[728] | 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_BUCKET_HEAP_H |
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| 20 | #define LEMON_BUCKET_HEAP_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 Bucket Heap implementation. |
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| 25 | |
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| 26 | #include <vector> |
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| 27 | #include <utility> |
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| 28 | #include <functional> |
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| 29 | |
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| 30 | namespace lemon { |
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| 31 | |
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[729] | 32 | namespace _bucket_heap_bits { |
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| 33 | |
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[730] | 34 | template <bool MIN> |
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[729] | 35 | struct DirectionTraits { |
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| 36 | static bool less(int left, int right) { |
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| 37 | return left < right; |
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| 38 | } |
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| 39 | static void increase(int& value) { |
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| 40 | ++value; |
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| 41 | } |
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| 42 | }; |
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| 43 | |
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| 44 | template <> |
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| 45 | struct DirectionTraits<false> { |
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| 46 | static bool less(int left, int right) { |
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| 47 | return left > right; |
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| 48 | } |
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| 49 | static void increase(int& value) { |
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| 50 | --value; |
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| 51 | } |
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| 52 | }; |
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| 53 | |
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| 54 | } |
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| 55 | |
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[728] | 56 | /// \ingroup auxdat |
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| 57 | /// |
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| 58 | /// \brief A Bucket Heap implementation. |
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| 59 | /// |
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| 60 | /// This class implements the \e bucket \e heap data structure. A \e heap |
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| 61 | /// is a data structure for storing items with specified values called \e |
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| 62 | /// priorities in such a way that finding the item with minimum priority is |
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| 63 | /// efficient. The bucket heap is very simple implementation, it can store |
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| 64 | /// only integer priorities and it stores for each priority in the |
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| 65 | /// \f$ [0..C) \f$ range a list of items. So it should be used only when |
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| 66 | /// the priorities are small. It is not intended to use as dijkstra heap. |
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| 67 | /// |
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[730] | 68 | /// \param IM A read and write Item int map, used internally |
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[728] | 69 | /// to handle the cross references. |
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[730] | 70 | /// \param MIN If the given parameter is false then instead of the |
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| 71 | /// minimum value the maximum can be retrivied with the top() and |
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| 72 | /// prio() member functions. |
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| 73 | template <typename IM, bool MIN = true> |
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[728] | 74 | class BucketHeap { |
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| 75 | |
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| 76 | public: |
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| 77 | /// \e |
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[730] | 78 | typedef typename IM::Key Item; |
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[728] | 79 | /// \e |
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| 80 | typedef int Prio; |
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| 81 | /// \e |
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| 82 | typedef std::pair<Item, Prio> Pair; |
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| 83 | /// \e |
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[730] | 84 | typedef IM ItemIntMap; |
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[728] | 85 | |
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[729] | 86 | private: |
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| 87 | |
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[730] | 88 | typedef _bucket_heap_bits::DirectionTraits<MIN> Direction; |
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[729] | 89 | |
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| 90 | public: |
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| 91 | |
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[728] | 92 | /// \brief Type to represent the items states. |
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| 93 | /// |
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| 94 | /// Each Item element have a state associated to it. It may be "in heap", |
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| 95 | /// "pre heap" or "post heap". The latter two are indifferent from the |
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| 96 | /// heap's point of view, but may be useful to the user. |
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| 97 | /// |
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[730] | 98 | /// The item-int map must be initialized in such way that it assigns |
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| 99 | /// \c PRE_HEAP (<tt>-1</tt>) to any element to be put in the heap. |
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[728] | 100 | enum State { |
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[730] | 101 | IN_HEAP = 0, ///< = 0. |
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| 102 | PRE_HEAP = -1, ///< = -1. |
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| 103 | POST_HEAP = -2 ///< = -2. |
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[728] | 104 | }; |
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| 105 | |
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| 106 | public: |
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| 107 | /// \brief The constructor. |
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| 108 | /// |
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| 109 | /// The constructor. |
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[730] | 110 | /// \param map should be given to the constructor, since it is used |
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[728] | 111 | /// internally to handle the cross references. The value of the map |
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| 112 | /// should be PRE_HEAP (-1) for each element. |
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[730] | 113 | explicit BucketHeap(ItemIntMap &map) : _iim(map), _minimum(0) {} |
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[728] | 114 | |
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| 115 | /// The number of items stored in the heap. |
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| 116 | /// |
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| 117 | /// \brief Returns the number of items stored in the heap. |
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[730] | 118 | int size() const { return _data.size(); } |
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[728] | 119 | |
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| 120 | /// \brief Checks if the heap stores no items. |
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| 121 | /// |
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| 122 | /// Returns \c true if and only if the heap stores no items. |
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[730] | 123 | bool empty() const { return _data.empty(); } |
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[728] | 124 | |
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| 125 | /// \brief Make empty this heap. |
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| 126 | /// |
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| 127 | /// Make empty this heap. It does not change the cross reference |
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| 128 | /// map. If you want to reuse a heap what is not surely empty you |
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| 129 | /// should first clear the heap and after that you should set the |
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| 130 | /// cross reference map for each item to \c PRE_HEAP. |
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| 131 | void clear() { |
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[730] | 132 | _data.clear(); _first.clear(); _minimum = 0; |
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[728] | 133 | } |
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| 134 | |
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| 135 | private: |
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| 136 | |
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| 137 | void relocate_last(int idx) { |
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[730] | 138 | if (idx + 1 < int(_data.size())) { |
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| 139 | _data[idx] = _data.back(); |
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| 140 | if (_data[idx].prev != -1) { |
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| 141 | _data[_data[idx].prev].next = idx; |
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[728] | 142 | } else { |
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[730] | 143 | _first[_data[idx].value] = idx; |
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[728] | 144 | } |
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[730] | 145 | if (_data[idx].next != -1) { |
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| 146 | _data[_data[idx].next].prev = idx; |
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[728] | 147 | } |
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[730] | 148 | _iim[_data[idx].item] = idx; |
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[728] | 149 | } |
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[730] | 150 | _data.pop_back(); |
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[728] | 151 | } |
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| 152 | |
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| 153 | void unlace(int idx) { |
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[730] | 154 | if (_data[idx].prev != -1) { |
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| 155 | _data[_data[idx].prev].next = _data[idx].next; |
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[728] | 156 | } else { |
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[730] | 157 | _first[_data[idx].value] = _data[idx].next; |
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[728] | 158 | } |
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[730] | 159 | if (_data[idx].next != -1) { |
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| 160 | _data[_data[idx].next].prev = _data[idx].prev; |
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[728] | 161 | } |
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| 162 | } |
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| 163 | |
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| 164 | void lace(int idx) { |
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[730] | 165 | if (int(_first.size()) <= _data[idx].value) { |
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| 166 | _first.resize(_data[idx].value + 1, -1); |
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[728] | 167 | } |
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[730] | 168 | _data[idx].next = _first[_data[idx].value]; |
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| 169 | if (_data[idx].next != -1) { |
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| 170 | _data[_data[idx].next].prev = idx; |
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[728] | 171 | } |
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[730] | 172 | _first[_data[idx].value] = idx; |
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| 173 | _data[idx].prev = -1; |
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[728] | 174 | } |
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| 175 | |
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| 176 | public: |
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| 177 | /// \brief Insert a pair of item and priority into the heap. |
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| 178 | /// |
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| 179 | /// Adds \c p.first to the heap with priority \c p.second. |
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| 180 | /// \param p The pair to insert. |
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| 181 | void push(const Pair& p) { |
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| 182 | push(p.first, p.second); |
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| 183 | } |
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| 184 | |
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| 185 | /// \brief Insert an item into the heap with the given priority. |
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| 186 | /// |
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| 187 | /// Adds \c i to the heap with priority \c p. |
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| 188 | /// \param i The item to insert. |
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| 189 | /// \param p The priority of the item. |
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| 190 | void push(const Item &i, const Prio &p) { |
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[730] | 191 | int idx = _data.size(); |
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| 192 | _iim[i] = idx; |
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| 193 | _data.push_back(BucketItem(i, p)); |
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[728] | 194 | lace(idx); |
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[730] | 195 | if (Direction::less(p, _minimum)) { |
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| 196 | _minimum = p; |
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[728] | 197 | } |
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| 198 | } |
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| 199 | |
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| 200 | /// \brief Returns the item with minimum priority. |
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| 201 | /// |
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| 202 | /// This method returns the item with minimum priority. |
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| 203 | /// \pre The heap must be nonempty. |
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| 204 | Item top() const { |
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[730] | 205 | while (_first[_minimum] == -1) { |
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| 206 | Direction::increase(_minimum); |
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[728] | 207 | } |
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[730] | 208 | return _data[_first[_minimum]].item; |
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[728] | 209 | } |
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| 210 | |
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| 211 | /// \brief Returns the minimum priority. |
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| 212 | /// |
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| 213 | /// It returns the minimum priority. |
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| 214 | /// \pre The heap must be nonempty. |
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| 215 | Prio prio() const { |
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[730] | 216 | while (_first[_minimum] == -1) { |
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| 217 | Direction::increase(_minimum); |
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[728] | 218 | } |
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[730] | 219 | return _minimum; |
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[728] | 220 | } |
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| 221 | |
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| 222 | /// \brief Deletes the item with minimum priority. |
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| 223 | /// |
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| 224 | /// This method deletes the item with minimum priority from the heap. |
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| 225 | /// \pre The heap must be non-empty. |
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| 226 | void pop() { |
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[730] | 227 | while (_first[_minimum] == -1) { |
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| 228 | Direction::increase(_minimum); |
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[728] | 229 | } |
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[730] | 230 | int idx = _first[_minimum]; |
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| 231 | _iim[_data[idx].item] = -2; |
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[728] | 232 | unlace(idx); |
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| 233 | relocate_last(idx); |
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| 234 | } |
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| 235 | |
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| 236 | /// \brief Deletes \c i from the heap. |
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| 237 | /// |
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| 238 | /// This method deletes item \c i from the heap, if \c i was |
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| 239 | /// already stored in the heap. |
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| 240 | /// \param i The item to erase. |
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| 241 | void erase(const Item &i) { |
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[730] | 242 | int idx = _iim[i]; |
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| 243 | _iim[_data[idx].item] = -2; |
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[728] | 244 | unlace(idx); |
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| 245 | relocate_last(idx); |
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| 246 | } |
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| 247 | |
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| 248 | |
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| 249 | /// \brief Returns the priority of \c i. |
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| 250 | /// |
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| 251 | /// This function returns the priority of item \c i. |
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| 252 | /// \pre \c i must be in the heap. |
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| 253 | /// \param i The item. |
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| 254 | Prio operator[](const Item &i) const { |
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[730] | 255 | int idx = _iim[i]; |
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| 256 | return _data[idx].value; |
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[728] | 257 | } |
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| 258 | |
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| 259 | /// \brief \c i gets to the heap with priority \c p independently |
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| 260 | /// if \c i was already there. |
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| 261 | /// |
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| 262 | /// This method calls \ref push(\c i, \c p) if \c i is not stored |
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| 263 | /// in the heap and sets the priority of \c i to \c p otherwise. |
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| 264 | /// \param i The item. |
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| 265 | /// \param p The priority. |
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| 266 | void set(const Item &i, const Prio &p) { |
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[730] | 267 | int idx = _iim[i]; |
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[728] | 268 | if (idx < 0) { |
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[729] | 269 | push(i, p); |
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[730] | 270 | } else if (Direction::less(p, _data[idx].value)) { |
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[729] | 271 | decrease(i, p); |
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| 272 | } else { |
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[728] | 273 | increase(i, p); |
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| 274 | } |
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| 275 | } |
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| 276 | |
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| 277 | /// \brief Decreases the priority of \c i to \c p. |
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| 278 | /// |
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| 279 | /// This method decreases the priority of item \c i to \c p. |
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| 280 | /// \pre \c i must be stored in the heap with priority at least \c |
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| 281 | /// p relative to \c Compare. |
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| 282 | /// \param i The item. |
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| 283 | /// \param p The priority. |
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| 284 | void decrease(const Item &i, const Prio &p) { |
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[730] | 285 | int idx = _iim[i]; |
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[728] | 286 | unlace(idx); |
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[730] | 287 | _data[idx].value = p; |
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| 288 | if (Direction::less(p, _minimum)) { |
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| 289 | _minimum = p; |
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[728] | 290 | } |
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| 291 | lace(idx); |
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| 292 | } |
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| 293 | |
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| 294 | /// \brief Increases the priority of \c i to \c p. |
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| 295 | /// |
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| 296 | /// This method sets the priority of item \c i to \c p. |
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| 297 | /// \pre \c i must be stored in the heap with priority at most \c |
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| 298 | /// p relative to \c Compare. |
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| 299 | /// \param i The item. |
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| 300 | /// \param p The priority. |
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| 301 | void increase(const Item &i, const Prio &p) { |
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[730] | 302 | int idx = _iim[i]; |
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[728] | 303 | unlace(idx); |
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[730] | 304 | _data[idx].value = p; |
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[728] | 305 | lace(idx); |
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| 306 | } |
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| 307 | |
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| 308 | /// \brief Returns if \c item is in, has already been in, or has |
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| 309 | /// never been in the heap. |
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| 310 | /// |
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| 311 | /// This method returns PRE_HEAP if \c item has never been in the |
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| 312 | /// heap, IN_HEAP if it is in the heap at the moment, and POST_HEAP |
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| 313 | /// otherwise. In the latter case it is possible that \c item will |
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| 314 | /// get back to the heap again. |
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| 315 | /// \param i The item. |
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| 316 | State state(const Item &i) const { |
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[730] | 317 | int idx = _iim[i]; |
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[728] | 318 | if (idx >= 0) idx = 0; |
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| 319 | return State(idx); |
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| 320 | } |
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| 321 | |
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| 322 | /// \brief Sets the state of the \c item in the heap. |
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| 323 | /// |
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| 324 | /// Sets the state of the \c item in the heap. It can be used to |
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| 325 | /// manually clear the heap when it is important to achive the |
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| 326 | /// better time complexity. |
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| 327 | /// \param i The item. |
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| 328 | /// \param st The state. It should not be \c IN_HEAP. |
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| 329 | void state(const Item& i, State st) { |
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| 330 | switch (st) { |
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| 331 | case POST_HEAP: |
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| 332 | case PRE_HEAP: |
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| 333 | if (state(i) == IN_HEAP) { |
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| 334 | erase(i); |
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| 335 | } |
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[730] | 336 | _iim[i] = st; |
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[728] | 337 | break; |
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| 338 | case IN_HEAP: |
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| 339 | break; |
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| 340 | } |
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| 341 | } |
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| 342 | |
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| 343 | private: |
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| 344 | |
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| 345 | struct BucketItem { |
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| 346 | BucketItem(const Item& _item, int _value) |
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| 347 | : item(_item), value(_value) {} |
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| 348 | |
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| 349 | Item item; |
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| 350 | int value; |
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| 351 | |
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| 352 | int prev, next; |
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| 353 | }; |
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| 354 | |
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[730] | 355 | ItemIntMap& _iim; |
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| 356 | std::vector<int> _first; |
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| 357 | std::vector<BucketItem> _data; |
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| 358 | mutable int _minimum; |
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[728] | 359 | |
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| 360 | }; // class BucketHeap |
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| 361 | |
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| 362 | /// \ingroup auxdat |
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| 363 | /// |
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| 364 | /// \brief A Simplified Bucket Heap implementation. |
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| 365 | /// |
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| 366 | /// This class implements a simplified \e bucket \e heap data |
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| 367 | /// structure. It does not provide some functionality but it faster |
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| 368 | /// and simplier data structure than the BucketHeap. The main |
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| 369 | /// difference is that the BucketHeap stores for every key a double |
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| 370 | /// linked list while this class stores just simple lists. In the |
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[729] | 371 | /// other way it does not support erasing each elements just the |
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[728] | 372 | /// minimal and it does not supports key increasing, decreasing. |
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| 373 | /// |
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[730] | 374 | /// \param IM A read and write Item int map, used internally |
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[728] | 375 | /// to handle the cross references. |
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[730] | 376 | /// \param MIN If the given parameter is false then instead of the |
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| 377 | /// minimum value the maximum can be retrivied with the top() and |
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| 378 | /// prio() member functions. |
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[728] | 379 | /// |
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| 380 | /// \sa BucketHeap |
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[730] | 381 | template <typename IM, bool MIN = true > |
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[728] | 382 | class SimpleBucketHeap { |
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| 383 | |
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| 384 | public: |
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[730] | 385 | typedef typename IM::Key Item; |
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[728] | 386 | typedef int Prio; |
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| 387 | typedef std::pair<Item, Prio> Pair; |
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[730] | 388 | typedef IM ItemIntMap; |
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[728] | 389 | |
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[729] | 390 | private: |
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| 391 | |
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[730] | 392 | typedef _bucket_heap_bits::DirectionTraits<MIN> Direction; |
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[729] | 393 | |
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| 394 | public: |
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| 395 | |
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[728] | 396 | /// \brief Type to represent the items states. |
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| 397 | /// |
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| 398 | /// Each Item element have a state associated to it. It may be "in heap", |
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| 399 | /// "pre heap" or "post heap". The latter two are indifferent from the |
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| 400 | /// heap's point of view, but may be useful to the user. |
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| 401 | /// |
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[730] | 402 | /// The item-int map must be initialized in such way that it assigns |
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| 403 | /// \c PRE_HEAP (<tt>-1</tt>) to any element to be put in the heap. |
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[728] | 404 | enum State { |
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[730] | 405 | IN_HEAP = 0, ///< = 0. |
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| 406 | PRE_HEAP = -1, ///< = -1. |
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| 407 | POST_HEAP = -2 ///< = -2. |
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[728] | 408 | }; |
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| 409 | |
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| 410 | public: |
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| 411 | |
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| 412 | /// \brief The constructor. |
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| 413 | /// |
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| 414 | /// The constructor. |
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[730] | 415 | /// \param map should be given to the constructor, since it is used |
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[728] | 416 | /// internally to handle the cross references. The value of the map |
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| 417 | /// should be PRE_HEAP (-1) for each element. |
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[730] | 418 | explicit SimpleBucketHeap(ItemIntMap &map) |
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| 419 | : _iim(map), _free(-1), _num(0), _minimum(0) {} |
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[728] | 420 | |
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| 421 | /// \brief Returns the number of items stored in the heap. |
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| 422 | /// |
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| 423 | /// The number of items stored in the heap. |
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[730] | 424 | int size() const { return _num; } |
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[728] | 425 | |
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| 426 | /// \brief Checks if the heap stores no items. |
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| 427 | /// |
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| 428 | /// Returns \c true if and only if the heap stores no items. |
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[730] | 429 | bool empty() const { return _num == 0; } |
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[728] | 430 | |
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| 431 | /// \brief Make empty this heap. |
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| 432 | /// |
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| 433 | /// Make empty this heap. It does not change the cross reference |
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| 434 | /// map. If you want to reuse a heap what is not surely empty you |
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| 435 | /// should first clear the heap and after that you should set the |
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| 436 | /// cross reference map for each item to \c PRE_HEAP. |
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| 437 | void clear() { |
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[730] | 438 | _data.clear(); _first.clear(); _free = -1; _num = 0; _minimum = 0; |
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[728] | 439 | } |
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| 440 | |
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| 441 | /// \brief Insert a pair of item and priority into the heap. |
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| 442 | /// |
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| 443 | /// Adds \c p.first to the heap with priority \c p.second. |
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| 444 | /// \param p The pair to insert. |
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| 445 | void push(const Pair& p) { |
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| 446 | push(p.first, p.second); |
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| 447 | } |
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| 448 | |
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| 449 | /// \brief Insert an item into the heap with the given priority. |
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| 450 | /// |
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| 451 | /// Adds \c i to the heap with priority \c p. |
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| 452 | /// \param i The item to insert. |
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| 453 | /// \param p The priority of the item. |
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| 454 | void push(const Item &i, const Prio &p) { |
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| 455 | int idx; |
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[730] | 456 | if (_free == -1) { |
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| 457 | idx = _data.size(); |
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| 458 | _data.push_back(BucketItem(i)); |
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[728] | 459 | } else { |
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[730] | 460 | idx = _free; |
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| 461 | _free = _data[idx].next; |
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| 462 | _data[idx].item = i; |
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[728] | 463 | } |
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[730] | 464 | _iim[i] = idx; |
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| 465 | if (p >= int(_first.size())) _first.resize(p + 1, -1); |
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| 466 | _data[idx].next = _first[p]; |
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| 467 | _first[p] = idx; |
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| 468 | if (Direction::less(p, _minimum)) { |
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| 469 | _minimum = p; |
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[728] | 470 | } |
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[730] | 471 | ++_num; |
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[728] | 472 | } |
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| 473 | |
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| 474 | /// \brief Returns the item with minimum priority. |
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| 475 | /// |
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| 476 | /// This method returns the item with minimum priority. |
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| 477 | /// \pre The heap must be nonempty. |
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| 478 | Item top() const { |
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[730] | 479 | while (_first[_minimum] == -1) { |
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| 480 | Direction::increase(_minimum); |
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[728] | 481 | } |
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[730] | 482 | return _data[_first[_minimum]].item; |
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[728] | 483 | } |
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| 484 | |
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| 485 | /// \brief Returns the minimum priority. |
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| 486 | /// |
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| 487 | /// It returns the minimum priority. |
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| 488 | /// \pre The heap must be nonempty. |
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| 489 | Prio prio() const { |
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[730] | 490 | while (_first[_minimum] == -1) { |
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| 491 | Direction::increase(_minimum); |
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[728] | 492 | } |
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[730] | 493 | return _minimum; |
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[728] | 494 | } |
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| 495 | |
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| 496 | /// \brief Deletes the item with minimum priority. |
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| 497 | /// |
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| 498 | /// This method deletes the item with minimum priority from the heap. |
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| 499 | /// \pre The heap must be non-empty. |
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| 500 | void pop() { |
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[730] | 501 | while (_first[_minimum] == -1) { |
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| 502 | Direction::increase(_minimum); |
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[728] | 503 | } |
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[730] | 504 | int idx = _first[_minimum]; |
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| 505 | _iim[_data[idx].item] = -2; |
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| 506 | _first[_minimum] = _data[idx].next; |
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| 507 | _data[idx].next = _free; |
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| 508 | _free = idx; |
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| 509 | --_num; |
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[728] | 510 | } |
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| 511 | |
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| 512 | /// \brief Returns the priority of \c i. |
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| 513 | /// |
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| 514 | /// This function returns the priority of item \c i. |
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| 515 | /// \warning This operator is not a constant time function |
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| 516 | /// because it scans the whole data structure to find the proper |
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| 517 | /// value. |
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| 518 | /// \pre \c i must be in the heap. |
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| 519 | /// \param i The item. |
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| 520 | Prio operator[](const Item &i) const { |
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[730] | 521 | for (int k = 0; k < _first.size(); ++k) { |
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| 522 | int idx = _first[k]; |
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[728] | 523 | while (idx != -1) { |
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[730] | 524 | if (_data[idx].item == i) { |
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[728] | 525 | return k; |
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| 526 | } |
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[730] | 527 | idx = _data[idx].next; |
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[728] | 528 | } |
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| 529 | } |
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| 530 | return -1; |
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| 531 | } |
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| 532 | |
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| 533 | /// \brief Returns if \c item is in, has already been in, or has |
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| 534 | /// never been in the heap. |
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| 535 | /// |
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| 536 | /// This method returns PRE_HEAP if \c item has never been in the |
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| 537 | /// heap, IN_HEAP if it is in the heap at the moment, and POST_HEAP |
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| 538 | /// otherwise. In the latter case it is possible that \c item will |
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| 539 | /// get back to the heap again. |
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| 540 | /// \param i The item. |
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| 541 | State state(const Item &i) const { |
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[730] | 542 | int idx = _iim[i]; |
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[728] | 543 | if (idx >= 0) idx = 0; |
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| 544 | return State(idx); |
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| 545 | } |
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| 546 | |
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| 547 | private: |
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| 548 | |
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| 549 | struct BucketItem { |
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| 550 | BucketItem(const Item& _item) |
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| 551 | : item(_item) {} |
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| 552 | |
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| 553 | Item item; |
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| 554 | int next; |
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| 555 | }; |
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| 556 | |
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[730] | 557 | ItemIntMap& _iim; |
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| 558 | std::vector<int> _first; |
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| 559 | std::vector<BucketItem> _data; |
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| 560 | int _free, _num; |
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| 561 | mutable int _minimum; |
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[728] | 562 | |
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| 563 | }; // class SimpleBucketHeap |
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| 564 | |
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| 565 | } |
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| 566 | |
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| 567 | #endif |
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