[2038] | 1 | /* -*- C++ -*- |
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| 2 | * |
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| 3 | * This file is a part of LEMON, a generic C++ optimization library |
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| 4 | * |
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| 5 | * Copyright (C) 2003-2006 |
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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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| 32 | /// \ingroup auxdat |
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| 33 | |
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| 34 | /// \brief A Bucket Heap implementation. |
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| 35 | /// |
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| 36 | /// This class implements the \e bucket \e heap data structure. A \e heap |
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| 37 | /// is a data structure for storing items with specified values called \e |
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| 38 | /// priorities in such a way that finding the item with minimum priority is |
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| 39 | /// efficient. The bucket heap is very simple implementation, it can store |
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[2042] | 40 | /// only integer priorities and it stores for each priority in the |
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| 41 | /// \f$ [0..C) \f$ range a list of items. So it should be used only when |
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| 42 | /// the priorities are small. It is not intended to use as dijkstra heap. |
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[2038] | 43 | /// |
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| 44 | /// \param _Item Type of the items to be stored. |
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| 45 | /// \param _ItemIntMap A read and writable Item int map, used internally |
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| 46 | /// to handle the cross references. |
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| 47 | /// \param minimize If the given parameter is true then the heap gives back |
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| 48 | /// the lowest priority. |
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| 49 | template <typename _Item, typename _ItemIntMap, bool minimize = true > |
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| 50 | class BucketHeap { |
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| 51 | |
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| 52 | public: |
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| 53 | typedef _Item Item; |
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| 54 | typedef int Prio; |
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| 55 | typedef std::pair<Item, Prio> Pair; |
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| 56 | typedef _ItemIntMap ItemIntMap; |
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| 57 | |
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| 58 | /// \brief Type to represent the items states. |
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| 59 | /// |
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| 60 | /// Each Item element have a state associated to it. It may be "in heap", |
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| 61 | /// "pre heap" or "post heap". The latter two are indifferent from the |
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| 62 | /// heap's point of view, but may be useful to the user. |
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| 63 | /// |
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| 64 | /// The ItemIntMap \e should be initialized in such way that it maps |
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| 65 | /// PRE_HEAP (-1) to any element to be put in the heap... |
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| 66 | enum state_enum { |
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| 67 | IN_HEAP = 0, |
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| 68 | PRE_HEAP = -1, |
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| 69 | POST_HEAP = -2 |
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| 70 | }; |
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| 71 | |
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| 72 | public: |
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| 73 | /// \brief The constructor. |
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| 74 | /// |
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| 75 | /// The constructor. |
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| 76 | /// \param _index should be given to the constructor, since it is used |
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| 77 | /// internally to handle the cross references. The value of the map |
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| 78 | /// should be PRE_HEAP (-1) for each element. |
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| 79 | explicit BucketHeap(ItemIntMap &_index) : index(_index), minimal(0) {} |
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| 80 | |
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| 81 | /// The number of items stored in the heap. |
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| 82 | /// |
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| 83 | /// \brief Returns the number of items stored in the heap. |
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| 84 | int size() const { return data.size(); } |
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| 85 | |
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| 86 | /// \brief Checks if the heap stores no items. |
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| 87 | /// |
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| 88 | /// Returns \c true if and only if the heap stores no items. |
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| 89 | bool empty() const { return data.empty(); } |
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| 90 | |
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| 91 | /// \brief Make empty this heap. |
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| 92 | /// |
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[2050] | 93 | /// Make empty this heap. It does not change the cross reference |
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| 94 | /// map. If you want to reuse a heap what is not surely empty you |
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| 95 | /// should first clear the heap and after that you should set the |
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| 96 | /// cross reference map for each item to \c PRE_HEAP. |
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[2038] | 97 | void clear() { |
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| 98 | data.clear(); first.clear(); minimal = 0; |
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| 99 | } |
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| 100 | |
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| 101 | private: |
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| 102 | |
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| 103 | void relocate_last(int idx) { |
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| 104 | if (idx + 1 < (int)data.size()) { |
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| 105 | data[idx] = data.back(); |
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| 106 | if (data[idx].prev != -1) { |
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| 107 | data[data[idx].prev].next = idx; |
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| 108 | } else { |
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| 109 | first[data[idx].value] = idx; |
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| 110 | } |
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| 111 | if (data[idx].next != -1) { |
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| 112 | data[data[idx].next].prev = idx; |
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| 113 | } |
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| 114 | index[data[idx].item] = idx; |
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| 115 | } |
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| 116 | data.pop_back(); |
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| 117 | } |
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| 118 | |
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| 119 | void unlace(int idx) { |
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| 120 | if (data[idx].prev != -1) { |
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| 121 | data[data[idx].prev].next = data[idx].next; |
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| 122 | } else { |
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| 123 | first[data[idx].value] = data[idx].next; |
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| 124 | } |
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| 125 | if (data[idx].next != -1) { |
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| 126 | data[data[idx].next].prev = data[idx].prev; |
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| 127 | } |
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| 128 | } |
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| 129 | |
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| 130 | void lace(int idx) { |
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| 131 | if ((int)first.size() <= data[idx].value) { |
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| 132 | first.resize(data[idx].value + 1, -1); |
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| 133 | } |
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| 134 | data[idx].next = first[data[idx].value]; |
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| 135 | if (data[idx].next != -1) { |
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| 136 | data[data[idx].next].prev = idx; |
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| 137 | } |
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| 138 | first[data[idx].value] = idx; |
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| 139 | data[idx].prev = -1; |
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| 140 | } |
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| 141 | |
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| 142 | public: |
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| 143 | /// \brief Insert a pair of item and priority into the heap. |
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| 144 | /// |
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| 145 | /// Adds \c p.first to the heap with priority \c p.second. |
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| 146 | /// \param p The pair to insert. |
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| 147 | void push(const Pair& p) { |
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| 148 | push(p.first, p.second); |
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| 149 | } |
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| 150 | |
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| 151 | /// \brief Insert an item into the heap with the given priority. |
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| 152 | /// |
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| 153 | /// Adds \c i to the heap with priority \c p. |
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| 154 | /// \param i The item to insert. |
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| 155 | /// \param p The priority of the item. |
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| 156 | void push(const Item &i, const Prio &p) { |
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| 157 | int idx = data.size(); |
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| 158 | index[i] = idx; |
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| 159 | data.push_back(BucketItem(i, p)); |
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| 160 | lace(idx); |
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| 161 | if (p < minimal) { |
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| 162 | minimal = p; |
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| 163 | } |
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| 164 | } |
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| 165 | |
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| 166 | /// \brief Returns the item with minimum priority. |
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| 167 | /// |
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| 168 | /// This method returns the item with minimum priority. |
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| 169 | /// \pre The heap must be nonempty. |
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| 170 | Item top() const { |
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| 171 | while (first[minimal] == -1) { |
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| 172 | ++minimal; |
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| 173 | } |
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| 174 | return data[first[minimal]].item; |
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| 175 | } |
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| 176 | |
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| 177 | /// \brief Returns the minimum priority. |
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| 178 | /// |
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| 179 | /// It returns the minimum priority. |
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| 180 | /// \pre The heap must be nonempty. |
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| 181 | Prio prio() const { |
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| 182 | while (first[minimal] == -1) { |
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| 183 | ++minimal; |
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| 184 | } |
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| 185 | return minimal; |
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| 186 | } |
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| 187 | |
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| 188 | /// \brief Deletes the item with minimum priority. |
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| 189 | /// |
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| 190 | /// This method deletes the item with minimum priority from the heap. |
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| 191 | /// \pre The heap must be non-empty. |
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| 192 | void pop() { |
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| 193 | while (first[minimal] == -1) { |
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| 194 | ++minimal; |
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| 195 | } |
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| 196 | int idx = first[minimal]; |
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| 197 | index[data[idx].item] = -2; |
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| 198 | unlace(idx); |
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| 199 | relocate_last(idx); |
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| 200 | } |
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| 201 | |
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| 202 | /// \brief Deletes \c i from the heap. |
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| 203 | /// |
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| 204 | /// This method deletes item \c i from the heap, if \c i was |
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| 205 | /// already stored in the heap. |
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| 206 | /// \param i The item to erase. |
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| 207 | void erase(const Item &i) { |
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| 208 | int idx = index[i]; |
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| 209 | index[data[idx].item] = -2; |
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| 210 | unlace(idx); |
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| 211 | relocate_last(idx); |
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| 212 | } |
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| 213 | |
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| 214 | |
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| 215 | /// \brief Returns the priority of \c i. |
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| 216 | /// |
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| 217 | /// This function returns the priority of item \c i. |
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| 218 | /// \pre \c i must be in the heap. |
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| 219 | /// \param i The item. |
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| 220 | Prio operator[](const Item &i) const { |
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| 221 | int idx = index[i]; |
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| 222 | return data[idx].value; |
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| 223 | } |
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| 224 | |
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| 225 | /// \brief \c i gets to the heap with priority \c p independently |
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| 226 | /// if \c i was already there. |
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| 227 | /// |
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| 228 | /// This method calls \ref push(\c i, \c p) if \c i is not stored |
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| 229 | /// in the heap and sets the priority of \c i to \c p otherwise. |
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| 230 | /// \param i The item. |
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| 231 | /// \param p The priority. |
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| 232 | void set(const Item &i, const Prio &p) { |
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| 233 | int idx = index[i]; |
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| 234 | if (idx < 0) { |
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| 235 | push(i,p); |
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| 236 | } else if (p > data[idx].value) { |
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| 237 | increase(i, p); |
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| 238 | } else { |
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| 239 | decrease(i, p); |
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| 240 | } |
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| 241 | } |
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| 242 | |
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| 243 | /// \brief Decreases the priority of \c i to \c p. |
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| 244 | |
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| 245 | /// This method decreases the priority of item \c i to \c p. |
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| 246 | /// \pre \c i must be stored in the heap with priority at least \c |
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| 247 | /// p relative to \c Compare. |
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| 248 | /// \param i The item. |
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| 249 | /// \param p The priority. |
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| 250 | void decrease(const Item &i, const Prio &p) { |
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| 251 | int idx = index[i]; |
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| 252 | unlace(idx); |
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| 253 | data[idx].value = p; |
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| 254 | if (p < minimal) { |
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| 255 | minimal = p; |
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| 256 | } |
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| 257 | lace(idx); |
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| 258 | } |
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| 259 | |
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| 260 | /// \brief Increases the priority of \c i to \c p. |
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| 261 | /// |
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| 262 | /// This method sets the priority of item \c i to \c p. |
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| 263 | /// \pre \c i must be stored in the heap with priority at most \c |
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| 264 | /// p relative to \c Compare. |
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| 265 | /// \param i The item. |
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| 266 | /// \param p The priority. |
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| 267 | void increase(const Item &i, const Prio &p) { |
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| 268 | int idx = index[i]; |
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| 269 | unlace(idx); |
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| 270 | data[idx].value = p; |
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| 271 | lace(idx); |
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| 272 | } |
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| 273 | |
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| 274 | /// \brief Returns if \c item is in, has already been in, or has |
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| 275 | /// never been in the heap. |
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| 276 | /// |
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| 277 | /// This method returns PRE_HEAP if \c item has never been in the |
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| 278 | /// heap, IN_HEAP if it is in the heap at the moment, and POST_HEAP |
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| 279 | /// otherwise. In the latter case it is possible that \c item will |
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| 280 | /// get back to the heap again. |
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| 281 | /// \param i The item. |
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| 282 | state_enum state(const Item &i) const { |
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| 283 | int idx = index[i]; |
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| 284 | if (idx >= 0) idx = 0; |
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| 285 | return state_enum(idx); |
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| 286 | } |
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| 287 | |
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| 288 | /// \brief Sets the state of the \c item in the heap. |
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| 289 | /// |
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| 290 | /// Sets the state of the \c item in the heap. It can be used to |
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| 291 | /// manually clear the heap when it is important to achive the |
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| 292 | /// better time complexity. |
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| 293 | /// \param i The item. |
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| 294 | /// \param st The state. It should not be \c IN_HEAP. |
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| 295 | void state(const Item& i, state_enum st) { |
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| 296 | switch (st) { |
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| 297 | case POST_HEAP: |
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| 298 | case PRE_HEAP: |
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| 299 | if (state(i) == IN_HEAP) { |
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| 300 | erase(i); |
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| 301 | } |
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| 302 | index[i] = st; |
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| 303 | break; |
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| 304 | case IN_HEAP: |
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| 305 | break; |
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| 306 | } |
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| 307 | } |
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| 308 | |
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| 309 | private: |
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| 310 | |
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| 311 | struct BucketItem { |
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| 312 | BucketItem(const Item& _item, int _value) |
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| 313 | : item(_item), value(_value) {} |
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| 314 | |
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| 315 | Item item; |
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| 316 | int value; |
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| 317 | |
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| 318 | int prev, next; |
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| 319 | }; |
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| 320 | |
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| 321 | ItemIntMap& index; |
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| 322 | std::vector<int> first; |
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| 323 | std::vector<BucketItem> data; |
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| 324 | mutable int minimal; |
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| 325 | |
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| 326 | }; // class BucketHeap |
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| 327 | |
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| 328 | |
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| 329 | template <typename _Item, typename _ItemIntMap> |
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| 330 | class BucketHeap<_Item, _ItemIntMap, false> { |
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| 331 | |
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| 332 | public: |
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| 333 | typedef _Item Item; |
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| 334 | typedef int Prio; |
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| 335 | typedef std::pair<Item, Prio> Pair; |
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| 336 | typedef _ItemIntMap ItemIntMap; |
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| 337 | |
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| 338 | enum state_enum { |
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| 339 | IN_HEAP = 0, |
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| 340 | PRE_HEAP = -1, |
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| 341 | POST_HEAP = -2 |
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| 342 | }; |
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| 343 | |
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| 344 | public: |
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| 345 | |
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| 346 | explicit BucketHeap(ItemIntMap &_index) : index(_index), maximal(-1) {} |
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| 347 | |
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| 348 | int size() const { return data.size(); } |
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| 349 | bool empty() const { return data.empty(); } |
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| 350 | |
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| 351 | void clear() { |
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| 352 | data.clear(); first.clear(); maximal = -1; |
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| 353 | } |
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| 354 | |
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| 355 | private: |
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| 356 | |
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| 357 | void relocate_last(int idx) { |
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| 358 | if (idx + 1 != (int)data.size()) { |
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| 359 | data[idx] = data.back(); |
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| 360 | if (data[idx].prev != -1) { |
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| 361 | data[data[idx].prev].next = idx; |
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| 362 | } else { |
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| 363 | first[data[idx].value] = idx; |
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| 364 | } |
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| 365 | if (data[idx].next != -1) { |
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| 366 | data[data[idx].next].prev = idx; |
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| 367 | } |
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| 368 | index[data[idx].item] = idx; |
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| 369 | } |
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| 370 | data.pop_back(); |
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| 371 | } |
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| 372 | |
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| 373 | void unlace(int idx) { |
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| 374 | if (data[idx].prev != -1) { |
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| 375 | data[data[idx].prev].next = data[idx].next; |
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| 376 | } else { |
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| 377 | first[data[idx].value] = data[idx].next; |
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| 378 | } |
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| 379 | if (data[idx].next != -1) { |
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| 380 | data[data[idx].next].prev = data[idx].prev; |
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| 381 | } |
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| 382 | } |
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| 383 | |
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| 384 | void lace(int idx) { |
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| 385 | if ((int)first.size() <= data[idx].value) { |
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| 386 | first.resize(data[idx].value + 1, -1); |
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| 387 | } |
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| 388 | data[idx].next = first[data[idx].value]; |
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| 389 | if (data[idx].next != -1) { |
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| 390 | data[data[idx].next].prev = idx; |
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| 391 | } |
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| 392 | first[data[idx].value] = idx; |
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| 393 | data[idx].prev = -1; |
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| 394 | } |
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| 395 | |
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| 396 | public: |
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| 397 | |
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| 398 | void push(const Pair& p) { |
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| 399 | push(p.first, p.second); |
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| 400 | } |
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| 401 | |
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| 402 | void push(const Item &i, const Prio &p) { |
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| 403 | int idx = data.size(); |
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| 404 | index[i] = idx; |
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| 405 | data.push_back(BucketItem(i, p)); |
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| 406 | lace(idx); |
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| 407 | if (data[idx].value > maximal) { |
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| 408 | maximal = data[idx].value; |
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| 409 | } |
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| 410 | } |
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| 411 | |
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| 412 | Item top() const { |
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| 413 | while (first[maximal] == -1) { |
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| 414 | --maximal; |
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| 415 | } |
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| 416 | return data[first[maximal]].item; |
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| 417 | } |
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| 418 | |
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| 419 | Prio prio() const { |
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| 420 | while (first[maximal] == -1) { |
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| 421 | --maximal; |
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| 422 | } |
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| 423 | return maximal; |
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| 424 | } |
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| 425 | |
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| 426 | void pop() { |
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| 427 | while (first[maximal] == -1) { |
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| 428 | --maximal; |
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| 429 | } |
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| 430 | int idx = first[maximal]; |
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| 431 | index[data[idx].item] = -2; |
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| 432 | unlace(idx); |
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| 433 | relocate_last(idx); |
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| 434 | } |
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| 435 | |
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| 436 | void erase(const Item &i) { |
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| 437 | int idx = index[i]; |
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| 438 | index[data[idx].item] = -2; |
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| 439 | unlace(idx); |
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| 440 | relocate_last(idx); |
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| 441 | } |
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| 442 | |
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| 443 | Prio operator[](const Item &i) const { |
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| 444 | int idx = index[i]; |
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| 445 | return data[idx].value; |
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| 446 | } |
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| 447 | |
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| 448 | void set(const Item &i, const Prio &p) { |
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| 449 | int idx = index[i]; |
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| 450 | if (idx < 0) { |
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| 451 | push(i,p); |
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| 452 | } else if (p > data[idx].value) { |
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| 453 | decrease(i, p); |
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| 454 | } else { |
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| 455 | increase(i, p); |
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| 456 | } |
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| 457 | } |
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| 458 | |
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| 459 | void decrease(const Item &i, const Prio &p) { |
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| 460 | int idx = index[i]; |
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| 461 | unlace(idx); |
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| 462 | data[idx].value = p; |
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| 463 | if (p > maximal) { |
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| 464 | maximal = p; |
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| 465 | } |
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| 466 | lace(idx); |
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| 467 | } |
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| 468 | |
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| 469 | void increase(const Item &i, const Prio &p) { |
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| 470 | int idx = index[i]; |
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| 471 | unlace(idx); |
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| 472 | data[idx].value = p; |
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| 473 | lace(idx); |
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| 474 | } |
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| 475 | |
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| 476 | state_enum state(const Item &i) const { |
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| 477 | int idx = index[i]; |
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| 478 | if (idx >= 0) idx = 0; |
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| 479 | return state_enum(idx); |
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| 480 | } |
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| 481 | |
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| 482 | void state(const Item& i, state_enum st) { |
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| 483 | switch (st) { |
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| 484 | case POST_HEAP: |
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| 485 | case PRE_HEAP: |
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| 486 | if (state(i) == IN_HEAP) { |
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| 487 | erase(i); |
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| 488 | } |
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| 489 | index[i] = st; |
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| 490 | break; |
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| 491 | case IN_HEAP: |
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| 492 | break; |
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| 493 | } |
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| 494 | } |
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| 495 | |
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| 496 | private: |
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| 497 | |
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| 498 | struct BucketItem { |
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| 499 | BucketItem(const Item& _item, int _value) |
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| 500 | : item(_item), value(_value) {} |
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| 501 | |
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| 502 | Item item; |
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| 503 | int value; |
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| 504 | |
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| 505 | int prev, next; |
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| 506 | }; |
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| 507 | |
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| 508 | ItemIntMap& index; |
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| 509 | std::vector<int> first; |
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| 510 | std::vector<BucketItem> data; |
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| 511 | mutable int maximal; |
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| 512 | |
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| 513 | }; // class BucketHeap |
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| 514 | |
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| 515 | } |
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| 516 | |
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| 517 | #endif |
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