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Diffstat (limited to 'extern/quadriflow/3rd/lemon-1.3.1/lemon/radix_heap.h')
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diff --git a/extern/quadriflow/3rd/lemon-1.3.1/lemon/radix_heap.h b/extern/quadriflow/3rd/lemon-1.3.1/lemon/radix_heap.h new file mode 100644 index 00000000000..8701ce7474a --- /dev/null +++ b/extern/quadriflow/3rd/lemon-1.3.1/lemon/radix_heap.h @@ -0,0 +1,438 @@ +/* -*- mode: C++; indent-tabs-mode: nil; -*- + * + * This file is a part of LEMON, a generic C++ optimization library. + * + * Copyright (C) 2003-2009 + * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport + * (Egervary Research Group on Combinatorial Optimization, EGRES). + * + * Permission to use, modify and distribute this software is granted + * provided that this copyright notice appears in all copies. For + * precise terms see the accompanying LICENSE file. + * + * This software is provided "AS IS" with no warranty of any kind, + * express or implied, and with no claim as to its suitability for any + * purpose. + * + */ + +#ifndef LEMON_RADIX_HEAP_H +#define LEMON_RADIX_HEAP_H + +///\ingroup heaps +///\file +///\brief Radix heap implementation. + +#include <vector> +#include <lemon/error.h> + +namespace lemon { + + + /// \ingroup heaps + /// + /// \brief Radix heap data structure. + /// + /// This class implements the \e radix \e heap data structure. + /// It practically conforms to the \ref concepts::Heap "heap concept", + /// but it has some limitations due its special implementation. + /// The type of the priorities must be \c int and the priority of an + /// item cannot be decreased under the priority of the last removed item. + /// + /// \tparam IM A read-writable item map with \c int values, used + /// internally to handle the cross references. + template <typename IM> + class RadixHeap { + + public: + + /// Type of the item-int map. + typedef IM ItemIntMap; + /// Type of the priorities. + typedef int Prio; + /// Type of the items stored in the heap. + typedef typename ItemIntMap::Key Item; + + /// \brief Exception thrown by RadixHeap. + /// + /// This exception is thrown when an item is inserted into a + /// RadixHeap with a priority smaller than the last erased one. + /// \see RadixHeap + class PriorityUnderflowError : public Exception { + public: + virtual const char* what() const throw() { + return "lemon::RadixHeap::PriorityUnderflowError"; + } + }; + + /// \brief Type to represent the states of the items. + /// + /// Each item has a state associated to it. It can be "in heap", + /// "pre-heap" or "post-heap". The latter two are indifferent from the + /// heap's point of view, but may be useful to the user. + /// + /// The item-int map must be initialized in such way that it assigns + /// \c PRE_HEAP (<tt>-1</tt>) to any element to be put in the heap. + enum State { + IN_HEAP = 0, ///< = 0. + PRE_HEAP = -1, ///< = -1. + POST_HEAP = -2 ///< = -2. + }; + + private: + + struct RadixItem { + int prev, next, box; + Item item; + int prio; + RadixItem(Item _item, int _prio) : item(_item), prio(_prio) {} + }; + + struct RadixBox { + int first; + int min, size; + RadixBox(int _min, int _size) : first(-1), min(_min), size(_size) {} + }; + + std::vector<RadixItem> _data; + std::vector<RadixBox> _boxes; + + ItemIntMap &_iim; + + public: + + /// \brief Constructor. + /// + /// Constructor. + /// \param map A map that assigns \c int values to the items. + /// It is used internally to handle the cross references. + /// The assigned value must be \c PRE_HEAP (<tt>-1</tt>) for each item. + /// \param minimum The initial minimum value of the heap. + /// \param capacity The initial capacity of the heap. + RadixHeap(ItemIntMap &map, int minimum = 0, int capacity = 0) + : _iim(map) + { + _boxes.push_back(RadixBox(minimum, 1)); + _boxes.push_back(RadixBox(minimum + 1, 1)); + while (lower(_boxes.size() - 1, capacity + minimum - 1)) { + extend(); + } + } + + /// \brief The number of items stored in the heap. + /// + /// This function returns the number of items stored in the heap. + int size() const { return _data.size(); } + + /// \brief Check if the heap is empty. + /// + /// This function returns \c true if the heap is empty. + bool empty() const { return _data.empty(); } + + /// \brief Make the heap empty. + /// + /// This functon makes the heap empty. + /// It does not change the cross reference map. If you want to reuse + /// a heap that is not surely empty, you should first clear it and + /// then you should set the cross reference map to \c PRE_HEAP + /// for each item. + /// \param minimum The minimum value of the heap. + /// \param capacity The capacity of the heap. + void clear(int minimum = 0, int capacity = 0) { + _data.clear(); _boxes.clear(); + _boxes.push_back(RadixBox(minimum, 1)); + _boxes.push_back(RadixBox(minimum + 1, 1)); + while (lower(_boxes.size() - 1, capacity + minimum - 1)) { + extend(); + } + } + + private: + + bool upper(int box, Prio pr) { + return pr < _boxes[box].min; + } + + bool lower(int box, Prio pr) { + return pr >= _boxes[box].min + _boxes[box].size; + } + + // Remove item from the box list + void remove(int index) { + if (_data[index].prev >= 0) { + _data[_data[index].prev].next = _data[index].next; + } else { + _boxes[_data[index].box].first = _data[index].next; + } + if (_data[index].next >= 0) { + _data[_data[index].next].prev = _data[index].prev; + } + } + + // Insert item into the box list + void insert(int box, int index) { + if (_boxes[box].first == -1) { + _boxes[box].first = index; + _data[index].next = _data[index].prev = -1; + } else { + _data[index].next = _boxes[box].first; + _data[_boxes[box].first].prev = index; + _data[index].prev = -1; + _boxes[box].first = index; + } + _data[index].box = box; + } + + // Add a new box to the box list + void extend() { + int min = _boxes.back().min + _boxes.back().size; + int bs = 2 * _boxes.back().size; + _boxes.push_back(RadixBox(min, bs)); + } + + // Move an item up into the proper box. + void bubbleUp(int index) { + if (!lower(_data[index].box, _data[index].prio)) return; + remove(index); + int box = findUp(_data[index].box, _data[index].prio); + insert(box, index); + } + + // Find up the proper box for the item with the given priority + int findUp(int start, int pr) { + while (lower(start, pr)) { + if (++start == int(_boxes.size())) { + extend(); + } + } + return start; + } + + // Move an item down into the proper box + void bubbleDown(int index) { + if (!upper(_data[index].box, _data[index].prio)) return; + remove(index); + int box = findDown(_data[index].box, _data[index].prio); + insert(box, index); + } + + // Find down the proper box for the item with the given priority + int findDown(int start, int pr) { + while (upper(start, pr)) { + if (--start < 0) throw PriorityUnderflowError(); + } + return start; + } + + // Find the first non-empty box + int findFirst() { + int first = 0; + while (_boxes[first].first == -1) ++first; + return first; + } + + // Gives back the minimum priority of the given box + int minValue(int box) { + int min = _data[_boxes[box].first].prio; + for (int k = _boxes[box].first; k != -1; k = _data[k].next) { + if (_data[k].prio < min) min = _data[k].prio; + } + return min; + } + + // Rearrange the items of the heap and make the first box non-empty + void moveDown() { + int box = findFirst(); + if (box == 0) return; + int min = minValue(box); + for (int i = 0; i <= box; ++i) { + _boxes[i].min = min; + min += _boxes[i].size; + } + int curr = _boxes[box].first, next; + while (curr != -1) { + next = _data[curr].next; + bubbleDown(curr); + curr = next; + } + } + + void relocateLast(int index) { + if (index != int(_data.size()) - 1) { + _data[index] = _data.back(); + if (_data[index].prev != -1) { + _data[_data[index].prev].next = index; + } else { + _boxes[_data[index].box].first = index; + } + if (_data[index].next != -1) { + _data[_data[index].next].prev = index; + } + _iim[_data[index].item] = index; + } + _data.pop_back(); + } + + public: + + /// \brief Insert an item into the heap with the given priority. + /// + /// This function inserts the given item into the heap with the + /// given priority. + /// \param i The item to insert. + /// \param p The priority of the item. + /// \pre \e i must not be stored in the heap. + /// \warning This method may throw an \c UnderFlowPriorityException. + void push(const Item &i, const Prio &p) { + int n = _data.size(); + _iim.set(i, n); + _data.push_back(RadixItem(i, p)); + while (lower(_boxes.size() - 1, p)) { + extend(); + } + int box = findDown(_boxes.size() - 1, p); + insert(box, n); + } + + /// \brief Return the item having minimum priority. + /// + /// This function returns the item having minimum priority. + /// \pre The heap must be non-empty. + Item top() const { + const_cast<RadixHeap<ItemIntMap>&>(*this).moveDown(); + return _data[_boxes[0].first].item; + } + + /// \brief The minimum priority. + /// + /// This function returns the minimum priority. + /// \pre The heap must be non-empty. + Prio prio() const { + const_cast<RadixHeap<ItemIntMap>&>(*this).moveDown(); + return _data[_boxes[0].first].prio; + } + + /// \brief Remove the item having minimum priority. + /// + /// This function removes the item having minimum priority. + /// \pre The heap must be non-empty. + void pop() { + moveDown(); + int index = _boxes[0].first; + _iim[_data[index].item] = POST_HEAP; + remove(index); + relocateLast(index); + } + + /// \brief Remove the given item from the heap. + /// + /// This function removes the given item from the heap if it is + /// already stored. + /// \param i The item to delete. + /// \pre \e i must be in the heap. + void erase(const Item &i) { + int index = _iim[i]; + _iim[i] = POST_HEAP; + remove(index); + relocateLast(index); + } + + /// \brief The priority of the given item. + /// + /// This function returns the priority of the given item. + /// \param i The item. + /// \pre \e i must be in the heap. + Prio operator[](const Item &i) const { + int idx = _iim[i]; + return _data[idx].prio; + } + + /// \brief Set the priority of an item or insert it, if it is + /// not stored in the heap. + /// + /// This method sets the priority of the given item if it is + /// already stored in the heap. Otherwise it inserts the given + /// item into the heap with the given priority. + /// \param i The item. + /// \param p The priority. + /// \pre \e i must be in the heap. + /// \warning This method may throw an \c UnderFlowPriorityException. + void set(const Item &i, const Prio &p) { + int idx = _iim[i]; + if( idx < 0 ) { + push(i, p); + } + else if( p >= _data[idx].prio ) { + _data[idx].prio = p; + bubbleUp(idx); + } else { + _data[idx].prio = p; + bubbleDown(idx); + } + } + + /// \brief Decrease the priority of an item to the given value. + /// + /// This function decreases the priority of an item to the given value. + /// \param i The item. + /// \param p The priority. + /// \pre \e i must be stored in the heap with priority at least \e p. + /// \warning This method may throw an \c UnderFlowPriorityException. + void decrease(const Item &i, const Prio &p) { + int idx = _iim[i]; + _data[idx].prio = p; + bubbleDown(idx); + } + + /// \brief Increase the priority of an item to the given value. + /// + /// This function increases the priority of an item to the given value. + /// \param i The item. + /// \param p The priority. + /// \pre \e i must be stored in the heap with priority at most \e p. + void increase(const Item &i, const Prio &p) { + int idx = _iim[i]; + _data[idx].prio = p; + bubbleUp(idx); + } + + /// \brief Return the state of an item. + /// + /// This method returns \c PRE_HEAP if the given item has never + /// been in the heap, \c IN_HEAP if it is in the heap at the moment, + /// and \c POST_HEAP otherwise. + /// In the latter case it is possible that the item will get back + /// to the heap again. + /// \param i The item. + State state(const Item &i) const { + int s = _iim[i]; + if( s >= 0 ) s = 0; + return State(s); + } + + /// \brief Set the state of an item in the heap. + /// + /// This function sets the state of the given item in the heap. + /// It can be used to manually clear the heap when it is important + /// to achive better time complexity. + /// \param i The item. + /// \param st The state. It should not be \c IN_HEAP. + void state(const Item& i, State st) { + switch (st) { + case POST_HEAP: + case PRE_HEAP: + if (state(i) == IN_HEAP) { + erase(i); + } + _iim[i] = st; + break; + case IN_HEAP: + break; + } + } + + }; // class RadixHeap + +} // namespace lemon + +#endif // LEMON_RADIX_HEAP_H |