 | // The type of the length of the edges. |
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212 | typedef typename _LengthMap::Value Value; |
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213 | |
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214 | /// \brief Inverse operation traits for dag shortest path algorithm. |
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215 | /// |
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216 | /// It defines the infinity type on the given Value type |
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217 | /// and the used operation. |
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218 | /// \see DagLongestPathOperationTraits |
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219 | typedef DagLongestPathOperationTraits<Value> OperationTraits; |
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220 | |
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221 | /// \brief The type of the map that stores the last edges of the |
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222 | /// longest paths. |
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223 | /// |
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224 | /// The type of the map that stores the last |
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225 | /// edges of the longest paths. |
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226 | /// It must meet the \ref concept::WriteMap "WriteMap" concept. |
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227 | /// |
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228 | typedef typename Graph::template NodeMap<typename _Graph::Edge> PredMap; |
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229 | |
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230 | /// \brief Instantiates a PredMap. |
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231 | /// |
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232 | /// This function instantiates a \ref PredMap. |
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233 | /// \param graph is the graph, |
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234 | /// to which we would like to define the PredMap. |
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235 | /// \todo The graph alone may be insufficient for the initialization |
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236 | static PredMap *createPredMap(const _Graph& graph) { |
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237 | return new PredMap(graph); |
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238 | } |
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239 | |
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240 | /// \brief The type of the map that stores the dists of the nodes. |
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241 | /// |
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242 | /// The type of the map that stores the dists of the nodes. |
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243 | /// It must meet the \ref concept::WriteMap "WriteMap" concept. |
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244 | /// |
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245 | typedef typename Graph::template NodeMap<typename _LengthMap::Value> |
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246 | DistMap; |
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247 | |
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248 | /// \brief Instantiates a DistMap. |
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249 | /// |
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250 | /// This function instantiates a \ref DistMap. |
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251 | /// \param graph is the graph, to which we would like to define the |
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252 | /// \ref DistMap |
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253 | static DistMap *createDistMap(const _Graph& graph) { |
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254 | return new DistMap(graph); |
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255 | } |
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256 | |
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257 | }; |
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258 | |
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259 | |
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260 | /// \brief %DagShortestPath algorithm class. |
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261 | /// |
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262 | /// \ingroup flowalgs |
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263 | /// This class provides an efficient implementation of a Dag sortest path |
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264 | /// searching algorithm. The edge lengths are passed to the algorithm |
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265 | /// using a \ref concept::ReadMap "ReadMap", so it is easy to change it |
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266 | /// to any kind of length. |
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267 | /// |
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268 | /// The complexity of the algorithm is O(n + e). |
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269 | /// |
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270 | /// The type of the length is determined by the |
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271 | /// \ref concept::ReadMap::Value "Value" of the length map. |
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272 | /// |
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273 | /// \param _Graph The graph type the algorithm runs on. The default value |
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274 | /// is \ref ListGraph. The value of _Graph is not used directly by |
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275 | /// DagShortestPath, it is only passed to \ref DagShortestPathDefaultTraits. |
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276 | /// \param _LengthMap This read-only EdgeMap determines the lengths of the |
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277 | /// edges. The default map type is \ref concept::StaticGraph::EdgeMap |
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278 | /// "Graph::EdgeMap<int>". The value of _LengthMap is not used directly |
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279 | /// by DagShortestPath, it is only passed to \ref DagShortestPathDefaultTraits. |
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280 | /// \param _Traits Traits class to set various data types used by the |
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281 | /// algorithm. The default traits class is \ref DagShortestPathDefaultTraits |
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282 | /// "DagShortestPathDefaultTraits<_Graph,_LengthMap>". See \ref |
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283 | /// DagShortestPathDefaultTraits for the documentation of a DagShortestPath traits |
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284 | /// class. |
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285 | /// |
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286 | /// \author Balazs Attila Mihaly (based on Balazs Dezso's work) |
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287 | |
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288 | #ifdef DOXYGEN |
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289 | template <typename _Graph, typename _LengthMap, typename _Traits> |
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290 | #else |
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291 | template <typename _Graph=ListGraph, |
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292 | typename _LengthMap=typename _Graph::template EdgeMap<int>, |
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293 | typename _Traits=DagShortestPathDefaultTraits<_Graph,_LengthMap> > |
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294 | #endif |
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295 | class DagShortestPath { |
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296 | public: |
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297 | |
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298 | /// \brief \ref Exception for uninitialized parameters. |
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299 | /// |
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300 | /// This error represents problems in the initialization |
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301 | /// of the parameters of the algorithms. |
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302 | |
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303 | class UninitializedParameter : public lemon::UninitializedParameter { |
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304 | public: |
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305 | virtual const char* exceptionName() const { |
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306 | return "lemon::DagShortestPath::UninitializedParameter"; |
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307 | } |
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308 | }; |
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309 | |
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310 | typedef _Traits Traits; |
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311 | ///The type of the underlying graph. |
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312 | typedef typename _Traits::Graph Graph; |
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313 | |
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314 | typedef typename Graph::Node Node; |
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315 | typedef typename Graph::NodeIt NodeIt; |
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316 | typedef typename Graph::Edge Edge; |
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317 | typedef typename Graph::EdgeIt EdgeIt; |
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318 | typedef typename Graph::OutEdgeIt OutEdgeIt; |
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319 | |
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320 | /// \brief The type of the length of the edges. |
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321 | typedef typename _Traits::LengthMap::Value Value; |
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322 | /// \brief The type of the map that stores the edge lengths. |
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323 | typedef typename _Traits::LengthMap LengthMap; |
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324 | /// \brief The type of the map that stores the last |
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325 | /// edges of the shortest paths. |
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326 | typedef typename _Traits::PredMap PredMap; |
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327 | /// \brief The type of the map that stores the dists of the nodes. |
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328 | typedef typename _Traits::DistMap DistMap; |
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329 | /// \brief The operation traits. |
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330 | typedef typename _Traits::OperationTraits OperationTraits; |
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331 | /// \brief The Node weight map. |
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332 | typedef typename Graph::NodeMap<Value> WeightMap; |
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333 | private: |
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334 | /// Pointer to the underlying graph |
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335 | const Graph *graph; |
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336 | /// Pointer to the length map |
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337 | const LengthMap *length; |
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338 | ///Pointer to the map of predecessors edges |
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339 | PredMap *_pred; |
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340 | ///Indicates if \ref _pred is locally allocated (\c true) or not |
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341 | bool local_pred; |
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342 | ///Pointer to the map of distances |
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343 | DistMap *_dist; |
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344 | ///Indicates if \ref _dist is locally allocated (\c true) or not |
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345 | bool local_dist; |
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346 | ///Process step counter |
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347 | unsigned int _process_step; |
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348 | |
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349 | std::vector<Node> _node_order; |
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350 | |
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351 | /// Creates the maps if necessary. |
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352 | void create_maps() { |
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353 | if(!_pred) { |
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354 | local_pred = true; |
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355 | _pred = Traits::createPredMap(*graph); |
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356 | } |
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357 | if(!_dist) { |
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358 | local_dist = true; |
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359 | _dist = Traits::createDistMap(*graph); |
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360 | } |
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361 | } |
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362 | |
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363 | public : |
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364 | |
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365 | typedef DagShortestPath Create; |
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366 | |
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367 | /// \name Named template parameters |
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368 | |
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369 | ///@{ |
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370 | |
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371 | template <class T> |
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372 | struct DefPredMapTraits : public Traits { |
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373 | typedef T PredMap; |
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374 | static PredMap *createPredMap(const Graph&) { |
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375 | throw UninitializedParameter(); |
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376 | } |
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377 | }; |
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378 | |
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379 | /// \brief \ref named-templ-param "Named parameter" for setting PredMap |
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380 | /// type |
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381 | /// \ref named-templ-param "Named parameter" for setting PredMap type |
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382 | /// |
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383 | template <class T> |
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384 | struct DefPredMap { |
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385 | typedef DagShortestPath< Graph, LengthMap, DefPredMapTraits<T> > Create; |
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386 | }; |
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387 | |
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388 | template <class T> |
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389 | struct DefDistMapTraits : public Traits { |
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390 | typedef T DistMap; |
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391 | static DistMap *createDistMap(const Graph& graph) { |
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392 | throw UninitializedParameter(); |
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393 | } |
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394 | }; |
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395 | |
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396 | /// \brief \ref named-templ-param "Named parameter" for setting DistMap |
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397 | /// type |
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398 | /// |
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399 | /// \ref named-templ-param "Named parameter" for setting DistMap type |
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400 | /// |
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401 | template <class T> |
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402 | struct DefDistMap |
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403 | : public DagShortestPath< Graph, LengthMap, DefDistMapTraits<T> > { |
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404 | typedef DagShortestPath< Graph, LengthMap, DefDistMapTraits<T> > Create; |
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405 | }; |
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406 | |
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407 | template <class T> |
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408 | struct DefOperationTraitsTraits : public Traits { |
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409 | typedef T OperationTraits; |
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410 | }; |
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411 | |
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412 | /// \brief \ref named-templ-param "Named parameter" for setting |
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413 | /// OperationTraits type |
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414 | /// |
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415 | /// \ref named-templ-param "Named parameter" for setting OperationTraits |
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416 | /// type |
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417 | template <class T> |
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418 | struct DefOperationTraits |
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419 | : public DagShortestPath< Graph, LengthMap, DefOperationTraitsTraits<T> > { |
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420 | typedef DagShortestPath< Graph, LengthMap, DefOperationTraitsTraits<T> > |
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421 | Create; |
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422 | }; |
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423 | |
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424 | ///@} |
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425 | |
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426 | protected: |
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427 | |
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428 | DagShortestPath() {} |
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429 | |
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430 | public: |
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431 | |
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432 | /// \brief Constructor. |
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433 | /// |
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434 | /// \param _graph the graph the algorithm will run on. |
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435 | /// \param _length the length map used by the algorithm. |
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436 | DagShortestPath(const Graph& _graph, const LengthMap& _length) : |
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437 | graph(&_graph), length(&_length), |
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438 | _pred(0), local_pred(false), |
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439 | _dist(0), local_dist(false){} |
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440 | |
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441 | /// \brief Constructor with node weight map. |
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442 | /// |
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443 | /// \param _graph the graph the algorithm will run on. |
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444 | /// \param _length the length map used by the algorithm. |
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445 | /// The NodeMap _length will be used as the weight map. |
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446 | /// Each edge will have the weight of its target node. |
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447 | DagShortestPath(const Graph& _graph, const WeightMap& _length) : |
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448 | graph(&_graph), |
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449 | _pred(0), local_pred(false), |
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450 | _dist(0), local_dist(false){ |
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451 | length=new LengthMap(_graph); |
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452 | _dist=new DistMap(_graph); |
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453 | for(EdgeIt eit(_graph);eit!=INVALID;++eit) |
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454 | (const_cast<LengthMap*>(length))->set(eit,_length[_graph.target(eit)]); |
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455 | } |
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456 | |
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457 | ///Destructor. |
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458 | ~DagShortestPath() { |
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459 | if(local_pred) delete _pred; |
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460 | if(local_dist) delete _dist; |
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461 | } |
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462 | |
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463 | /// \brief Sets the length map. |
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464 | /// |
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465 | /// Sets the length map. |
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466 | /// \return \c (*this) |
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467 | DagShortestPath &lengthMap(const LengthMap &m) { |
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468 | length = &m; |
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469 | return *this; |
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470 | } |
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471 | |
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472 | /// \brief Sets the map storing the predecessor edges. |
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473 | /// |
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474 | /// Sets the map storing the predecessor edges. |
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475 | /// If you don't use this function before calling \ref run(), |
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476 | /// it will allocate one. The destuctor deallocates this |
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477 | /// automatically allocated map, of course. |
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478 | /// \return \c (*this) |
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479 | DagShortestPath &predMap(PredMap &m) { |
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480 | if(local_pred) { |
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481 | delete _pred; |
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482 | local_pred=false; |
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483 | } |
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484 | _pred = &m; |
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485 | return *this; |
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486 | } |
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487 | |
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488 | /// \brief Sets the map storing the distances calculated by the algorithm. |
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489 | /// |
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490 | /// Sets the map storing the distances calculated by the algorithm. |
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491 | /// If you don't use this function before calling \ref run(), |
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492 | /// it will allocate one. The destuctor deallocates this |
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493 | /// automatically allocated map, of course. |
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494 | /// \return \c (*this) |
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495 | DagShortestPath &distMap(DistMap &m) { |
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496 | if(local_dist) { |
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497 | delete _dist; |
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498 | local_dist=false; |
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499 | } |
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500 | _dist = &m; |
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501 | return *this; |
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502 | } |
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503 | |
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504 | /// \name Execution control |
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505 | /// The simplest way to execute the algorithm is to use |
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506 | /// one of the member functions called \c run(...) |
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507 | /// \n |
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508 | /// If you need more control on the execution, |
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509 | /// first you must call \ref init(...), then you can add several source |
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510 | /// nodes with \ref addSource(). |
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511 | /// Finally \ref start() will perform the actual path computation. |
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512 | /// Some functions have an alternative form (\ref checkedInit(...), |
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513 | /// \ref checkedRun(...)) which also verifies if the graph given in the |
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514 | /// constructor is a dag. |
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515 | |
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516 | ///@{ |
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517 | |
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518 | /// \brief Initializes the internal data structures. |
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519 | /// |
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520 | /// Initializes the internal data structures. |
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521 | void init(const Value value = OperationTraits::infinity()) { |
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522 | typedef typename Graph::template NodeMap<int> NodeOrderMap; |
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523 | _process_step=0; |
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524 | NodeOrderMap node_order(*graph); |
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525 | topologicalSort(*graph,node_order); |
---|
526 | _node_order.resize(countNodes(*graph),INVALID); |
---|
527 | create_maps(); |
---|
528 | for (NodeIt it(*graph); it != INVALID; ++it) { |
---|
529 | _node_order[node_order[it]]=it; |
---|
530 | _pred->set(it, INVALID); |
---|
531 | _dist->set(it, value); |
---|
532 | } |
---|
533 | } |
---|
534 | |
---|
535 | /// \brief Initializes the internal data structures |
---|
536 | /// with a given topological sort (NodeMap). |
---|
537 | /// |
---|
538 | /// Initializes the internal data structures |
---|
539 | /// with a given topological sort (NodeMap). |
---|
540 | void init(const typename Graph::template NodeMap<int>& node_order, |
---|
541 | const Value value = OperationTraits::infinity()) { |
---|
542 | _process_step=0; |
---|
543 | _node_order.resize(countNodes(*graph),INVALID); |
---|
544 | create_maps(); |
---|
545 | for (NodeIt it(*graph); it != INVALID; ++it) { |
---|
546 | _node_order[node_order[it]]=it; |
---|
547 | _pred->set(it, INVALID); |
---|
548 | _dist->set(it, value); |
---|
549 | } |
---|
550 | } |
---|
551 | |
---|
552 | /// \brief Initializes the internal data structures |
---|
553 | /// with a given topological sort (std::vector). |
---|
554 | /// |
---|
555 | /// Initializes the internal data structures |
---|
556 | /// with a given topological sort (std::vector). |
---|
557 | void init(const std::vector<Node>& node_order, |
---|
558 | const Value value = OperationTraits::infinity()) { |
---|
559 | _process_step=0; |
---|
560 | _node_order=node_order; |
---|
561 | create_maps(); |
---|
562 | for (NodeIt it(*graph); it != INVALID; ++it) { |
---|
563 | _pred->set(it, INVALID); |
---|
564 | _dist->set(it, value); |
---|
565 | } |
---|
566 | } |
---|
567 | |
---|
568 | /// \brief Initializes the internal data structures. It also checks if the graph is dag. |
---|
569 | /// |
---|
570 | /// Initializes the internal data structures. It also checks if the graph is dag. |
---|
571 | /// \return true if the graph (given in the constructor) is dag, false otherwise. |
---|
572 | bool checkedInit(const Value value = OperationTraits::infinity()) { |
---|
573 | typedef typename Graph::template NodeMap<int> NodeOrderMap; |
---|
574 | NodeOrderMap node_order(*graph); |
---|
575 | if(!checkedTopologicalSort(*graph,node_order))return false; |
---|
576 | init(node_order,value); |
---|
577 | return true; |
---|
578 | } |
---|
579 | |
---|
580 | /// \brief Initializes the internal data structures with a given |
---|
581 | /// topological sort (NodeMap). It also checks if the graph is dag. |
---|
582 | /// |
---|
583 | /// Initializes the internal data structures with a given |
---|
584 | /// topological sort (NodeMap). It also checks if the graph is dag. |
---|
585 | /// \return true if the graph (given in the constructor) is dag, false otherwise. |
---|
586 | bool checkedInit(const typename Graph::template NodeMap<int>& node_order, |
---|
587 | const Value value = OperationTraits::infinity()) { |
---|
588 | for(NodeIt it(*graph);it!=INVALID;++it){ |
---|
589 | for(OutEdgeIt oeit(*graph,it);oeit!=INVALID;++oeit){ |
---|
590 | if(node_order[graph->target(oeit)]<node_order[it])return false; |
---|
591 | } |
---|
592 | } |
---|
593 | init(node_order,value); |
---|
594 | return true; |
---|
595 | } |
---|
596 | |
---|
597 | /// \brief Initializes the internal data structures with a given |
---|
598 | /// topological sort (std::vector). It also checks if the graph is dag. |
---|
599 | /// |
---|
600 | /// Initializes the internal data structures with a given |
---|
601 | /// topological sort (std::vector). It also checks if the graph is dag. |
---|
602 | /// \return true if the graph (given in the constructor) is dag, false otherwise. |
---|
603 | bool checkedInit(const std::vector<Node>& node_order, |
---|
604 | const Value value = OperationTraits::infinity()) { |
---|
605 | typedef typename Graph::template NodeMap<bool> BoolNodeMap; |
---|
606 | BoolNodeMap _processed(*graph,false); |
---|
607 | for(unsigned int i=0;i<_node_order.size();++i){ |
---|
608 | _processed[node_order[i]]=true; |
---|
609 | for(OutEdgeIt oeit(*graph,node_order[i]);oeit!=INVALID;++oeit){ |
---|
610 | if(_processed[graph->target(oeit)])return false; |
---|
611 | } |
---|
612 | } |
---|
613 | init(node_order,value); |
---|
614 | return true; |
---|
615 | } |
---|
616 | |
---|
617 | /// \brief Adds a new source node. |
---|
618 | /// |
---|
619 | /// The optional second parameter is the initial distance of the node. |
---|
620 | /// It just sets the distance of the node to the given value. |
---|
621 | void addSource(Node source, Value dst = OperationTraits::zero()) { |
---|
622 | if((*_dist)[source] != dst){ |
---|
623 | _dist->set(source, dst); |
---|
624 | } |
---|
625 | } |
---|
626 | |
---|
627 | /// \brief Executes one step from the dag shortest path algorithm. |
---|
628 | /// |
---|
629 | /// If the algoritm calculated the distances in the previous step |
---|
630 | /// strictly for all at most k length paths then it will calculate the |
---|
631 | /// distances strictly for all at most k + 1 length paths. With k |
---|
632 | /// iteration this function calculates the at most k length paths. |
---|
633 | ///\pre the queue is not empty |
---|
634 | ///\return the currently processed node |
---|
635 | Node processNextNode() { |
---|
636 | if(reached(_node_order[_process_step])){ |
---|
637 | for (OutEdgeIt it(*graph, _node_order[_process_step]); it != INVALID; ++it) { |
---|
638 | Node target = graph->target(it); |
---|
639 | Value relaxed = |
---|
640 | OperationTraits::plus((*_dist)[_node_order[_process_step]], (*length)[it]); |
---|
641 | if (OperationTraits::less(relaxed, (*_dist)[target])) { |
---|
642 | _pred->set(target, it); |
---|
643 | _dist->set(target, relaxed); |
---|
644 | } |
---|
645 | } |
---|
646 | } |
---|
647 | ++_process_step; |
---|
648 | return _node_order[_process_step-1]; |
---|
649 | } |
---|
650 | |
---|
651 | ///\brief Returns \c false if there are nodes |
---|
652 | ///to be processed in the queue |
---|
653 | /// |
---|
654 | ///Returns \c false if there are nodes |
---|
655 | ///to be processed in the queue |
---|
656 | bool emptyQueue() { return _node_order.size()-1==_process_step; } |
---|
657 | |
---|
658 | ///\brief Returns the number of the nodes to be processed. |
---|
659 | /// |
---|
660 | ///Returns the number of the nodes to be processed in the queue. |
---|
661 | int queueSize() { return _node_order.size()-1-_process_step; } |
---|
662 | |
---|
663 | /// \brief Executes the algorithm. |
---|
664 | /// |
---|
665 | /// \pre init() must be called and at least one node should be added |
---|
666 | /// with addSource() before using this function. |
---|
667 | /// |
---|
668 | /// This method runs the %DagShortestPath algorithm from the root node(s) |
---|
669 | /// in order to compute the shortest path to each node. The algorithm |
---|
670 | /// computes |
---|
671 | /// - The shortest path tree. |
---|
672 | /// - The distance of each node from the root(s). |
---|
673 | void start() { |
---|
674 | while(!emptyQueue()) { |
---|
675 | processNextNode(); |
---|
676 | } |
---|
677 | } |
---|
678 | |
---|
679 | /// \brief Runs %DagShortestPath algorithm from node \c s. |
---|
680 | /// |
---|
681 | /// This method runs the %DagShortestPath algorithm from a root node \c s |
---|
682 | /// in order to compute the shortest path to each node. The algorithm |
---|
683 | /// computes |
---|
684 | /// - The shortest path tree. |
---|
685 | /// - The distance of each node from the root. |
---|
686 | /// |
---|
687 | /// \note d.run(s) is just a shortcut of the following code. |
---|
688 | ///\code |
---|
689 | /// d.init(); |
---|
690 | /// d.addSource(s); |
---|
691 | /// d.start(); |
---|
692 | ///\endcode |
---|
693 | void run(Node s) { |
---|
694 | init(); |
---|
695 | addSource(s); |
---|
696 | start(); |
---|
697 | } |
---|
698 | |
---|
699 | /// \brief Runs %DagShortestPath algorithm from node \c s. |
---|
700 | /// It also checks if the graph is a dag. |
---|
701 | /// |
---|
702 | /// This method runs the %DagShortestPath algorithm from a root node \c s |
---|
703 | /// in order to compute the shortest path to each node. The algorithm |
---|
704 | /// computes |
---|
705 | /// - The shortest path tree. |
---|
706 | /// - The distance of each node from the root. |
---|
707 | /// The algorithm checks if the graph given int the constructor is a dag. |
---|
708 | bool checkedRun(Node s) { |
---|
709 | if(!checkedInit())return false; |
---|
710 | addSource(s); |
---|
711 | start(); |
---|
712 | return true; |
---|
713 | } |
---|
714 | |
---|
715 | ///@} |
---|
716 | |
---|
717 | /// \name Query Functions |
---|
718 | /// The result of the %DagShortestPath algorithm can be obtained using these |
---|
719 | /// functions.\n |
---|
720 | /// Before the use of these functions, |
---|
721 | /// either run() or start() must be called. |
---|
722 | |
---|
723 | ///@{ |
---|
724 | |
---|
725 | /// \brief Copies the shortest path to \c t into \c p |
---|
726 | /// |
---|
727 | /// This function copies the shortest path to \c t into \c p. |
---|
728 | /// If it \c t is a source itself or unreachable, then it does not |
---|
729 | /// alter \c p. |
---|
730 | /// |
---|
731 | /// \return Returns \c true if a path to \c t was actually copied to \c p, |
---|
732 | /// \c false otherwise. |
---|
733 | /// \sa DirPath |
---|
734 | template <typename Path> |
---|
735 | bool getPath(Path &p, Node t) { |
---|
736 | if(reached(t)) { |
---|
737 | p.clear(); |
---|
738 | typename Path::Builder b(p); |
---|
739 | for(b.setStartNode(t);predEdge(t)!=INVALID;t=predNode(t)) |
---|
740 | b.pushFront(predEdge(t)); |
---|
741 | b.commit(); |
---|
742 | return true; |
---|
743 | } |
---|
744 | return false; |
---|
745 | } |
---|
746 | |
---|
747 | /// \brief The distance of a node from the root. |
---|
748 | /// |
---|
749 | /// Returns the distance of a node from the root. |
---|
750 | /// \pre \ref run() must be called before using this function. |
---|
751 | /// \warning If node \c v in unreachable from the root the return value |
---|
752 | /// of this funcion is undefined. |
---|
753 | Value dist(Node v) const { return (*_dist)[v]; } |
---|
754 | |
---|
755 | /// \brief Returns the 'previous edge' of the shortest path tree. |
---|
756 | /// |
---|
757 | /// For a node \c v it returns the 'previous edge' of the shortest path |
---|
758 | /// tree, i.e. it returns the last edge of a shortest path from the root |
---|
759 | /// to \c v. It is \ref INVALID if \c v is unreachable from the root or |
---|
760 | /// if \c v=s. The shortest path tree used here is equal to the shortest |
---|
761 | /// path tree used in \ref predNode(). |
---|
762 | /// \pre \ref run() must be called before using |
---|
763 | /// this function. |
---|
764 | Edge predEdge(Node v) const { return (*_pred)[v]; } |
---|
765 | |
---|
766 | /// \brief Returns the 'previous node' of the shortest path tree. |
---|
767 | /// |
---|
768 | /// For a node \c v it returns the 'previous node' of the shortest path |
---|
769 | /// tree, i.e. it returns the last but one node from a shortest path from |
---|
770 | /// the root to \c /v. It is INVALID if \c v is unreachable from the root |
---|
771 | /// or if \c v=s. The shortest path tree used here is equal to the |
---|
772 | /// shortest path tree used in \ref predEdge(). \pre \ref run() must be |
---|
773 | /// called before using this function. |
---|
774 | Node predNode(Node v) const { |
---|
775 | return (*_pred)[v] == INVALID ? INVALID : graph->source((*_pred)[v]); |
---|
776 | } |
---|
777 | |
---|
778 | /// \brief Returns a reference to the NodeMap of distances. |
---|
779 | /// |
---|
780 | /// Returns a reference to the NodeMap of distances. \pre \ref run() must |
---|
781 | /// be called before using this function. |
---|
782 | const DistMap &distMap() const { return *_dist;} |
---|
783 | |
---|
784 | /// \brief Returns a reference to the shortest path tree map. |
---|
785 | /// |
---|
786 | /// Returns a reference to the NodeMap of the edges of the |
---|
787 | /// shortest path tree. |
---|
788 | /// \pre \ref run() must be called before using this function. |
---|
789 | const PredMap &predMap() const { return *_pred; } |
---|
790 | |
---|
791 | /// \brief Checks if a node is reachable from the root. |
---|
792 | /// |
---|
793 | /// Returns \c true if \c v is reachable from the root. |
---|
794 | /// \pre \ref run() must be called before using this function. |
---|
795 | /// |
---|
796 | bool reached(Node v) { return (*_dist)[v] != OperationTraits::infinity(); } |
---|
797 | |
---|
798 | ///@} |
---|
799 | }; |
---|
800 | |
---|
801 | /// \brief Default traits class of DagShortestPath function. |
---|
802 | /// |
---|
803 | /// Default traits class of DagShortestPath function. |
---|
804 | /// \param _Graph Graph type. |
---|
805 | /// \param _LengthMap Type of length map. |
---|
806 | template <typename _Graph, typename _LengthMap> |
---|
807 | struct DagShortestPathWizardDefaultTraits { |
---|
808 | /// \brief The graph type the algorithm runs on. |
---|
809 | typedef _Graph Graph; |
---|
810 | |
---|
811 | /// \brief The type of the map that stores the edge lengths. |
---|
812 | /// |
---|
813 | /// The type of the map that stores the edge lengths. |
---|
814 | /// It must meet the \ref concept::ReadMap "ReadMap" concept. |
---|
815 | typedef _LengthMap LengthMap; |
---|
816 | |
---|
817 | /// \brief The value type of the length map. |
---|
818 | typedef typename _LengthMap::Value Value; |
---|
819 | |
---|
820 | /// \brief Operation traits for dag shortest path algorithm. |
---|
821 | /// |
---|
822 | /// It defines the infinity type on the given Value type |
---|
823 | /// and the used operation. |
---|
824 | /// \see DagShortestPathDefaultOperationTraits |
---|
825 | typedef DagShortestPathDefaultOperationTraits<Value> OperationTraits; |
---|
826 | |
---|
827 | /// \brief The type of the map that stores the last |
---|
828 | /// edges of the shortest paths. |
---|
829 | /// |
---|
830 | /// The type of the map that stores the last |
---|
831 | /// edges of the shortest paths. |
---|
832 | /// It must meet the \ref concept::WriteMap "WriteMap" concept. |
---|
833 | typedef NullMap <typename _Graph::Node,typename _Graph::Edge> PredMap; |
---|
834 | |
---|
835 | /// \brief Instantiates a PredMap. |
---|
836 | /// |
---|
837 | /// This function instantiates a \ref PredMap. |
---|
838 | static PredMap *createPredMap(const _Graph &) { |
---|
839 | return new PredMap(); |
---|
840 | } |
---|
841 | /// \brief The type of the map that stores the dists of the nodes. |
---|
842 | /// |
---|
843 | /// The type of the map that stores the dists of the nodes. |
---|
844 | /// It must meet the \ref concept::WriteMap "WriteMap" concept. |
---|
845 | typedef NullMap<typename Graph::Node, Value> DistMap; |
---|
846 | /// \brief Instantiates a DistMap. |
---|
847 | /// |
---|
848 | /// This function instantiates a \ref DistMap. |
---|
849 | static DistMap *createDistMap(const _Graph &) { |
---|
850 | return new DistMap(); |
---|
851 | } |
---|
852 | }; |
---|
853 | |
---|
854 | /// \brief Default traits used by \ref DagShortestPathWizard |
---|
855 | /// |
---|
856 | /// To make it easier to use DagShortestPath algorithm |
---|
857 | /// we have created a wizard class. |
---|
858 | /// This \ref DagShortestPathWizard class needs default traits, |
---|
859 | /// as well as the \ref DagShortestPath class. |
---|
860 | /// The \ref DagShortestPathWizardBase is a class to be the default traits of the |
---|
861 | /// \ref DagShortestPathWizard class. |
---|
862 | /// \todo More named parameters are required... |
---|
863 | template<class _Graph,class _LengthMap> |
---|
864 | class DagShortestPathWizardBase |
---|
865 | : public DagShortestPathWizardDefaultTraits<_Graph,_LengthMap> { |
---|
866 | |
---|
867 | typedef DagShortestPathWizardDefaultTraits<_Graph,_LengthMap> Base; |
---|
868 | protected: |
---|
869 | /// Type of the nodes in the graph. |
---|
870 | typedef typename Base::Graph::Node Node; |
---|
871 | |
---|
872 | /// Pointer to the underlying graph. |
---|
873 | void *_graph; |
---|
874 | /// Pointer to the length map |
---|
875 | void *_length; |
---|
876 | ///Pointer to the map of predecessors edges. |
---|
877 | void *_pred; |
---|
878 | ///Pointer to the map of distances. |
---|
879 | void *_dist; |
---|
880 | ///Pointer to the source node. |
---|
881 | Node _source; |
---|
882 | |
---|
883 | public: |
---|
884 | /// Constructor. |
---|
885 | |
---|
886 | /// This constructor does not require parameters, therefore it initiates |
---|
887 | /// all of the attributes to default values (0, INVALID). |
---|
888 | DagShortestPathWizardBase() : _graph(0), _length(0), _pred(0), |
---|
889 | _dist(0), _source(INVALID) {} |
---|
890 | |
---|
891 | /// Constructor. |
---|
892 | |
---|
893 | /// This constructor requires some parameters, |
---|
894 | /// listed in the parameters list. |
---|
895 | /// Others are initiated to 0. |
---|
896 | /// \param graph is the initial value of \ref _graph |
---|
897 | /// \param length is the initial value of \ref _length |
---|
898 | /// \param source is the initial value of \ref _source |
---|
899 | DagShortestPathWizardBase(const _Graph& graph, |
---|
900 | const _LengthMap& length, |
---|
901 | Node source = INVALID) : |
---|
902 | _graph((void *)&graph), _length((void *)&length), _pred(0), |
---|
903 | _dist(0), _source(source) {} |
---|
904 | |
---|
905 | }; |
---|
906 | |
---|
907 | /// A class to make the usage of DagShortestPath algorithm easier |
---|
908 | |
---|
909 | /// This class is created to make it easier to use DagShortestPath algorithm. |
---|
910 | /// It uses the functions and features of the plain \ref DagShortestPath, |
---|
911 | /// but it is much simpler to use it. |
---|
912 | /// |
---|
913 | /// Simplicity means that the way to change the types defined |
---|
914 | /// in the traits class is based on functions that returns the new class |
---|
915 | /// and not on templatable built-in classes. |
---|
916 | /// When using the plain \ref DagShortestPath |
---|
917 | /// the new class with the modified type comes from |
---|
918 | /// the original class by using the :: |
---|
919 | /// operator. In the case of \ref DagShortestPathWizard only |
---|
920 | /// a function have to be called and it will |
---|
921 | /// return the needed class. |
---|
922 | /// |
---|
923 | /// It does not have own \ref run method. When its \ref run method is called |
---|
924 | /// it initiates a plain \ref DagShortestPath class, and calls the \ref |
---|
925 | /// DagShortestPath::run() method of it. |
---|
926 | template<class _Traits> |
---|
927 | class DagShortestPathWizard : public _Traits { |
---|
928 | typedef _Traits Base; |
---|
929 | |
---|
930 | ///The type of the underlying graph. |
---|
931 | typedef typename _Traits::Graph Graph; |
---|
932 | |
---|
933 | typedef typename Graph::Node Node; |
---|
934 | typedef typename Graph::NodeIt NodeIt; |
---|
935 | typedef typename Graph::Edge Edge; |
---|
936 | typedef typename Graph::OutEdgeIt EdgeIt; |
---|
937 | |
---|
938 | ///The type of the map that stores the edge lengths. |
---|
939 | typedef typename _Traits::LengthMap LengthMap; |
---|
940 | |
---|
941 | ///The type of the length of the edges. |
---|
942 | typedef typename LengthMap::Value Value; |
---|
943 | |
---|
944 | ///\brief The type of the map that stores the last |
---|
945 | ///edges of the shortest paths. |
---|
946 | typedef typename _Traits::PredMap PredMap; |
---|
947 | |
---|
948 | ///The type of the map that stores the dists of the nodes. |
---|
949 | typedef typename _Traits::DistMap DistMap; |
---|
950 | |
---|
951 | public: |
---|
952 | /// Constructor. |
---|
953 | DagShortestPathWizard() : _Traits() {} |
---|
954 | |
---|
955 | /// \brief Constructor that requires parameters. |
---|
956 | /// |
---|
957 | /// Constructor that requires parameters. |
---|
958 | /// These parameters will be the default values for the traits class. |
---|
959 | DagShortestPathWizard(const Graph& graph, const LengthMap& length, |
---|
960 | Node source = INVALID) |
---|
961 | : _Traits(graph, length, source) {} |
---|
962 | |
---|
963 | /// \brief Copy constructor |
---|
964 | DagShortestPathWizard(const _Traits &b) : _Traits(b) {} |
---|
965 | |
---|
966 | ~DagShortestPathWizard() {} |
---|
967 | |
---|
968 | /// \brief Runs DagShortestPath algorithm from a given node. |
---|
969 | /// |
---|
970 | /// Runs DagShortestPath algorithm from a given node. |
---|
971 | /// The node can be given by the \ref source function. |
---|
972 | void run() { |
---|
973 | if(Base::_source == INVALID) throw UninitializedParameter(); |
---|
974 | DagShortestPath<Graph,LengthMap,_Traits> |
---|
975 | bf(*(Graph*)Base::_graph, *(LengthMap*)Base::_length); |
---|
976 | if (Base::_pred) bf.predMap(*(PredMap*)Base::_pred); |
---|
977 | if (Base::_dist) bf.distMap(*(DistMap*)Base::_dist); |
---|
978 | bf.run(Base::_source); |
---|
979 | } |
---|
980 | |
---|
981 | /// \brief Runs DagShortestPath algorithm from the given node. |
---|
982 | /// |
---|
983 | /// Runs DagShortestPath algorithm from the given node. |
---|
984 | /// \param source is the given source. |
---|
985 | void run(Node source) { |
---|
986 | Base::_source = source; |
---|
987 | run(); |
---|
988 | } |
---|
989 | |
---|
990 | template<class T> |
---|
991 | struct DefPredMapBase : public Base { |
---|
992 | typedef T PredMap; |
---|
993 | static PredMap *createPredMap(const Graph &) { return 0; }; |
---|
994 | DefPredMapBase(const _Traits &b) : _Traits(b) {} |
---|
995 | }; |
---|
996 | |
---|
997 | ///\brief \ref named-templ-param "Named parameter" |
---|
998 | ///function for setting PredMap type |
---|
999 | /// |
---|
1000 | /// \ref named-templ-param "Named parameter" |
---|
1001 | ///function for setting PredMap type |
---|
1002 | /// |
---|
1003 | template<class T> |
---|
1004 | DagShortestPathWizard<DefPredMapBase<T> > predMap(const T &t) |
---|
1005 | { |
---|
1006 | Base::_pred=(void *)&t; |
---|
1007 | return DagShortestPathWizard<DefPredMapBase<T> >(*this); |
---|
1008 | } |
---|
1009 | |
---|
1010 | template<class T> |
---|
1011 | struct DefDistMapBase : public Base { |
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1012 | typedef T DistMap; |
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1013 | static DistMap *createDistMap(const Graph &) { return 0; }; |
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1014 | DefDistMapBase(const _Traits &b) : _Traits(b) {} |
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1015 | }; |
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1016 | |
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1017 | ///\brief \ref named-templ-param "Named parameter" |
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1018 | ///function for setting DistMap type |
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1019 | /// |
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1020 | /// \ref named-templ-param "Named parameter" |
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1021 | ///function for setting DistMap type |
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1022 | /// |
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1023 | template<class T> |
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1024 | DagShortestPathWizard<DefDistMapBase<T> > distMap(const T &t) { |
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1025 | Base::_dist=(void *)&t; |
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1026 | return DagShortestPathWizard<DefDistMapBase<T> >(*this); |
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1027 | } |
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1028 | |
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1029 | template<class T> |
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1030 | struct DefOperationTraitsBase : public Base { |
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1031 | typedef T OperationTraits; |
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1032 | DefOperationTraitsBase(const _Traits &b) : _Traits(b) {} |
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1033 | }; |
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1034 | |
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1035 | ///\brief \ref named-templ-param "Named parameter" |
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1036 | ///function for setting OperationTraits type |
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1037 | /// |
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1038 | /// \ref named-templ-param "Named parameter" |
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1039 | ///function for setting OperationTraits type |
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1040 | /// |
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1041 | template<class T> |
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1042 | DagShortestPathWizard<DefOperationTraitsBase<T> > distMap() { |
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1043 | return DagShortestPathWizard<DefDistMapBase<T> >(*this); |
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1044 | } |
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1045 | |
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1046 | /// \brief Sets the source node, from which the DagShortestPath algorithm runs. |
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1047 | /// |
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1048 | /// Sets the source node, from which the DagShortestPath algorithm runs. |
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1049 | /// \param source is the source node. |
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1050 | DagShortestPathWizard<_Traits>& source(Node source) { |
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1051 | Base::_source = source; |
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1052 | return *this; |
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1053 | } |
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1054 | |
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1055 | }; |
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1056 | |
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1057 | /// \brief Function type interface for DagShortestPath algorithm. |
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1058 | /// |
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1059 | /// \ingroup flowalgs |
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1060 | /// Function type interface for DagShortestPath algorithm. |
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1061 | /// |
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1062 | /// This function also has several \ref named-templ-func-param |
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1063 | /// "named parameters", they are declared as the members of class |
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1064 | /// \ref DagShortestPathWizard. |
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1065 | /// The following |
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1066 | /// example shows how to use these parameters. |
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1067 | ///\code |
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1068 | /// dagShortestPath(g,length,source).predMap(preds).run(); |
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1069 | ///\endcode |
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1070 | /// \warning Don't forget to put the \ref DagShortestPathWizard::run() "run()" |
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1071 | /// to the end of the parameter list. |
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1072 | /// \sa DagShortestPathWizard |
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1073 | /// \sa DagShortestPath |
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1074 | template<class _Graph, class _LengthMap> |
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1075 | DagShortestPathWizard<DagShortestPathWizardBase<_Graph,_LengthMap> > |
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1076 | dagShortestPath(const _Graph& graph, |
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1077 | const _LengthMap& length, |
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1078 | typename _Graph::Node source = INVALID) { |
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1079 | return DagShortestPathWizard<DagShortestPathWizardBase<_Graph,_LengthMap> > |
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1080 | (graph, length, source); |
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1081 | } |
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1082 | |
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1083 | } //END OF NAMESPACE LEMON |
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1084 | |
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1085 | #endif |
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1086 | |
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