1 | /* -*- C++ -*- |
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2 | * src/lemon/bin_heap.h - Part of LEMON, a generic C++ optimization library |
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3 | * |
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4 | * Copyright (C) 2005 Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport |
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5 | * (Egervary Combinatorial Optimization Research Group, EGRES). |
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6 | * |
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7 | * Permission to use, modify and distribute this software is granted |
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8 | * provided that this copyright notice appears in all copies. For |
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9 | * precise terms see the accompanying LICENSE file. |
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10 | * |
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11 | * This software is provided "AS IS" with no warranty of any kind, |
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12 | * express or implied, and with no claim as to its suitability for any |
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13 | * purpose. |
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14 | * |
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15 | */ |
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16 | |
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17 | #ifndef LEMON_RADIX_HEAP_H |
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18 | #define LEMON_RADIX_HEAP_H |
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19 | |
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20 | ///\ingroup auxdat |
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21 | ///\file |
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22 | ///\brief Radix Heap implementation. |
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23 | ///\todo It should be documented. |
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24 | |
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25 | #include <vector> |
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26 | #include <lemon/error.h> |
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27 | |
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28 | namespace lemon { |
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29 | |
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30 | /// \addtogroup auxdat |
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31 | /// @{ |
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32 | |
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33 | /// A Binary Heap implementation. |
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34 | |
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35 | ///\todo Please document... |
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36 | /// |
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37 | ///\sa BinHeap |
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38 | ///\sa Dijkstra |
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39 | |
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40 | class UnderFlowPriorityException : public RuntimeError { |
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41 | public: |
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42 | virtual const char* exceptionName() const { |
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43 | return "lemon::UnderFlowPriorityException"; |
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44 | } |
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45 | }; |
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46 | |
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47 | template <typename _Item, typename _ItemIntMap> |
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48 | class RadixHeap { |
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49 | |
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50 | public: |
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51 | typedef _Item Item; |
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52 | // FIXME: stl-ben nem ezt hivjak value_type -nak, hanem a kovetkezot... |
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53 | typedef int Prio; |
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54 | typedef _ItemIntMap ItemIntMap; |
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55 | |
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56 | /** |
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57 | * Each Item element have a state associated to it. It may be "in heap", |
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58 | * "pre heap" or "post heap". The later two are indifferent from the |
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59 | * heap's point of view, but may be useful to the user. |
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60 | * |
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61 | * The ItemIntMap _should_ be initialized in such way, that it maps |
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62 | * PRE_HEAP (-1) to any element to be put in the heap... |
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63 | */ |
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64 | ///\todo it is used nowhere |
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65 | /// |
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66 | enum state_enum { |
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67 | IN_HEAP = 0, |
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68 | PRE_HEAP = -1, |
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69 | POST_HEAP = -2 |
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70 | }; |
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71 | |
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72 | private: |
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73 | |
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74 | struct RadixItem { |
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75 | int prev, next, box; |
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76 | Item item; |
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77 | int prio; |
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78 | RadixItem(Item _item, int _prio) : item(_item), prio(_prio) {} |
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79 | }; |
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80 | |
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81 | struct RadixBox { |
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82 | int first; |
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83 | int min, size; |
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84 | RadixBox(int _min, int _size) : first(-1), min(_min), size(_size) {} |
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85 | }; |
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86 | |
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87 | std::vector<RadixItem> data; |
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88 | std::vector<RadixBox> boxes; |
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89 | |
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90 | ItemIntMap &iim; |
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91 | |
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92 | |
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93 | public: |
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94 | ///\e |
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95 | explicit RadixHeap(ItemIntMap &_iim) : iim(_iim) { |
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96 | boxes.push_back(RadixBox(0, 1)); |
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97 | boxes.push_back(RadixBox(1, 1)); |
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98 | } |
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99 | |
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100 | ///\e |
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101 | RadixHeap(ItemIntMap &_iim, int capacity) : iim(_iim) { |
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102 | boxes.push_back(RadixBox(0, 1)); |
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103 | boxes.push_back(RadixBox(1, 1)); |
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104 | while (upper(boxes.back(), capacity)) { |
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105 | extend(); |
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106 | } |
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107 | } |
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108 | |
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109 | ///\e |
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110 | int size() const { return data.size(); } |
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111 | ///\e |
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112 | bool empty() const { return data.empty(); } |
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113 | |
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114 | private: |
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115 | |
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116 | bool upper(int box, Prio prio) { |
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117 | return prio < boxes[box].min; |
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118 | } |
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119 | |
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120 | bool lower(int box, Prio prio) { |
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121 | return prio >= boxes[box].min + boxes[box].size; |
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122 | } |
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123 | |
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124 | /// \brief Remove item from the box list. |
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125 | void remove(int index) { |
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126 | if (data[index].prev >= 0) { |
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127 | data[data[index].prev].next = data[index].next; |
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128 | } else { |
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129 | boxes[data[index].box].first = data[index].next; |
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130 | } |
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131 | if (data[index].next >= 0) { |
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132 | data[data[index].next].prev = data[index].prev; |
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133 | } |
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134 | } |
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135 | |
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136 | /// \brief Insert item into the box list. |
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137 | void insert(int box, int index) { |
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138 | if (boxes[box].first == -1) { |
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139 | boxes[box].first = index; |
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140 | data[index].next = data[index].prev = -1; |
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141 | } else { |
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142 | data[index].next = boxes[box].first; |
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143 | data[boxes[box].first].prev = index; |
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144 | data[index].prev = -1; |
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145 | boxes[box].first = index; |
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146 | } |
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147 | data[index].box = box; |
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148 | } |
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149 | |
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150 | /// \brief Add a new box to the box list. |
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151 | void extend() { |
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152 | int min = boxes.back().min + boxes.back().size; |
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153 | int size = 2 * boxes.back().size; |
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154 | boxes.push_back(RadixBox(min, size)); |
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155 | } |
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156 | |
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157 | /// \brief Move an item up into the proper box. |
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158 | void bubble_up(int index) { |
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159 | if (!lower(data[index].box, index)) return; |
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160 | remove(index); |
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161 | int box = findUp(data[index].box, data[index].prio); |
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162 | insert(box, index); |
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163 | } |
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164 | |
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165 | /// \brief Find up the proper box for the item with the given prio. |
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166 | int findUp(int start, int prio) { |
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167 | while (lower(start, prio)) { |
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168 | if (++start == (int)boxes.size()) { |
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169 | extend(); |
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170 | } |
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171 | } |
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172 | return start; |
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173 | } |
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174 | |
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175 | /// \brief Move an item down into the proper box. |
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176 | void bubble_down(int index) { |
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177 | if (!upper(data[index].box, data[index].prio)) return; |
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178 | remove(index); |
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179 | int box = findDown(data[index].box, data[index].prio); |
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180 | insert(box, index); |
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181 | } |
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182 | |
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183 | /// \brief Find up the proper box for the item with the given prio. |
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184 | int findDown(int start, int prio) { |
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185 | while (upper(start, prio)) { |
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186 | if (--start < 0) throw UnderFlowPriorityException(); |
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187 | } |
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188 | return start; |
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189 | } |
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190 | |
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191 | /// \brief Find the first not empty box. |
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192 | int findFirst() { |
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193 | int first = 0; |
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194 | while (boxes[first].first == -1) ++first; |
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195 | return first; |
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196 | } |
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197 | |
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198 | /// \brief Gives back the minimal prio of the box. |
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199 | int minValue(int box) { |
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200 | int min = data[boxes[box].first].prio; |
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201 | for (int k = boxes[box].first; k != -1; k = data[k].next) { |
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202 | if (data[k].prio < min) min = data[k].prio; |
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203 | } |
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204 | return min; |
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205 | } |
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206 | |
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207 | /// \brief Rearrange the items of the heap and makes the |
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208 | /// first box not empty. |
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209 | void moveDown() { |
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210 | // print(); printf("moveDown\n"); fflush(stdout); |
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211 | int box = findFirst(); |
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212 | if (box == 0) return; |
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213 | int min = minValue(box); |
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214 | for (int i = 0; i <= box; ++i) { |
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215 | boxes[i].min = min; |
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216 | min += boxes[i].size; |
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217 | } |
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218 | int curr = boxes[box].first, next; |
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219 | while (curr != -1) { |
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220 | next = data[curr].next; |
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221 | bubble_down(curr); |
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222 | curr = next; |
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223 | } |
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224 | } |
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225 | |
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226 | void relocate_last(int index) { |
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227 | if (index != (int)data.size() - 1) { |
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228 | data[index] = data.back(); |
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229 | if (data[index].prev != -1) { |
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230 | data[data[index].prev].next = index; |
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231 | } else { |
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232 | boxes[data[index].box].first = index; |
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233 | } |
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234 | if (data[index].next != -1) { |
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235 | data[data[index].next].prev = index; |
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236 | } |
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237 | iim[data[index].item] = index; |
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238 | } |
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239 | data.pop_back(); |
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240 | } |
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241 | |
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242 | public: |
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243 | |
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244 | ///\e |
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245 | void push(const Item &i, const Prio &p) { |
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246 | fflush(stdout); |
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247 | int n = data.size(); |
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248 | iim.set(i, n); |
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249 | data.push_back(RadixItem(i, p)); |
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250 | while (lower(boxes.size() - 1, p)) { |
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251 | extend(); |
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252 | } |
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253 | int box = findDown(boxes.size() - 1, p); |
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254 | insert(box, n); |
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255 | // printf("Push %d\n", p); |
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256 | //print(); |
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257 | } |
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258 | |
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259 | ///\e |
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260 | Item top() const { |
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261 | // print(); printf("top\n"); fflush(stdout); |
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262 | const_cast<RadixHeap<Item, ItemIntMap>*>(this)->moveDown(); |
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263 | return data[boxes[0].first].item; |
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264 | // print(); printf("top_end\n"); fflush(stdout); |
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265 | } |
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266 | |
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267 | /// Returns the prio of the top element of the heap. |
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268 | Prio prio() const { |
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269 | // print(); printf("prio\n"); fflush(stdout); |
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270 | const_cast<RadixHeap<Item, ItemIntMap>*>(this)->moveDown(); |
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271 | return data[boxes[0].first].prio; |
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272 | } |
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273 | |
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274 | ///\e |
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275 | void pop() { |
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276 | // print(); printf("pop\n"); fflush(stdout); |
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277 | moveDown(); |
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278 | int index = boxes[0].first; |
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279 | iim[data[index].item] = POST_HEAP; |
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280 | remove(index); |
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281 | relocate_last(index); |
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282 | // printf("Pop \n"); |
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283 | //print(); |
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284 | } |
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285 | |
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286 | ///\e |
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287 | void erase(const Item &i) { |
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288 | int index = iim[i]; |
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289 | iim[i] = POST_HEAP; |
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290 | remove(index); |
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291 | relocate_last(index); |
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292 | } |
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293 | |
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294 | ///\e |
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295 | Prio operator[](const Item &i) const { |
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296 | int idx = iim[i]; |
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297 | return data[idx].prio; |
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298 | } |
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299 | |
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300 | ///\e |
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301 | void set(const Item &i, const Prio &p) { |
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302 | int idx = iim[i]; |
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303 | if( idx < 0 ) { |
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304 | push(i, p); |
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305 | } |
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306 | else if( p >= data[idx].prio ) { |
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307 | data[idx].prio = p; |
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308 | bubble_up(idx); |
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309 | } else { |
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310 | data[idx].prio = p; |
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311 | bubble_down(idx); |
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312 | } |
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313 | } |
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314 | |
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315 | ///\e |
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316 | void decrease(const Item &i, const Prio &p) { |
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317 | // print(); printf("decrease\n"); fflush(stdout); |
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318 | int idx = iim[i]; |
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319 | data[idx].prio = p; |
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320 | bubble_down(idx); |
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321 | } |
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322 | |
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323 | ///\e |
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324 | void increase(const Item &i, const Prio &p) { |
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325 | int idx = iim[i]; |
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326 | data[idx].prio = p; |
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327 | bubble_up(idx); |
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328 | } |
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329 | |
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330 | ///\e |
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331 | state_enum state(const Item &i) const { |
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332 | int s = iim[i]; |
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333 | if( s >= 0 ) s = 0; |
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334 | return state_enum(s); |
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335 | } |
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336 | |
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337 | void print() const { |
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338 | for (int i = 0; i < boxes.size(); ++i) { |
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339 | printf("(%d, %d) ", boxes[i].min, boxes[i].size); |
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340 | for (int k = boxes[i].first; k != -1; k = data[k].next) { |
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341 | printf("%d ", data[k].prio); |
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342 | } |
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343 | printf("\n"); |
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344 | } |
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345 | fflush(stdout); |
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346 | } |
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347 | |
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348 | }; // class RadixHeap |
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349 | |
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350 | |
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351 | ///@} |
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352 | |
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353 | } // namespace lemon |
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354 | |
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355 | #endif // LEMON_RADIX_HEAP_H |
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