[681] | 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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[682] | 32 | namespace _bucket_heap_bits { |
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| 33 | |
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| 34 | template <bool minimize> |
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| 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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[681] | 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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| 68 | /// \param _ItemIntMap A read and writable Item int map, used internally |
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| 69 | /// to handle the cross references. |
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| 70 | /// \param minimize If the given parameter is true then the heap gives back |
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| 71 | /// the lowest priority. |
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[682] | 72 | template <typename _ItemIntMap, bool minimize = true> |
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[681] | 73 | class BucketHeap { |
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| 74 | |
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| 75 | public: |
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| 76 | /// \e |
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| 77 | typedef typename _ItemIntMap::Key Item; |
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| 78 | /// \e |
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| 79 | typedef int Prio; |
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| 80 | /// \e |
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| 81 | typedef std::pair<Item, Prio> Pair; |
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| 82 | /// \e |
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| 83 | typedef _ItemIntMap ItemIntMap; |
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| 84 | |
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[682] | 85 | private: |
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| 86 | |
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| 87 | typedef _bucket_heap_bits::DirectionTraits<minimize> Direction; |
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| 88 | |
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| 89 | public: |
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| 90 | |
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[681] | 91 | /// \brief Type to represent the items states. |
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| 92 | /// |
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| 93 | /// Each Item element have a state associated to it. It may be "in heap", |
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| 94 | /// "pre heap" or "post heap". The latter two are indifferent from the |
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| 95 | /// heap's point of view, but may be useful to the user. |
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| 96 | /// |
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| 97 | /// The ItemIntMap \e should be initialized in such way that it maps |
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| 98 | /// PRE_HEAP (-1) to any element to be put in the heap... |
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| 99 | enum State { |
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| 100 | IN_HEAP = 0, |
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| 101 | PRE_HEAP = -1, |
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| 102 | POST_HEAP = -2 |
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| 103 | }; |
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| 104 | |
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| 105 | public: |
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| 106 | /// \brief The constructor. |
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| 107 | /// |
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| 108 | /// The constructor. |
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| 109 | /// \param _index should be given to the constructor, since it is used |
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| 110 | /// internally to handle the cross references. The value of the map |
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| 111 | /// should be PRE_HEAP (-1) for each element. |
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| 112 | explicit BucketHeap(ItemIntMap &_index) : index(_index), minimal(0) {} |
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| 113 | |
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| 114 | /// The number of items stored in the heap. |
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| 115 | /// |
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| 116 | /// \brief Returns the number of items stored in the heap. |
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| 117 | int size() const { return data.size(); } |
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| 118 | |
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| 119 | /// \brief Checks if the heap stores no items. |
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| 120 | /// |
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| 121 | /// Returns \c true if and only if the heap stores no items. |
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| 122 | bool empty() const { return data.empty(); } |
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| 123 | |
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| 124 | /// \brief Make empty this heap. |
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| 125 | /// |
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| 126 | /// Make empty this heap. It does not change the cross reference |
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| 127 | /// map. If you want to reuse a heap what is not surely empty you |
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| 128 | /// should first clear the heap and after that you should set the |
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| 129 | /// cross reference map for each item to \c PRE_HEAP. |
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| 130 | void clear() { |
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| 131 | data.clear(); first.clear(); minimal = 0; |
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| 132 | } |
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| 133 | |
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| 134 | private: |
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| 135 | |
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| 136 | void relocate_last(int idx) { |
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| 137 | if (idx + 1 < int(data.size())) { |
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| 138 | data[idx] = data.back(); |
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| 139 | if (data[idx].prev != -1) { |
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| 140 | data[data[idx].prev].next = idx; |
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| 141 | } else { |
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| 142 | first[data[idx].value] = idx; |
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| 143 | } |
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| 144 | if (data[idx].next != -1) { |
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| 145 | data[data[idx].next].prev = idx; |
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| 146 | } |
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| 147 | index[data[idx].item] = idx; |
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| 148 | } |
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| 149 | data.pop_back(); |
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| 150 | } |
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| 151 | |
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| 152 | void unlace(int idx) { |
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| 153 | if (data[idx].prev != -1) { |
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| 154 | data[data[idx].prev].next = data[idx].next; |
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| 155 | } else { |
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| 156 | first[data[idx].value] = data[idx].next; |
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| 157 | } |
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| 158 | if (data[idx].next != -1) { |
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| 159 | data[data[idx].next].prev = data[idx].prev; |
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| 160 | } |
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| 161 | } |
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| 162 | |
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| 163 | void lace(int idx) { |
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| 164 | if (int(first.size()) <= data[idx].value) { |
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| 165 | first.resize(data[idx].value + 1, -1); |
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| 166 | } |
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| 167 | data[idx].next = first[data[idx].value]; |
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| 168 | if (data[idx].next != -1) { |
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| 169 | data[data[idx].next].prev = idx; |
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| 170 | } |
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| 171 | first[data[idx].value] = idx; |
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| 172 | data[idx].prev = -1; |
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| 173 | } |
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| 174 | |
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| 175 | public: |
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| 176 | /// \brief Insert a pair of item and priority into the heap. |
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| 177 | /// |
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| 178 | /// Adds \c p.first to the heap with priority \c p.second. |
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| 179 | /// \param p The pair to insert. |
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| 180 | void push(const Pair& p) { |
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| 181 | push(p.first, p.second); |
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| 182 | } |
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| 183 | |
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| 184 | /// \brief Insert an item into the heap with the given priority. |
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| 185 | /// |
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| 186 | /// Adds \c i to the heap with priority \c p. |
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| 187 | /// \param i The item to insert. |
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| 188 | /// \param p The priority of the item. |
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| 189 | void push(const Item &i, const Prio &p) { |
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| 190 | int idx = data.size(); |
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| 191 | index[i] = idx; |
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| 192 | data.push_back(BucketItem(i, p)); |
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| 193 | lace(idx); |
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[682] | 194 | if (Direction::less(p, minimal)) { |
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[681] | 195 | minimal = p; |
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| 196 | } |
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| 197 | } |
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| 198 | |
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| 199 | /// \brief Returns the item with minimum priority. |
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| 200 | /// |
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| 201 | /// This method returns the item with minimum priority. |
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| 202 | /// \pre The heap must be nonempty. |
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| 203 | Item top() const { |
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| 204 | while (first[minimal] == -1) { |
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[682] | 205 | Direction::increase(minimal); |
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[681] | 206 | } |
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| 207 | return data[first[minimal]].item; |
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| 208 | } |
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| 209 | |
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| 210 | /// \brief Returns the minimum priority. |
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| 211 | /// |
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| 212 | /// It returns the minimum priority. |
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| 213 | /// \pre The heap must be nonempty. |
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| 214 | Prio prio() const { |
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| 215 | while (first[minimal] == -1) { |
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[682] | 216 | Direction::increase(minimal); |
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[681] | 217 | } |
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| 218 | return minimal; |
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| 219 | } |
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| 220 | |
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| 221 | /// \brief Deletes the item with minimum priority. |
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| 222 | /// |
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| 223 | /// This method deletes the item with minimum priority from the heap. |
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| 224 | /// \pre The heap must be non-empty. |
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| 225 | void pop() { |
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| 226 | while (first[minimal] == -1) { |
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[682] | 227 | Direction::increase(minimal); |
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[681] | 228 | } |
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| 229 | int idx = first[minimal]; |
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| 230 | index[data[idx].item] = -2; |
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| 231 | unlace(idx); |
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| 232 | relocate_last(idx); |
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| 233 | } |
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| 234 | |
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| 235 | /// \brief Deletes \c i from the heap. |
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| 236 | /// |
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| 237 | /// This method deletes item \c i from the heap, if \c i was |
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| 238 | /// already stored in the heap. |
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| 239 | /// \param i The item to erase. |
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| 240 | void erase(const Item &i) { |
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| 241 | int idx = index[i]; |
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| 242 | index[data[idx].item] = -2; |
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| 243 | unlace(idx); |
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| 244 | relocate_last(idx); |
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| 245 | } |
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| 246 | |
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| 247 | |
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| 248 | /// \brief Returns the priority of \c i. |
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| 249 | /// |
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| 250 | /// This function returns the priority of item \c i. |
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| 251 | /// \pre \c i must be in the heap. |
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| 252 | /// \param i The item. |
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| 253 | Prio operator[](const Item &i) const { |
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| 254 | int idx = index[i]; |
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| 255 | return data[idx].value; |
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| 256 | } |
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| 257 | |
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| 258 | /// \brief \c i gets to the heap with priority \c p independently |
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| 259 | /// if \c i was already there. |
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| 260 | /// |
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| 261 | /// This method calls \ref push(\c i, \c p) if \c i is not stored |
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| 262 | /// in the heap and sets the priority of \c i to \c p otherwise. |
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| 263 | /// \param i The item. |
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| 264 | /// \param p The priority. |
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| 265 | void set(const Item &i, const Prio &p) { |
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| 266 | int idx = index[i]; |
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| 267 | if (idx < 0) { |
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[682] | 268 | push(i, p); |
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| 269 | } else if (Direction::less(p, data[idx].value)) { |
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| 270 | decrease(i, p); |
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| 271 | } else { |
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[681] | 272 | increase(i, p); |
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| 273 | } |
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| 274 | } |
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| 275 | |
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| 276 | /// \brief Decreases the priority of \c i to \c p. |
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| 277 | /// |
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| 278 | /// This method decreases the priority of item \c i to \c p. |
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| 279 | /// \pre \c i must be stored in the heap with priority at least \c |
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| 280 | /// p relative to \c Compare. |
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| 281 | /// \param i The item. |
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| 282 | /// \param p The priority. |
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| 283 | void decrease(const Item &i, const Prio &p) { |
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| 284 | int idx = index[i]; |
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| 285 | unlace(idx); |
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| 286 | data[idx].value = p; |
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[682] | 287 | if (Direction::less(p, minimal)) { |
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[681] | 288 | minimal = p; |
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| 289 | } |
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| 290 | lace(idx); |
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| 291 | } |
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| 292 | |
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| 293 | /// \brief Increases the priority of \c i to \c p. |
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| 294 | /// |
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| 295 | /// This method sets the priority of item \c i to \c p. |
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| 296 | /// \pre \c i must be stored in the heap with priority at most \c |
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| 297 | /// p relative to \c Compare. |
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| 298 | /// \param i The item. |
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| 299 | /// \param p The priority. |
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| 300 | void increase(const Item &i, const Prio &p) { |
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| 301 | int idx = index[i]; |
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| 302 | unlace(idx); |
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| 303 | data[idx].value = p; |
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| 304 | lace(idx); |
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| 305 | } |
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| 306 | |
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| 307 | /// \brief Returns if \c item is in, has already been in, or has |
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| 308 | /// never been in the heap. |
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| 309 | /// |
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| 310 | /// This method returns PRE_HEAP if \c item has never been in the |
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| 311 | /// heap, IN_HEAP if it is in the heap at the moment, and POST_HEAP |
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| 312 | /// otherwise. In the latter case it is possible that \c item will |
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| 313 | /// get back to the heap again. |
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| 314 | /// \param i The item. |
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| 315 | State state(const Item &i) const { |
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| 316 | int idx = index[i]; |
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| 317 | if (idx >= 0) idx = 0; |
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| 318 | return State(idx); |
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| 319 | } |
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| 320 | |
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| 321 | /// \brief Sets the state of the \c item in the heap. |
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| 322 | /// |
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| 323 | /// Sets the state of the \c item in the heap. It can be used to |
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| 324 | /// manually clear the heap when it is important to achive the |
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| 325 | /// better time complexity. |
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| 326 | /// \param i The item. |
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| 327 | /// \param st The state. It should not be \c IN_HEAP. |
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| 328 | void state(const Item& i, State st) { |
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| 329 | switch (st) { |
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| 330 | case POST_HEAP: |
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| 331 | case PRE_HEAP: |
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| 332 | if (state(i) == IN_HEAP) { |
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| 333 | erase(i); |
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| 334 | } |
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| 335 | index[i] = st; |
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| 336 | break; |
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| 337 | case IN_HEAP: |
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| 338 | break; |
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| 339 | } |
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| 340 | } |
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| 341 | |
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| 342 | private: |
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| 343 | |
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| 344 | struct BucketItem { |
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| 345 | BucketItem(const Item& _item, int _value) |
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| 346 | : item(_item), value(_value) {} |
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| 347 | |
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| 348 | Item item; |
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| 349 | int value; |
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| 350 | |
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| 351 | int prev, next; |
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| 352 | }; |
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| 353 | |
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| 354 | ItemIntMap& index; |
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| 355 | std::vector<int> first; |
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| 356 | std::vector<BucketItem> data; |
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| 357 | mutable int minimal; |
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| 358 | |
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| 359 | }; // class BucketHeap |
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| 360 | |
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| 361 | /// \ingroup auxdat |
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| 362 | /// |
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| 363 | /// \brief A Simplified Bucket Heap implementation. |
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| 364 | /// |
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| 365 | /// This class implements a simplified \e bucket \e heap data |
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| 366 | /// structure. It does not provide some functionality but it faster |
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| 367 | /// and simplier data structure than the BucketHeap. The main |
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| 368 | /// difference is that the BucketHeap stores for every key a double |
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| 369 | /// linked list while this class stores just simple lists. In the |
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[682] | 370 | /// other way it does not support erasing each elements just the |
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[681] | 371 | /// minimal and it does not supports key increasing, decreasing. |
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| 372 | /// |
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| 373 | /// \param _ItemIntMap A read and writable Item int map, used internally |
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| 374 | /// to handle the cross references. |
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| 375 | /// \param minimize If the given parameter is true then the heap gives back |
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| 376 | /// the lowest priority. |
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| 377 | /// |
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| 378 | /// \sa BucketHeap |
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| 379 | template <typename _ItemIntMap, bool minimize = true > |
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| 380 | class SimpleBucketHeap { |
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| 381 | |
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| 382 | public: |
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| 383 | typedef typename _ItemIntMap::Key Item; |
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| 384 | typedef int Prio; |
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| 385 | typedef std::pair<Item, Prio> Pair; |
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| 386 | typedef _ItemIntMap ItemIntMap; |
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| 387 | |
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[682] | 388 | private: |
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| 389 | |
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| 390 | typedef _bucket_heap_bits::DirectionTraits<minimize> Direction; |
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| 391 | |
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| 392 | public: |
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| 393 | |
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[681] | 394 | /// \brief Type to represent the items states. |
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| 395 | /// |
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| 396 | /// Each Item element have a state associated to it. It may be "in heap", |
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| 397 | /// "pre heap" or "post heap". The latter two are indifferent from the |
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| 398 | /// heap's point of view, but may be useful to the user. |
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| 399 | /// |
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| 400 | /// The ItemIntMap \e should be initialized in such way that it maps |
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| 401 | /// PRE_HEAP (-1) to any element to be put in the heap... |
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| 402 | enum State { |
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| 403 | IN_HEAP = 0, |
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| 404 | PRE_HEAP = -1, |
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| 405 | POST_HEAP = -2 |
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| 406 | }; |
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| 407 | |
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| 408 | public: |
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| 409 | |
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| 410 | /// \brief The constructor. |
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| 411 | /// |
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| 412 | /// The constructor. |
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| 413 | /// \param _index should be given to the constructor, since it is used |
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| 414 | /// internally to handle the cross references. The value of the map |
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| 415 | /// should be PRE_HEAP (-1) for each element. |
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| 416 | explicit SimpleBucketHeap(ItemIntMap &_index) |
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| 417 | : index(_index), free(-1), num(0), minimal(0) {} |
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| 418 | |
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| 419 | /// \brief Returns the number of items stored in the heap. |
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| 420 | /// |
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| 421 | /// The number of items stored in the heap. |
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| 422 | int size() const { return num; } |
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| 423 | |
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| 424 | /// \brief Checks if the heap stores no items. |
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| 425 | /// |
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| 426 | /// Returns \c true if and only if the heap stores no items. |
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| 427 | bool empty() const { return num == 0; } |
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| 428 | |
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| 429 | /// \brief Make empty this heap. |
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| 430 | /// |
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| 431 | /// Make empty this heap. It does not change the cross reference |
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| 432 | /// map. If you want to reuse a heap what is not surely empty you |
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| 433 | /// should first clear the heap and after that you should set the |
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| 434 | /// cross reference map for each item to \c PRE_HEAP. |
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| 435 | void clear() { |
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| 436 | data.clear(); first.clear(); free = -1; num = 0; minimal = 0; |
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| 437 | } |
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| 438 | |
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| 439 | /// \brief Insert a pair of item and priority into the heap. |
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| 440 | /// |
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| 441 | /// Adds \c p.first to the heap with priority \c p.second. |
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| 442 | /// \param p The pair to insert. |
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| 443 | void push(const Pair& p) { |
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| 444 | push(p.first, p.second); |
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| 445 | } |
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| 446 | |
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| 447 | /// \brief Insert an item into the heap with the given priority. |
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| 448 | /// |
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| 449 | /// Adds \c i to the heap with priority \c p. |
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| 450 | /// \param i The item to insert. |
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| 451 | /// \param p The priority of the item. |
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| 452 | void push(const Item &i, const Prio &p) { |
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| 453 | int idx; |
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| 454 | if (free == -1) { |
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| 455 | idx = data.size(); |
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| 456 | data.push_back(BucketItem(i)); |
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| 457 | } else { |
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| 458 | idx = free; |
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| 459 | free = data[idx].next; |
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| 460 | data[idx].item = i; |
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| 461 | } |
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| 462 | index[i] = idx; |
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| 463 | if (p >= int(first.size())) first.resize(p + 1, -1); |
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| 464 | data[idx].next = first[p]; |
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| 465 | first[p] = idx; |
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[682] | 466 | if (Direction::less(p, minimal)) { |
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[681] | 467 | minimal = p; |
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| 468 | } |
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| 469 | ++num; |
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| 470 | } |
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| 471 | |
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| 472 | /// \brief Returns the item with minimum priority. |
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| 473 | /// |
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| 474 | /// This method returns the item with minimum priority. |
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| 475 | /// \pre The heap must be nonempty. |
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| 476 | Item top() const { |
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| 477 | while (first[minimal] == -1) { |
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[682] | 478 | Direction::increase(minimal); |
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[681] | 479 | } |
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| 480 | return data[first[minimal]].item; |
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| 481 | } |
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| 482 | |
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| 483 | /// \brief Returns the minimum priority. |
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| 484 | /// |
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| 485 | /// It returns the minimum priority. |
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| 486 | /// \pre The heap must be nonempty. |
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| 487 | Prio prio() const { |
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| 488 | while (first[minimal] == -1) { |
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[682] | 489 | Direction::increase(minimal); |
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[681] | 490 | } |
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| 491 | return minimal; |
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| 492 | } |
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| 493 | |
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| 494 | /// \brief Deletes the item with minimum priority. |
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| 495 | /// |
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| 496 | /// This method deletes the item with minimum priority from the heap. |
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| 497 | /// \pre The heap must be non-empty. |
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| 498 | void pop() { |
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| 499 | while (first[minimal] == -1) { |
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[682] | 500 | Direction::increase(minimal); |
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[681] | 501 | } |
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| 502 | int idx = first[minimal]; |
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| 503 | index[data[idx].item] = -2; |
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| 504 | first[minimal] = data[idx].next; |
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| 505 | data[idx].next = free; |
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| 506 | free = idx; |
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| 507 | --num; |
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| 508 | } |
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| 509 | |
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| 510 | /// \brief Returns the priority of \c i. |
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| 511 | /// |
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| 512 | /// This function returns the priority of item \c i. |
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| 513 | /// \warning This operator is not a constant time function |
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| 514 | /// because it scans the whole data structure to find the proper |
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| 515 | /// value. |
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| 516 | /// \pre \c i must be in the heap. |
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| 517 | /// \param i The item. |
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| 518 | Prio operator[](const Item &i) const { |
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| 519 | for (int k = 0; k < first.size(); ++k) { |
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| 520 | int idx = first[k]; |
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| 521 | while (idx != -1) { |
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| 522 | if (data[idx].item == i) { |
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| 523 | return k; |
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| 524 | } |
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| 525 | idx = data[idx].next; |
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| 526 | } |
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| 527 | } |
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| 528 | return -1; |
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| 529 | } |
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| 530 | |
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| 531 | /// \brief Returns if \c item is in, has already been in, or has |
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| 532 | /// never been in the heap. |
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| 533 | /// |
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| 534 | /// This method returns PRE_HEAP if \c item has never been in the |
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| 535 | /// heap, IN_HEAP if it is in the heap at the moment, and POST_HEAP |
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| 536 | /// otherwise. In the latter case it is possible that \c item will |
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| 537 | /// get back to the heap again. |
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| 538 | /// \param i The item. |
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| 539 | State state(const Item &i) const { |
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| 540 | int idx = index[i]; |
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| 541 | if (idx >= 0) idx = 0; |
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| 542 | return State(idx); |
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| 543 | } |
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| 544 | |
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| 545 | private: |
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| 546 | |
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| 547 | struct BucketItem { |
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| 548 | BucketItem(const Item& _item) |
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| 549 | : item(_item) {} |
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| 550 | |
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| 551 | Item item; |
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| 552 | int next; |
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| 553 | }; |
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| 554 | |
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| 555 | ItemIntMap& index; |
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| 556 | std::vector<int> first; |
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| 557 | std::vector<BucketItem> data; |
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| 558 | int free, num; |
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| 559 | mutable int minimal; |
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| 560 | |
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| 561 | }; // class SimpleBucketHeap |
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| 562 | |
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| 563 | } |
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| 564 | |
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| 565 | #endif |
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