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) 2003-2007 |
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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_UNION_FIND_H |
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20 | #define LEMON_UNION_FIND_H |
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21 | |
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22 | //!\ingroup auxdat |
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23 | //!\file |
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24 | //!\brief Union-Find data structures. |
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25 | //! |
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26 | |
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27 | #include <vector> |
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28 | #include <list> |
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29 | #include <utility> |
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30 | #include <algorithm> |
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31 | |
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32 | #include <lemon/bits/invalid.h> |
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33 | |
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34 | namespace lemon { |
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35 | |
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36 | /// \ingroup auxdat |
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37 | /// |
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38 | /// \brief A \e Union-Find data structure implementation |
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39 | /// |
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40 | /// The class implements the \e Union-Find data structure. |
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41 | /// The union operation uses rank heuristic, while |
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42 | /// the find operation uses path compression. |
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43 | /// This is a very simple but efficient implementation, providing |
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44 | /// only four methods: join (union), find, insert and size. |
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45 | /// For more features see the \ref UnionFindEnum class. |
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46 | /// |
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47 | /// It is primarily used in Kruskal algorithm for finding minimal |
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48 | /// cost spanning tree in a graph. |
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49 | /// \sa kruskal() |
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50 | /// |
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51 | /// \pre You need to add all the elements by the \ref insert() |
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52 | /// method. |
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53 | template <typename _ItemIntMap> |
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54 | class UnionFind { |
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55 | public: |
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56 | |
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57 | typedef _ItemIntMap ItemIntMap; |
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58 | typedef typename ItemIntMap::Key Item; |
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59 | |
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60 | private: |
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61 | // If the items vector stores negative value for an item then |
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62 | // that item is root item and it has -items[it] component size. |
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63 | // Else the items[it] contains the index of the parent. |
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64 | std::vector<int> items; |
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65 | ItemIntMap& index; |
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66 | |
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67 | bool rep(int idx) const { |
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68 | return items[idx] < 0; |
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69 | } |
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70 | |
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71 | int repIndex(int idx) const { |
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72 | int k = idx; |
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73 | while (!rep(k)) { |
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74 | k = items[k] ; |
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75 | } |
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76 | while (idx != k) { |
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77 | int next = items[idx]; |
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78 | const_cast<int&>(items[idx]) = k; |
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79 | idx = next; |
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80 | } |
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81 | return k; |
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82 | } |
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83 | |
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84 | public: |
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85 | |
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86 | /// \brief Constructor |
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87 | /// |
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88 | /// Constructor of the UnionFind class. You should give an item to |
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89 | /// integer map which will be used from the data structure. If you |
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90 | /// modify directly this map that may cause segmentation fault, |
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91 | /// invalid data structure, or infinite loop when you use again |
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92 | /// the union-find. |
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93 | UnionFind(ItemIntMap& m) : index(m) {} |
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94 | |
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95 | /// \brief Returns the index of the element's component. |
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96 | /// |
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97 | /// The method returns the index of the element's component. |
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98 | /// This is an integer between zero and the number of inserted elements. |
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99 | /// |
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100 | int find(const Item& a) { |
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101 | return repIndex(index[a]); |
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102 | } |
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103 | |
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104 | /// \brief Clears the union-find data structure |
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105 | /// |
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106 | /// Erase each item from the data structure. |
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107 | void clear() { |
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108 | items.clear(); |
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109 | } |
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110 | |
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111 | /// \brief Inserts a new element into the structure. |
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112 | /// |
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113 | /// This method inserts a new element into the data structure. |
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114 | /// |
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115 | /// The method returns the index of the new component. |
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116 | int insert(const Item& a) { |
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117 | int n = items.size(); |
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118 | items.push_back(-1); |
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119 | index.set(a,n); |
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120 | return n; |
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121 | } |
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122 | |
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123 | /// \brief Joining the components of element \e a and element \e b. |
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124 | /// |
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125 | /// This is the \e union operation of the Union-Find structure. |
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126 | /// Joins the component of element \e a and component of |
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127 | /// element \e b. If \e a and \e b are in the same component then |
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128 | /// it returns false otherwise it returns true. |
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129 | bool join(const Item& a, const Item& b) { |
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130 | int ka = repIndex(index[a]); |
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131 | int kb = repIndex(index[b]); |
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132 | |
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133 | if ( ka == kb ) |
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134 | return false; |
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135 | |
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136 | if (items[ka] < items[kb]) { |
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137 | items[ka] += items[kb]; |
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138 | items[kb] = ka; |
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139 | } else { |
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140 | items[kb] += items[ka]; |
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141 | items[ka] = kb; |
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142 | } |
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143 | return true; |
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144 | } |
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145 | |
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146 | /// \brief Returns the size of the component of element \e a. |
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147 | /// |
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148 | /// Returns the size of the component of element \e a. |
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149 | int size(const Item& a) { |
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150 | int k = repIndex(index[a]); |
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151 | return - items[k]; |
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152 | } |
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153 | |
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154 | }; |
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155 | |
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156 | /// \ingroup auxdat |
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157 | /// |
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158 | /// \brief A \e Union-Find data structure implementation which |
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159 | /// is able to enumerate the components. |
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160 | /// |
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161 | /// The class implements a \e Union-Find data structure |
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162 | /// which is able to enumerate the components and the items in |
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163 | /// a component. If you don't need this feature then perhaps it's |
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164 | /// better to use the \ref UnionFind class which is more efficient. |
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165 | /// |
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166 | /// The union operation uses rank heuristic, while |
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167 | /// the find operation uses path compression. |
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168 | /// |
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169 | /// \pre You need to add all the elements by the \ref insert() |
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170 | /// method. |
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171 | /// |
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172 | template <typename _ItemIntMap> |
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173 | class UnionFindEnum { |
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174 | public: |
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175 | |
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176 | typedef _ItemIntMap ItemIntMap; |
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177 | typedef typename ItemIntMap::Key Item; |
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178 | |
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179 | private: |
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180 | |
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181 | ItemIntMap& index; |
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182 | |
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183 | // If the parent stores negative value for an item then that item |
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184 | // is root item and it has ~(items[it].parent) component id. Else |
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185 | // the items[it].parent contains the index of the parent. |
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186 | // |
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187 | // The \c next and \c prev provides the double-linked |
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188 | // cyclic list of one component's items. |
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189 | struct ItemT { |
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190 | int parent; |
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191 | Item item; |
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192 | |
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193 | int next, prev; |
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194 | }; |
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195 | |
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196 | std::vector<ItemT> items; |
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197 | int firstFreeItem; |
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198 | |
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199 | struct ClassT { |
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200 | int size; |
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201 | int firstItem; |
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202 | int next, prev; |
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203 | }; |
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204 | |
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205 | std::vector<ClassT> classes; |
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206 | int firstClass, firstFreeClass; |
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207 | |
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208 | int newClass() { |
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209 | if (firstFreeClass == -1) { |
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210 | int cdx = classes.size(); |
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211 | classes.push_back(ClassT()); |
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212 | return cdx; |
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213 | } else { |
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214 | int cdx = firstFreeClass; |
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215 | firstFreeClass = classes[firstFreeClass].next; |
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216 | return cdx; |
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217 | } |
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218 | } |
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219 | |
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220 | int newItem() { |
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221 | if (firstFreeItem == -1) { |
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222 | int idx = items.size(); |
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223 | items.push_back(ItemT()); |
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224 | return idx; |
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225 | } else { |
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226 | int idx = firstFreeItem; |
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227 | firstFreeItem = items[firstFreeItem].next; |
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228 | return idx; |
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229 | } |
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230 | } |
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231 | |
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232 | |
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233 | bool rep(int idx) const { |
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234 | return items[idx].parent < 0; |
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235 | } |
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236 | |
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237 | int repIndex(int idx) const { |
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238 | int k = idx; |
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239 | while (!rep(k)) { |
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240 | k = items[k].parent; |
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241 | } |
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242 | while (idx != k) { |
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243 | int next = items[idx].parent; |
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244 | const_cast<int&>(items[idx].parent) = k; |
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245 | idx = next; |
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246 | } |
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247 | return k; |
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248 | } |
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249 | |
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250 | int classIndex(int idx) const { |
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251 | return ~(items[repIndex(idx)].parent); |
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252 | } |
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253 | |
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254 | void singletonItem(int idx) { |
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255 | items[idx].next = idx; |
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256 | items[idx].prev = idx; |
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257 | } |
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258 | |
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259 | void laceItem(int idx, int rdx) { |
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260 | items[idx].prev = rdx; |
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261 | items[idx].next = items[rdx].next; |
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262 | items[items[rdx].next].prev = idx; |
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263 | items[rdx].next = idx; |
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264 | } |
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265 | |
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266 | void unlaceItem(int idx) { |
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267 | items[items[idx].prev].next = items[idx].next; |
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268 | items[items[idx].next].prev = items[idx].prev; |
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269 | |
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270 | items[idx].next = firstFreeItem; |
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271 | firstFreeItem = idx; |
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272 | } |
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273 | |
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274 | void spliceItems(int ak, int bk) { |
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275 | items[items[ak].prev].next = bk; |
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276 | items[items[bk].prev].next = ak; |
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277 | int tmp = items[ak].prev; |
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278 | items[ak].prev = items[bk].prev; |
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279 | items[bk].prev = tmp; |
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280 | |
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281 | } |
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282 | |
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283 | void laceClass(int cls) { |
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284 | if (firstClass != -1) { |
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285 | classes[firstClass].prev = cls; |
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286 | } |
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287 | classes[cls].next = firstClass; |
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288 | classes[cls].prev = -1; |
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289 | firstClass = cls; |
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290 | } |
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291 | |
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292 | void unlaceClass(int cls) { |
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293 | if (classes[cls].prev != -1) { |
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294 | classes[classes[cls].prev].next = classes[cls].next; |
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295 | } else { |
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296 | firstClass = classes[cls].next; |
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297 | } |
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298 | if (classes[cls].next != -1) { |
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299 | classes[classes[cls].next].prev = classes[cls].prev; |
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300 | } |
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301 | |
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302 | classes[cls].next = firstFreeClass; |
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303 | firstFreeClass = cls; |
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304 | } |
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305 | |
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306 | public: |
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307 | |
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308 | UnionFindEnum(ItemIntMap& _index) |
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309 | : index(_index), items(), firstFreeItem(-1), |
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310 | firstClass(-1), firstFreeClass(-1) {} |
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311 | |
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312 | /// \brief Inserts the given element into a new component. |
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313 | /// |
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314 | /// This method creates a new component consisting only of the |
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315 | /// given element. |
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316 | /// |
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317 | int insert(const Item& item) { |
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318 | int idx = newItem(); |
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319 | |
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320 | index.set(item, idx); |
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321 | |
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322 | singletonItem(idx); |
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323 | items[idx].item = item; |
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324 | |
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325 | int cdx = newClass(); |
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326 | |
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327 | items[idx].parent = ~cdx; |
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328 | |
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329 | laceClass(cdx); |
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330 | classes[cdx].size = 1; |
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331 | classes[cdx].firstItem = idx; |
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332 | |
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333 | firstClass = cdx; |
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334 | |
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335 | return cdx; |
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336 | } |
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337 | |
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338 | /// \brief Inserts the given element into the component of the others. |
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339 | /// |
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340 | /// This methods inserts the element \e a into the component of the |
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341 | /// element \e comp. |
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342 | void insert(const Item& item, int cls) { |
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343 | int rdx = classes[cls].firstItem; |
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344 | int idx = newItem(); |
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345 | |
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346 | index.set(item, idx); |
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347 | |
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348 | laceItem(idx, rdx); |
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349 | |
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350 | items[idx].item = item; |
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351 | items[idx].parent = rdx; |
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352 | |
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353 | ++classes[~(items[rdx].parent)].size; |
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354 | } |
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355 | |
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356 | /// \brief Clears the union-find data structure |
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357 | /// |
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358 | /// Erase each item from the data structure. |
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359 | void clear() { |
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360 | items.clear(); |
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361 | firstClass = -1; |
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362 | firstFreeItem = -1; |
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363 | } |
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364 | |
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365 | /// \brief Finds the component of the given element. |
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366 | /// |
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367 | /// The method returns the component id of the given element. |
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368 | int find(const Item &item) const { |
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369 | return ~(items[repIndex(index[item])].parent); |
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370 | } |
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371 | |
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372 | /// \brief Joining the component of element \e a and element \e b. |
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373 | /// |
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374 | /// This is the \e union operation of the Union-Find structure. |
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375 | /// Joins the component of element \e a and component of |
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376 | /// element \e b. If \e a and \e b are in the same component then |
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377 | /// returns -1 else returns the remaining class. |
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378 | int join(const Item& a, const Item& b) { |
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379 | |
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380 | int ak = repIndex(index[a]); |
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381 | int bk = repIndex(index[b]); |
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382 | |
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383 | if (ak == bk) { |
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384 | return -1; |
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385 | } |
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386 | |
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387 | int acx = ~(items[ak].parent); |
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388 | int bcx = ~(items[bk].parent); |
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389 | |
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390 | int rcx; |
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391 | |
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392 | if (classes[acx].size > classes[bcx].size) { |
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393 | classes[acx].size += classes[bcx].size; |
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394 | items[bk].parent = ak; |
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395 | unlaceClass(bcx); |
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396 | rcx = acx; |
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397 | } else { |
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398 | classes[bcx].size += classes[acx].size; |
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399 | items[ak].parent = bk; |
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400 | unlaceClass(acx); |
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401 | rcx = bcx; |
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402 | } |
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403 | spliceItems(ak, bk); |
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404 | |
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405 | return rcx; |
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406 | } |
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407 | |
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408 | /// \brief Returns the size of the class. |
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409 | /// |
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410 | /// Returns the size of the class. |
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411 | int size(int cls) const { |
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412 | return classes[cls].size; |
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413 | } |
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414 | |
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415 | /// \brief Splits up the component. |
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416 | /// |
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417 | /// Splitting the component into singleton components (component |
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418 | /// of size one). |
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419 | void split(int cls) { |
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420 | int fdx = classes[cls].firstItem; |
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421 | int idx = items[fdx].next; |
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422 | while (idx != fdx) { |
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423 | int next = items[idx].next; |
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424 | |
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425 | singletonItem(idx); |
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426 | |
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427 | int cdx = newClass(); |
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428 | items[idx].parent = ~cdx; |
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429 | |
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430 | laceClass(cdx); |
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431 | classes[cdx].size = 1; |
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432 | classes[cdx].firstItem = idx; |
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433 | |
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434 | idx = next; |
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435 | } |
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436 | |
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437 | items[idx].prev = idx; |
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438 | items[idx].next = idx; |
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439 | |
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440 | classes[~(items[idx].parent)].size = 1; |
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441 | |
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442 | } |
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443 | |
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444 | /// \brief Removes the given element from the structure. |
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445 | /// |
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446 | /// Removes the element from its component and if the component becomes |
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447 | /// empty then removes that component from the component list. |
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448 | /// |
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449 | /// \warning It is an error to remove an element which is not in |
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450 | /// the structure. |
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451 | /// \warning This running time of this operation is proportional to the |
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452 | /// number of the items in this class. |
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453 | void erase(const Item& item) { |
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454 | int idx = index[item]; |
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455 | int fdx = items[idx].next; |
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456 | |
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457 | int cdx = classIndex(idx); |
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458 | if (idx == fdx) { |
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459 | unlaceClass(cdx); |
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460 | items[idx].next = firstFreeItem; |
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461 | firstFreeItem = idx; |
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462 | return; |
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463 | } else { |
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464 | classes[cdx].firstItem = fdx; |
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465 | --classes[cdx].size; |
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466 | items[fdx].parent = ~cdx; |
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467 | |
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468 | unlaceItem(idx); |
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469 | idx = items[fdx].next; |
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470 | while (idx != fdx) { |
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471 | items[idx].parent = fdx; |
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472 | idx = items[idx].next; |
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473 | } |
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474 | |
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475 | } |
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476 | |
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477 | } |
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478 | |
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479 | /// \brief Gives back a representant item of the component. |
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480 | /// |
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481 | /// Gives back a representant item of the component. |
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482 | Item item(int cls) const { |
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483 | return items[classes[cls].firstItem].item; |
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484 | } |
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485 | |
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486 | /// \brief Removes the component of the given element from the structure. |
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487 | /// |
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488 | /// Removes the component of the given element from the structure. |
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489 | /// |
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490 | /// \warning It is an error to give an element which is not in the |
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491 | /// structure. |
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492 | void eraseClass(int cls) { |
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493 | int fdx = classes[cls].firstItem; |
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494 | unlaceClass(cls); |
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495 | items[items[fdx].prev].next = firstFreeItem; |
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496 | firstFreeItem = fdx; |
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497 | } |
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498 | |
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499 | /// \brief Lemon style iterator for the representant items. |
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500 | /// |
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501 | /// ClassIt is a lemon style iterator for the components. It iterates |
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502 | /// on the ids of the classes. |
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503 | class ClassIt { |
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504 | public: |
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505 | /// \brief Constructor of the iterator |
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506 | /// |
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507 | /// Constructor of the iterator |
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508 | ClassIt(const UnionFindEnum& ufe) : unionFind(&ufe) { |
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509 | cdx = unionFind->firstClass; |
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510 | } |
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511 | |
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512 | /// \brief Constructor to get invalid iterator |
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513 | /// |
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514 | /// Constructor to get invalid iterator |
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515 | ClassIt(Invalid) : unionFind(0), cdx(-1) {} |
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516 | |
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517 | /// \brief Increment operator |
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518 | /// |
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519 | /// It steps to the next representant item. |
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520 | ClassIt& operator++() { |
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521 | cdx = unionFind->classes[cdx].next; |
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522 | return *this; |
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523 | } |
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524 | |
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525 | /// \brief Conversion operator |
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526 | /// |
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527 | /// It converts the iterator to the current representant item. |
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528 | operator int() const { |
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529 | return cdx; |
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530 | } |
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531 | |
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532 | /// \brief Equality operator |
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533 | /// |
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534 | /// Equality operator |
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535 | bool operator==(const ClassIt& i) { |
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536 | return i.cdx == cdx; |
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537 | } |
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538 | |
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539 | /// \brief Inequality operator |
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540 | /// |
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541 | /// Inequality operator |
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542 | bool operator!=(const ClassIt& i) { |
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543 | return i.cdx != cdx; |
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544 | } |
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545 | |
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546 | private: |
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547 | const UnionFindEnum* unionFind; |
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548 | int cdx; |
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549 | }; |
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550 | |
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551 | /// \brief Lemon style iterator for the items of a component. |
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552 | /// |
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553 | /// ClassIt is a lemon style iterator for the components. It iterates |
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554 | /// on the items of a class. By example if you want to iterate on |
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555 | /// each items of each classes then you may write the next code. |
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556 | ///\code |
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557 | /// for (ClassIt cit(ufe); cit != INVALID; ++cit) { |
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558 | /// std::cout << "Class: "; |
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559 | /// for (ItemIt iit(ufe, cit); iit != INVALID; ++iit) { |
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560 | /// std::cout << toString(iit) << ' ' << std::endl; |
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561 | /// } |
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562 | /// std::cout << std::endl; |
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563 | /// } |
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564 | ///\endcode |
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565 | class ItemIt { |
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566 | public: |
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567 | /// \brief Constructor of the iterator |
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568 | /// |
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569 | /// Constructor of the iterator. The iterator iterates |
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570 | /// on the class of the \c item. |
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571 | ItemIt(const UnionFindEnum& ufe, int cls) : unionFind(&ufe) { |
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572 | fdx = idx = unionFind->classes[cls].firstItem; |
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573 | } |
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574 | |
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575 | /// \brief Constructor to get invalid iterator |
---|
576 | /// |
---|
577 | /// Constructor to get invalid iterator |
---|
578 | ItemIt(Invalid) : unionFind(0), idx(-1) {} |
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579 | |
---|
580 | /// \brief Increment operator |
---|
581 | /// |
---|
582 | /// It steps to the next item in the class. |
---|
583 | ItemIt& operator++() { |
---|
584 | idx = unionFind->items[idx].next; |
---|
585 | if (idx == fdx) idx = -1; |
---|
586 | return *this; |
---|
587 | } |
---|
588 | |
---|
589 | /// \brief Conversion operator |
---|
590 | /// |
---|
591 | /// It converts the iterator to the current item. |
---|
592 | operator const Item&() const { |
---|
593 | return unionFind->items[idx].item; |
---|
594 | } |
---|
595 | |
---|
596 | /// \brief Equality operator |
---|
597 | /// |
---|
598 | /// Equality operator |
---|
599 | bool operator==(const ItemIt& i) { |
---|
600 | return i.idx == idx; |
---|
601 | } |
---|
602 | |
---|
603 | /// \brief Inequality operator |
---|
604 | /// |
---|
605 | /// Inequality operator |
---|
606 | bool operator!=(const ItemIt& i) { |
---|
607 | return i.idx != idx; |
---|
608 | } |
---|
609 | |
---|
610 | private: |
---|
611 | const UnionFindEnum* unionFind; |
---|
612 | int idx, fdx; |
---|
613 | }; |
---|
614 | |
---|
615 | }; |
---|
616 | |
---|
617 | /// \ingroup auxdat |
---|
618 | /// |
---|
619 | /// \brief A \e Extend-Find data structure implementation which |
---|
620 | /// is able to enumerate the components. |
---|
621 | /// |
---|
622 | /// The class implements an \e Extend-Find data structure which is |
---|
623 | /// able to enumerate the components and the items in a |
---|
624 | /// component. The data structure is a simplification of the |
---|
625 | /// Union-Find structure, and it does not allow to merge two components. |
---|
626 | /// |
---|
627 | /// \pre You need to add all the elements by the \ref insert() |
---|
628 | /// method. |
---|
629 | template <typename _ItemIntMap> |
---|
630 | class ExtendFindEnum { |
---|
631 | public: |
---|
632 | |
---|
633 | typedef _ItemIntMap ItemIntMap; |
---|
634 | typedef typename ItemIntMap::Key Item; |
---|
635 | |
---|
636 | private: |
---|
637 | |
---|
638 | ItemIntMap& index; |
---|
639 | |
---|
640 | struct ItemT { |
---|
641 | int cls; |
---|
642 | Item item; |
---|
643 | int next, prev; |
---|
644 | }; |
---|
645 | |
---|
646 | std::vector<ItemT> items; |
---|
647 | int firstFreeItem; |
---|
648 | |
---|
649 | struct ClassT { |
---|
650 | int firstItem; |
---|
651 | int next, prev; |
---|
652 | }; |
---|
653 | |
---|
654 | std::vector<ClassT> classes; |
---|
655 | |
---|
656 | int firstClass, firstFreeClass; |
---|
657 | |
---|
658 | int newClass() { |
---|
659 | if (firstFreeClass != -1) { |
---|
660 | int cdx = firstFreeClass; |
---|
661 | firstFreeClass = classes[cdx].next; |
---|
662 | return cdx; |
---|
663 | } else { |
---|
664 | classes.push_back(ClassT()); |
---|
665 | return classes.size() - 1; |
---|
666 | } |
---|
667 | } |
---|
668 | |
---|
669 | int newItem() { |
---|
670 | if (firstFreeItem != -1) { |
---|
671 | int idx = firstFreeItem; |
---|
672 | firstFreeItem = items[idx].next; |
---|
673 | return idx; |
---|
674 | } else { |
---|
675 | items.push_back(ItemT()); |
---|
676 | return items.size() - 1; |
---|
677 | } |
---|
678 | } |
---|
679 | |
---|
680 | public: |
---|
681 | |
---|
682 | /// \brief Constructor |
---|
683 | ExtendFindEnum(ItemIntMap& _index) |
---|
684 | : index(_index), items(), firstFreeItem(-1), |
---|
685 | classes(), firstClass(-1), firstFreeClass(-1) {} |
---|
686 | |
---|
687 | /// \brief Inserts the given element into a new component. |
---|
688 | /// |
---|
689 | /// This method creates a new component consisting only of the |
---|
690 | /// given element. |
---|
691 | int insert(const Item& item) { |
---|
692 | int cdx = newClass(); |
---|
693 | classes[cdx].prev = -1; |
---|
694 | classes[cdx].next = firstClass; |
---|
695 | if (firstClass != -1) { |
---|
696 | classes[firstClass].prev = cdx; |
---|
697 | } |
---|
698 | firstClass = cdx; |
---|
699 | |
---|
700 | int idx = newItem(); |
---|
701 | items[idx].item = item; |
---|
702 | items[idx].cls = cdx; |
---|
703 | items[idx].prev = idx; |
---|
704 | items[idx].next = idx; |
---|
705 | |
---|
706 | classes[cdx].firstItem = idx; |
---|
707 | |
---|
708 | index.set(item, idx); |
---|
709 | |
---|
710 | return cdx; |
---|
711 | } |
---|
712 | |
---|
713 | /// \brief Inserts the given element into the given component. |
---|
714 | /// |
---|
715 | /// This methods inserts the element \e item a into the \e cls class. |
---|
716 | void insert(const Item& item, int cls) { |
---|
717 | int idx = newItem(); |
---|
718 | int rdx = classes[cls].firstItem; |
---|
719 | items[idx].item = item; |
---|
720 | items[idx].cls = cls; |
---|
721 | |
---|
722 | items[idx].prev = rdx; |
---|
723 | items[idx].next = items[rdx].next; |
---|
724 | items[items[rdx].next].prev = idx; |
---|
725 | items[rdx].next = idx; |
---|
726 | |
---|
727 | index.set(item, idx); |
---|
728 | } |
---|
729 | |
---|
730 | /// \brief Clears the union-find data structure |
---|
731 | /// |
---|
732 | /// Erase each item from the data structure. |
---|
733 | void clear() { |
---|
734 | items.clear(); |
---|
735 | classes.clear; |
---|
736 | firstClass = firstFreeClass = firstFreeItem = -1; |
---|
737 | } |
---|
738 | |
---|
739 | /// \brief Gives back the class of the \e item. |
---|
740 | /// |
---|
741 | /// Gives back the class of the \e item. |
---|
742 | int find(const Item &item) const { |
---|
743 | return items[index[item]].cls; |
---|
744 | } |
---|
745 | |
---|
746 | /// \brief Gives back a representant item of the component. |
---|
747 | /// |
---|
748 | /// Gives back a representant item of the component. |
---|
749 | Item item(int cls) const { |
---|
750 | return items[classes[cls].firstItem].item; |
---|
751 | } |
---|
752 | |
---|
753 | /// \brief Removes the given element from the structure. |
---|
754 | /// |
---|
755 | /// Removes the element from its component and if the component becomes |
---|
756 | /// empty then removes that component from the component list. |
---|
757 | /// |
---|
758 | /// \warning It is an error to remove an element which is not in |
---|
759 | /// the structure. |
---|
760 | void erase(const Item &item) { |
---|
761 | int idx = index[item]; |
---|
762 | int cdx = items[idx].cls; |
---|
763 | |
---|
764 | if (idx == items[idx].next) { |
---|
765 | if (classes[cdx].prev != -1) { |
---|
766 | classes[classes[cdx].prev].next = classes[cdx].next; |
---|
767 | } else { |
---|
768 | firstClass = classes[cdx].next; |
---|
769 | } |
---|
770 | if (classes[cdx].next != -1) { |
---|
771 | classes[classes[cdx].next].prev = classes[cdx].prev; |
---|
772 | } |
---|
773 | classes[cdx].next = firstFreeClass; |
---|
774 | firstFreeClass = cdx; |
---|
775 | } else { |
---|
776 | classes[cdx].firstItem = items[idx].next; |
---|
777 | items[items[idx].next].prev = items[idx].prev; |
---|
778 | items[items[idx].prev].next = items[idx].next; |
---|
779 | } |
---|
780 | items[idx].next = firstFreeItem; |
---|
781 | firstFreeItem = idx; |
---|
782 | |
---|
783 | } |
---|
784 | |
---|
785 | |
---|
786 | /// \brief Removes the component of the given element from the structure. |
---|
787 | /// |
---|
788 | /// Removes the component of the given element from the structure. |
---|
789 | /// |
---|
790 | /// \warning It is an error to give an element which is not in the |
---|
791 | /// structure. |
---|
792 | void eraseClass(int cdx) { |
---|
793 | int idx = classes[cdx].firstItem; |
---|
794 | items[items[idx].prev].next = firstFreeItem; |
---|
795 | firstFreeItem = idx; |
---|
796 | |
---|
797 | if (classes[cdx].prev != -1) { |
---|
798 | classes[classes[cdx].prev].next = classes[cdx].next; |
---|
799 | } else { |
---|
800 | firstClass = classes[cdx].next; |
---|
801 | } |
---|
802 | if (classes[cdx].next != -1) { |
---|
803 | classes[classes[cdx].next].prev = classes[cdx].prev; |
---|
804 | } |
---|
805 | classes[cdx].next = firstFreeClass; |
---|
806 | firstFreeClass = cdx; |
---|
807 | } |
---|
808 | |
---|
809 | /// \brief Lemon style iterator for the classes. |
---|
810 | /// |
---|
811 | /// ClassIt is a lemon style iterator for the components. It iterates |
---|
812 | /// on the ids of classes. |
---|
813 | class ClassIt { |
---|
814 | public: |
---|
815 | /// \brief Constructor of the iterator |
---|
816 | /// |
---|
817 | /// Constructor of the iterator |
---|
818 | ClassIt(const ExtendFindEnum& ufe) : extendFind(&ufe) { |
---|
819 | cdx = extendFind->firstClass; |
---|
820 | } |
---|
821 | |
---|
822 | /// \brief Constructor to get invalid iterator |
---|
823 | /// |
---|
824 | /// Constructor to get invalid iterator |
---|
825 | ClassIt(Invalid) : extendFind(0), cdx(-1) {} |
---|
826 | |
---|
827 | /// \brief Increment operator |
---|
828 | /// |
---|
829 | /// It steps to the next representant item. |
---|
830 | ClassIt& operator++() { |
---|
831 | cdx = extendFind->classes[cdx].next; |
---|
832 | return *this; |
---|
833 | } |
---|
834 | |
---|
835 | /// \brief Conversion operator |
---|
836 | /// |
---|
837 | /// It converts the iterator to the current class id. |
---|
838 | operator int() const { |
---|
839 | return cdx; |
---|
840 | } |
---|
841 | |
---|
842 | /// \brief Equality operator |
---|
843 | /// |
---|
844 | /// Equality operator |
---|
845 | bool operator==(const ClassIt& i) { |
---|
846 | return i.cdx == cdx; |
---|
847 | } |
---|
848 | |
---|
849 | /// \brief Inequality operator |
---|
850 | /// |
---|
851 | /// Inequality operator |
---|
852 | bool operator!=(const ClassIt& i) { |
---|
853 | return i.cdx != cdx; |
---|
854 | } |
---|
855 | |
---|
856 | private: |
---|
857 | const ExtendFindEnum* extendFind; |
---|
858 | int cdx; |
---|
859 | }; |
---|
860 | |
---|
861 | /// \brief Lemon style iterator for the items of a component. |
---|
862 | /// |
---|
863 | /// ClassIt is a lemon style iterator for the components. It iterates |
---|
864 | /// on the items of a class. By example if you want to iterate on |
---|
865 | /// each items of each classes then you may write the next code. |
---|
866 | ///\code |
---|
867 | /// for (ClassIt cit(ufe); cit != INVALID; ++cit) { |
---|
868 | /// std::cout << "Class: "; |
---|
869 | /// for (ItemIt iit(ufe, cit); iit != INVALID; ++iit) { |
---|
870 | /// std::cout << toString(iit) << ' ' << std::endl; |
---|
871 | /// } |
---|
872 | /// std::cout << std::endl; |
---|
873 | /// } |
---|
874 | ///\endcode |
---|
875 | class ItemIt { |
---|
876 | public: |
---|
877 | /// \brief Constructor of the iterator |
---|
878 | /// |
---|
879 | /// Constructor of the iterator. The iterator iterates |
---|
880 | /// on the class of the \c item. |
---|
881 | ItemIt(const ExtendFindEnum& ufe, int cls) : extendFind(&ufe) { |
---|
882 | fdx = idx = extendFind->classes[cls].firstItem; |
---|
883 | } |
---|
884 | |
---|
885 | /// \brief Constructor to get invalid iterator |
---|
886 | /// |
---|
887 | /// Constructor to get invalid iterator |
---|
888 | ItemIt(Invalid) : extendFind(0), idx(-1) {} |
---|
889 | |
---|
890 | /// \brief Increment operator |
---|
891 | /// |
---|
892 | /// It steps to the next item in the class. |
---|
893 | ItemIt& operator++() { |
---|
894 | idx = extendFind->items[idx].next; |
---|
895 | if (fdx == idx) idx = -1; |
---|
896 | return *this; |
---|
897 | } |
---|
898 | |
---|
899 | /// \brief Conversion operator |
---|
900 | /// |
---|
901 | /// It converts the iterator to the current item. |
---|
902 | operator const Item&() const { |
---|
903 | return extendFind->items[idx].item; |
---|
904 | } |
---|
905 | |
---|
906 | /// \brief Equality operator |
---|
907 | /// |
---|
908 | /// Equality operator |
---|
909 | bool operator==(const ItemIt& i) { |
---|
910 | return i.idx == idx; |
---|
911 | } |
---|
912 | |
---|
913 | /// \brief Inequality operator |
---|
914 | /// |
---|
915 | /// Inequality operator |
---|
916 | bool operator!=(const ItemIt& i) { |
---|
917 | return i.idx != idx; |
---|
918 | } |
---|
919 | |
---|
920 | private: |
---|
921 | const ExtendFindEnum* extendFind; |
---|
922 | int idx, fdx; |
---|
923 | }; |
---|
924 | |
---|
925 | }; |
---|
926 | |
---|
927 | //! @} |
---|
928 | |
---|
929 | } //namespace lemon |
---|
930 | |
---|
931 | #endif //LEMON_UNION_FIND_H |
---|