1 | /* -*- mode: C++; indent-tabs-mode: nil; -*- |
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2 | * |
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3 | * This file is a part of LEMON, a generic C++ optimization library. |
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4 | * |
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5 | * Copyright (C) 2003-2009 |
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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_CONCEPTS_HEAP_H |
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20 | #define LEMON_CONCEPTS_HEAP_H |
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21 | |
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22 | ///\ingroup concept |
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23 | ///\file |
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24 | ///\brief The concept of heaps. |
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25 | |
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26 | #include <lemon/core.h> |
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27 | #include <lemon/concept_check.h> |
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28 | |
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29 | namespace lemon { |
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30 | |
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31 | namespace concepts { |
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32 | |
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33 | /// \addtogroup concept |
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34 | /// @{ |
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35 | |
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36 | /// \brief The heap concept. |
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37 | /// |
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38 | /// This concept class describes the main interface of heaps. |
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39 | /// The various heap structures are efficient |
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40 | /// implementations of the abstract data type \e priority \e queue. |
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41 | /// They store items with specified values called \e priorities |
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42 | /// in such a way that finding and removing the item with minimum |
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43 | /// priority are efficient. The basic operations are adding and |
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44 | /// erasing items, changing the priority of an item, etc. |
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45 | /// |
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46 | /// Heaps are crucial in several algorithms, such as Dijkstra and Prim. |
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47 | /// Any class that conforms to this concept can be used easily in such |
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48 | /// algorithms. |
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49 | /// |
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50 | /// \tparam PR Type of the priorities of the items. |
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51 | /// \tparam IM A read-writable item map with \c int values, used |
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52 | /// internally to handle the cross references. |
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53 | /// \tparam CMP A functor class for comparing the priorities. |
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54 | /// The default is \c std::less<PR>. |
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55 | #ifdef DOXYGEN |
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56 | template <typename PR, typename IM, typename CMP> |
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57 | #else |
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58 | template <typename PR, typename IM, typename CMP = std::less<PR> > |
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59 | #endif |
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60 | class Heap { |
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61 | public: |
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62 | |
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63 | /// Type of the item-int map. |
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64 | typedef IM ItemIntMap; |
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65 | /// Type of the priorities. |
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66 | typedef PR Prio; |
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67 | /// Type of the items stored in the heap. |
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68 | typedef typename ItemIntMap::Key Item; |
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69 | |
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70 | /// \brief Type to represent the states of the items. |
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71 | /// |
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72 | /// Each item has a state associated to it. It can be "in heap", |
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73 | /// "pre-heap" or "post-heap". The latter two are indifferent from the |
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74 | /// heap's point of view, but may be useful to the user. |
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75 | /// |
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76 | /// The item-int map must be initialized in such way that it assigns |
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77 | /// \c PRE_HEAP (<tt>-1</tt>) to any element to be put in the heap. |
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78 | enum State { |
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79 | IN_HEAP = 0, ///< = 0. The "in heap" state constant. |
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80 | PRE_HEAP = -1, ///< = -1. The "pre-heap" state constant. |
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81 | POST_HEAP = -2 ///< = -2. The "post-heap" state constant. |
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82 | }; |
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83 | |
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84 | /// \brief Constructor. |
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85 | /// |
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86 | /// Constructor. |
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87 | /// \param map A map that assigns \c int values to keys of type |
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88 | /// \c Item. It is used internally by the heap implementations to |
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89 | /// handle the cross references. The assigned value must be |
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90 | /// \c PRE_HEAP (<tt>-1</tt>) for each item. |
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91 | explicit Heap(ItemIntMap &map) {} |
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92 | |
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93 | /// \brief Constructor. |
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94 | /// |
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95 | /// Constructor. |
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96 | /// \param map A map that assigns \c int values to keys of type |
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97 | /// \c Item. It is used internally by the heap implementations to |
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98 | /// handle the cross references. The assigned value must be |
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99 | /// \c PRE_HEAP (<tt>-1</tt>) for each item. |
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100 | /// \param comp The function object used for comparing the priorities. |
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101 | explicit Heap(ItemIntMap &map, const CMP &comp) {} |
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102 | |
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103 | /// \brief The number of items stored in the heap. |
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104 | /// |
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105 | /// This function returns the number of items stored in the heap. |
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106 | int size() const { return 0; } |
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107 | |
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108 | /// \brief Check if the heap is empty. |
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109 | /// |
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110 | /// This function returns \c true if the heap is empty. |
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111 | bool empty() const { return false; } |
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112 | |
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113 | /// \brief Make the heap empty. |
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114 | /// |
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115 | /// This functon makes the heap empty. |
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116 | /// It does not change the cross reference map. If you want to reuse |
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117 | /// a heap that is not surely empty, you should first clear it and |
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118 | /// then you should set the cross reference map to \c PRE_HEAP |
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119 | /// for each item. |
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120 | void clear() {} |
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121 | |
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122 | /// \brief Insert an item into the heap with the given priority. |
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123 | /// |
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124 | /// This function inserts the given item into the heap with the |
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125 | /// given priority. |
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126 | /// \param i The item to insert. |
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127 | /// \param p The priority of the item. |
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128 | /// \pre \e i must not be stored in the heap. |
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129 | void push(const Item &i, const Prio &p) {} |
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130 | |
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131 | /// \brief Return the item having minimum priority. |
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132 | /// |
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133 | /// This function returns the item having minimum priority. |
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134 | /// \pre The heap must be non-empty. |
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135 | Item top() const {} |
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136 | |
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137 | /// \brief The minimum priority. |
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138 | /// |
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139 | /// This function returns the minimum priority. |
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140 | /// \pre The heap must be non-empty. |
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141 | Prio prio() const {} |
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142 | |
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143 | /// \brief Remove the item having minimum priority. |
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144 | /// |
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145 | /// This function removes the item having minimum priority. |
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146 | /// \pre The heap must be non-empty. |
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147 | void pop() {} |
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148 | |
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149 | /// \brief Remove the given item from the heap. |
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150 | /// |
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151 | /// This function removes the given item from the heap if it is |
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152 | /// already stored. |
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153 | /// \param i The item to delete. |
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154 | /// \pre \e i must be in the heap. |
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155 | void erase(const Item &i) {} |
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156 | |
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157 | /// \brief The priority of the given item. |
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158 | /// |
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159 | /// This function returns the priority of the given item. |
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160 | /// \param i The item. |
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161 | /// \pre \e i must be in the heap. |
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162 | Prio operator[](const Item &i) const {} |
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163 | |
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164 | /// \brief Set the priority of an item or insert it, if it is |
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165 | /// not stored in the heap. |
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166 | /// |
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167 | /// This method sets the priority of the given item if it is |
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168 | /// already stored in the heap. Otherwise it inserts the given |
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169 | /// item into the heap with the given priority. |
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170 | /// |
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171 | /// \param i The item. |
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172 | /// \param p The priority. |
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173 | void set(const Item &i, const Prio &p) {} |
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174 | |
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175 | /// \brief Decrease the priority of an item to the given value. |
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176 | /// |
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177 | /// This function decreases the priority of an item to the given value. |
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178 | /// \param i The item. |
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179 | /// \param p The priority. |
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180 | /// \pre \e i must be stored in the heap with priority at least \e p. |
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181 | void decrease(const Item &i, const Prio &p) {} |
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182 | |
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183 | /// \brief Increase the priority of an item to the given value. |
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184 | /// |
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185 | /// This function increases the priority of an item to the given value. |
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186 | /// \param i The item. |
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187 | /// \param p The priority. |
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188 | /// \pre \e i must be stored in the heap with priority at most \e p. |
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189 | void increase(const Item &i, const Prio &p) {} |
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190 | |
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191 | /// \brief Return the state of an item. |
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192 | /// |
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193 | /// This method returns \c PRE_HEAP if the given item has never |
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194 | /// been in the heap, \c IN_HEAP if it is in the heap at the moment, |
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195 | /// and \c POST_HEAP otherwise. |
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196 | /// In the latter case it is possible that the item will get back |
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197 | /// to the heap again. |
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198 | /// \param i The item. |
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199 | State state(const Item &i) const {} |
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200 | |
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201 | /// \brief Set the state of an item in the heap. |
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202 | /// |
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203 | /// This function sets the state of the given item in the heap. |
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204 | /// It can be used to manually clear the heap when it is important |
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205 | /// to achive better time complexity. |
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206 | /// \param i The item. |
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207 | /// \param st The state. It should not be \c IN_HEAP. |
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208 | void state(const Item& i, State st) {} |
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209 | |
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210 | |
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211 | template <typename _Heap> |
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212 | struct Constraints { |
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213 | public: |
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214 | void constraints() { |
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215 | typedef typename _Heap::Item OwnItem; |
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216 | typedef typename _Heap::Prio OwnPrio; |
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217 | typedef typename _Heap::State OwnState; |
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218 | |
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219 | Item item; |
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220 | Prio prio; |
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221 | item=Item(); |
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222 | prio=Prio(); |
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223 | ignore_unused_variable_warning(item); |
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224 | ignore_unused_variable_warning(prio); |
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225 | |
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226 | OwnItem own_item; |
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227 | OwnPrio own_prio; |
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228 | OwnState own_state; |
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229 | own_item=Item(); |
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230 | own_prio=Prio(); |
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231 | ignore_unused_variable_warning(own_item); |
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232 | ignore_unused_variable_warning(own_prio); |
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233 | ignore_unused_variable_warning(own_state); |
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234 | |
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235 | _Heap heap1(map); |
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236 | _Heap heap2 = heap1; |
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237 | ignore_unused_variable_warning(heap1); |
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238 | ignore_unused_variable_warning(heap2); |
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239 | |
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240 | int s = heap.size(); |
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241 | ignore_unused_variable_warning(s); |
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242 | bool e = heap.empty(); |
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243 | ignore_unused_variable_warning(e); |
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244 | |
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245 | prio = heap.prio(); |
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246 | item = heap.top(); |
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247 | prio = heap[item]; |
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248 | own_prio = heap.prio(); |
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249 | own_item = heap.top(); |
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250 | own_prio = heap[own_item]; |
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251 | |
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252 | heap.push(item, prio); |
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253 | heap.push(own_item, own_prio); |
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254 | heap.pop(); |
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255 | |
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256 | heap.set(item, prio); |
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257 | heap.decrease(item, prio); |
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258 | heap.increase(item, prio); |
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259 | heap.set(own_item, own_prio); |
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260 | heap.decrease(own_item, own_prio); |
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261 | heap.increase(own_item, own_prio); |
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262 | |
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263 | heap.erase(item); |
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264 | heap.erase(own_item); |
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265 | heap.clear(); |
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266 | |
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267 | own_state = heap.state(own_item); |
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268 | heap.state(own_item, own_state); |
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269 | |
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270 | own_state = _Heap::PRE_HEAP; |
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271 | own_state = _Heap::IN_HEAP; |
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272 | own_state = _Heap::POST_HEAP; |
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273 | } |
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274 | |
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275 | _Heap& heap; |
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276 | ItemIntMap& map; |
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277 | }; |
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278 | }; |
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279 | |
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280 | /// @} |
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281 | } // namespace lemon |
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282 | } |
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283 | #endif |
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