deba@681: /* -*- mode: C++; indent-tabs-mode: nil; -*-
deba@681: *
deba@681: * This file is a part of LEMON, a generic C++ optimization library.
deba@681: *
deba@681: * Copyright (C) 2003-2009
deba@681: * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
deba@681: * (Egervary Research Group on Combinatorial Optimization, EGRES).
deba@681: *
deba@681: * Permission to use, modify and distribute this software is granted
deba@681: * provided that this copyright notice appears in all copies. For
deba@681: * precise terms see the accompanying LICENSE file.
deba@681: *
deba@681: * This software is provided "AS IS" with no warranty of any kind,
deba@681: * express or implied, and with no claim as to its suitability for any
deba@681: * purpose.
deba@681: *
deba@681: */
deba@681:
deba@681: #ifndef LEMON_BUCKET_HEAP_H
deba@681: #define LEMON_BUCKET_HEAP_H
deba@681:
kpeter@710: ///\ingroup heaps
deba@681: ///\file
kpeter@709: ///\brief Bucket heap implementation.
deba@681:
deba@681: #include <vector>
deba@681: #include <utility>
deba@681: #include <functional>
deba@681:
deba@681: namespace lemon {
deba@681:
deba@682: namespace _bucket_heap_bits {
deba@682:
deba@683: template <bool MIN>
deba@682: struct DirectionTraits {
deba@682: static bool less(int left, int right) {
deba@682: return left < right;
deba@682: }
deba@682: static void increase(int& value) {
deba@682: ++value;
deba@682: }
deba@682: };
deba@682:
deba@682: template <>
deba@682: struct DirectionTraits<false> {
deba@682: static bool less(int left, int right) {
deba@682: return left > right;
deba@682: }
deba@682: static void increase(int& value) {
deba@682: --value;
deba@682: }
deba@682: };
deba@682:
deba@682: }
deba@682:
kpeter@710: /// \ingroup heaps
deba@681: ///
kpeter@709: /// \brief Bucket heap data structure.
deba@681: ///
kpeter@709: /// This class implements the \e bucket \e heap data structure.
kpeter@709: /// It practically conforms to the \ref concepts::Heap "heap concept",
kpeter@709: /// but it has some limitations.
deba@681: ///
kpeter@709: /// The bucket heap is a very simple structure. It can store only
kpeter@709: /// \c int priorities and it maintains a list of items for each priority
kpeter@709: /// in the range <tt>[0..C)</tt>. So it should only be used when the
kpeter@709: /// priorities are small. It is not intended to use as a Dijkstra heap.
kpeter@709: ///
kpeter@709: /// \tparam IM A read-writable item map with \c int values, used
kpeter@709: /// internally to handle the cross references.
kpeter@709: /// \tparam MIN Indicate if the heap is a \e min-heap or a \e max-heap.
kpeter@709: /// The default is \e min-heap. If this parameter is set to \c false,
kpeter@709: /// then the comparison is reversed, so the top(), prio() and pop()
kpeter@709: /// functions deal with the item having maximum priority instead of the
kpeter@709: /// minimum.
kpeter@709: ///
kpeter@709: /// \sa SimpleBucketHeap
deba@683: template <typename IM, bool MIN = true>
deba@681: class BucketHeap {
deba@681:
deba@681: public:
kpeter@709:
kpeter@709: /// Type of the item-int map.
kpeter@709: typedef IM ItemIntMap;
kpeter@709: /// Type of the priorities.
deba@681: typedef int Prio;
kpeter@709: /// Type of the items stored in the heap.
kpeter@709: typedef typename ItemIntMap::Key Item;
kpeter@709: /// Type of the item-priority pairs.
kpeter@709: typedef std::pair<Item,Prio> Pair;
deba@681:
deba@682: private:
deba@682:
deba@683: typedef _bucket_heap_bits::DirectionTraits<MIN> Direction;
deba@682:
deba@682: public:
deba@682:
kpeter@709: /// \brief Type to represent the states of the items.
deba@681: ///
kpeter@709: /// Each item has a state associated to it. It can be "in heap",
kpeter@709: /// "pre-heap" or "post-heap". The latter two are indifferent from the
deba@681: /// heap's point of view, but may be useful to the user.
deba@681: ///
deba@683: /// The item-int map must be initialized in such way that it assigns
deba@683: /// \c PRE_HEAP (<tt>-1</tt>) to any element to be put in the heap.
deba@681: enum State {
deba@683: IN_HEAP = 0, ///< = 0.
deba@683: PRE_HEAP = -1, ///< = -1.
deba@683: POST_HEAP = -2 ///< = -2.
deba@681: };
deba@681:
deba@681: public:
kpeter@709:
kpeter@709: /// \brief Constructor.
deba@681: ///
kpeter@709: /// Constructor.
kpeter@709: /// \param map A map that assigns \c int values to the items.
kpeter@709: /// It is used internally to handle the cross references.
kpeter@709: /// The assigned value must be \c PRE_HEAP (<tt>-1</tt>) for each item.
deba@683: explicit BucketHeap(ItemIntMap &map) : _iim(map), _minimum(0) {}
deba@681:
kpeter@709: /// \brief The number of items stored in the heap.
deba@681: ///
kpeter@709: /// This function returns the number of items stored in the heap.
deba@683: int size() const { return _data.size(); }
deba@681:
kpeter@709: /// \brief Check if the heap is empty.
deba@681: ///
kpeter@709: /// This function returns \c true if the heap is empty.
deba@683: bool empty() const { return _data.empty(); }
deba@681:
kpeter@709: /// \brief Make the heap empty.
deba@681: ///
kpeter@709: /// This functon makes the heap empty.
kpeter@709: /// It does not change the cross reference map. If you want to reuse
kpeter@709: /// a heap that is not surely empty, you should first clear it and
kpeter@709: /// then you should set the cross reference map to \c PRE_HEAP
kpeter@709: /// for each item.
deba@681: void clear() {
deba@683: _data.clear(); _first.clear(); _minimum = 0;
deba@681: }
deba@681:
deba@681: private:
deba@681:
kpeter@711: void relocateLast(int idx) {
deba@683: if (idx + 1 < int(_data.size())) {
deba@683: _data[idx] = _data.back();
deba@683: if (_data[idx].prev != -1) {
deba@683: _data[_data[idx].prev].next = idx;
deba@681: } else {
deba@683: _first[_data[idx].value] = idx;
deba@681: }
deba@683: if (_data[idx].next != -1) {
deba@683: _data[_data[idx].next].prev = idx;
deba@681: }
deba@683: _iim[_data[idx].item] = idx;
deba@681: }
deba@683: _data.pop_back();
deba@681: }
deba@681:
deba@681: void unlace(int idx) {
deba@683: if (_data[idx].prev != -1) {
deba@683: _data[_data[idx].prev].next = _data[idx].next;
deba@681: } else {
deba@683: _first[_data[idx].value] = _data[idx].next;
deba@681: }
deba@683: if (_data[idx].next != -1) {
deba@683: _data[_data[idx].next].prev = _data[idx].prev;
deba@681: }
deba@681: }
deba@681:
deba@681: void lace(int idx) {
deba@683: if (int(_first.size()) <= _data[idx].value) {
deba@683: _first.resize(_data[idx].value + 1, -1);
deba@681: }
deba@683: _data[idx].next = _first[_data[idx].value];
deba@683: if (_data[idx].next != -1) {
deba@683: _data[_data[idx].next].prev = idx;
deba@681: }
deba@683: _first[_data[idx].value] = idx;
deba@683: _data[idx].prev = -1;
deba@681: }
deba@681:
deba@681: public:
kpeter@709:
deba@681: /// \brief Insert a pair of item and priority into the heap.
deba@681: ///
kpeter@709: /// This function inserts \c p.first to the heap with priority
kpeter@709: /// \c p.second.
deba@681: /// \param p The pair to insert.
kpeter@709: /// \pre \c p.first must not be stored in the heap.
deba@681: void push(const Pair& p) {
deba@681: push(p.first, p.second);
deba@681: }
deba@681:
deba@681: /// \brief Insert an item into the heap with the given priority.
deba@681: ///
kpeter@709: /// This function inserts the given item into the heap with the
kpeter@709: /// given priority.
deba@681: /// \param i The item to insert.
deba@681: /// \param p The priority of the item.
kpeter@709: /// \pre \e i must not be stored in the heap.
deba@681: void push(const Item &i, const Prio &p) {
deba@683: int idx = _data.size();
deba@683: _iim[i] = idx;
deba@683: _data.push_back(BucketItem(i, p));
deba@681: lace(idx);
deba@683: if (Direction::less(p, _minimum)) {
deba@683: _minimum = p;
deba@681: }
deba@681: }
deba@681:
kpeter@709: /// \brief Return the item having minimum priority.
deba@681: ///
kpeter@709: /// This function returns the item having minimum priority.
kpeter@709: /// \pre The heap must be non-empty.
deba@681: Item top() const {
deba@683: while (_first[_minimum] == -1) {
deba@683: Direction::increase(_minimum);
deba@681: }
deba@683: return _data[_first[_minimum]].item;
deba@681: }
deba@681:
kpeter@709: /// \brief The minimum priority.
deba@681: ///
kpeter@709: /// This function returns the minimum priority.
kpeter@709: /// \pre The heap must be non-empty.
deba@681: Prio prio() const {
deba@683: while (_first[_minimum] == -1) {
deba@683: Direction::increase(_minimum);
deba@681: }
deba@683: return _minimum;
deba@681: }
deba@681:
kpeter@709: /// \brief Remove the item having minimum priority.
deba@681: ///
kpeter@709: /// This function removes the item having minimum priority.
deba@681: /// \pre The heap must be non-empty.
deba@681: void pop() {
deba@683: while (_first[_minimum] == -1) {
deba@683: Direction::increase(_minimum);
deba@681: }
deba@683: int idx = _first[_minimum];
deba@683: _iim[_data[idx].item] = -2;
deba@681: unlace(idx);
kpeter@711: relocateLast(idx);
deba@681: }
deba@681:
kpeter@709: /// \brief Remove the given item from the heap.
deba@681: ///
kpeter@709: /// This function removes the given item from the heap if it is
kpeter@709: /// already stored.
kpeter@709: /// \param i The item to delete.
kpeter@709: /// \pre \e i must be in the heap.
deba@681: void erase(const Item &i) {
deba@683: int idx = _iim[i];
deba@683: _iim[_data[idx].item] = -2;
deba@681: unlace(idx);
kpeter@711: relocateLast(idx);
deba@681: }
deba@681:
kpeter@709: /// \brief The priority of the given item.
deba@681: ///
kpeter@709: /// This function returns the priority of the given item.
deba@681: /// \param i The item.
kpeter@709: /// \pre \e i must be in the heap.
deba@681: Prio operator[](const Item &i) const {
deba@683: int idx = _iim[i];
deba@683: return _data[idx].value;
deba@681: }
deba@681:
kpeter@709: /// \brief Set the priority of an item or insert it, if it is
kpeter@709: /// not stored in the heap.
deba@681: ///
kpeter@709: /// This method sets the priority of the given item if it is
kpeter@709: /// already stored in the heap. Otherwise it inserts the given
kpeter@709: /// item into the heap with the given priority.
deba@681: /// \param i The item.
deba@681: /// \param p The priority.
deba@681: void set(const Item &i, const Prio &p) {
deba@683: int idx = _iim[i];
deba@681: if (idx < 0) {
deba@682: push(i, p);
deba@683: } else if (Direction::less(p, _data[idx].value)) {
deba@682: decrease(i, p);
deba@682: } else {
deba@681: increase(i, p);
deba@681: }
deba@681: }
deba@681:
kpeter@709: /// \brief Decrease the priority of an item to the given value.
deba@681: ///
kpeter@709: /// This function decreases the priority of an item to the given value.
deba@681: /// \param i The item.
deba@681: /// \param p The priority.
kpeter@709: /// \pre \e i must be stored in the heap with priority at least \e p.
deba@681: void decrease(const Item &i, const Prio &p) {
deba@683: int idx = _iim[i];
deba@681: unlace(idx);
deba@683: _data[idx].value = p;
deba@683: if (Direction::less(p, _minimum)) {
deba@683: _minimum = p;
deba@681: }
deba@681: lace(idx);
deba@681: }
deba@681:
kpeter@709: /// \brief Increase the priority of an item to the given value.
deba@681: ///
kpeter@709: /// This function increases the priority of an item to the given value.
deba@681: /// \param i The item.
deba@681: /// \param p The priority.
kpeter@709: /// \pre \e i must be stored in the heap with priority at most \e p.
deba@681: void increase(const Item &i, const Prio &p) {
deba@683: int idx = _iim[i];
deba@681: unlace(idx);
deba@683: _data[idx].value = p;
deba@681: lace(idx);
deba@681: }
deba@681:
kpeter@709: /// \brief Return the state of an item.
deba@681: ///
kpeter@709: /// This method returns \c PRE_HEAP if the given item has never
kpeter@709: /// been in the heap, \c IN_HEAP if it is in the heap at the moment,
kpeter@709: /// and \c POST_HEAP otherwise.
kpeter@709: /// In the latter case it is possible that the item will get back
kpeter@709: /// to the heap again.
deba@681: /// \param i The item.
deba@681: State state(const Item &i) const {
deba@683: int idx = _iim[i];
deba@681: if (idx >= 0) idx = 0;
deba@681: return State(idx);
deba@681: }
deba@681:
kpeter@709: /// \brief Set the state of an item in the heap.
deba@681: ///
kpeter@709: /// This function sets the state of the given item in the heap.
kpeter@709: /// It can be used to manually clear the heap when it is important
kpeter@709: /// to achive better time complexity.
deba@681: /// \param i The item.
deba@681: /// \param st The state. It should not be \c IN_HEAP.
deba@681: void state(const Item& i, State st) {
deba@681: switch (st) {
deba@681: case POST_HEAP:
deba@681: case PRE_HEAP:
deba@681: if (state(i) == IN_HEAP) {
deba@681: erase(i);
deba@681: }
deba@683: _iim[i] = st;
deba@681: break;
deba@681: case IN_HEAP:
deba@681: break;
deba@681: }
deba@681: }
deba@681:
deba@681: private:
deba@681:
deba@681: struct BucketItem {
deba@681: BucketItem(const Item& _item, int _value)
deba@681: : item(_item), value(_value) {}
deba@681:
deba@681: Item item;
deba@681: int value;
deba@681:
deba@681: int prev, next;
deba@681: };
deba@681:
deba@683: ItemIntMap& _iim;
deba@683: std::vector<int> _first;
deba@683: std::vector<BucketItem> _data;
deba@683: mutable int _minimum;
deba@681:
deba@681: }; // class BucketHeap
deba@681:
kpeter@710: /// \ingroup heaps
deba@681: ///
kpeter@709: /// \brief Simplified bucket heap data structure.
deba@681: ///
deba@681: /// This class implements a simplified \e bucket \e heap data
kpeter@709: /// structure. It does not provide some functionality, but it is
kpeter@709: /// faster and simpler than BucketHeap. The main difference is
kpeter@709: /// that BucketHeap stores a doubly-linked list for each key while
kpeter@709: /// this class stores only simply-linked lists. It supports erasing
kpeter@709: /// only for the item having minimum priority and it does not support
kpeter@709: /// key increasing and decreasing.
deba@681: ///
kpeter@709: /// Note that this implementation does not conform to the
kpeter@709: /// \ref concepts::Heap "heap concept" due to the lack of some
kpeter@709: /// functionality.
kpeter@709: ///
kpeter@709: /// \tparam IM A read-writable item map with \c int values, used
kpeter@709: /// internally to handle the cross references.
kpeter@709: /// \tparam MIN Indicate if the heap is a \e min-heap or a \e max-heap.
kpeter@709: /// The default is \e min-heap. If this parameter is set to \c false,
kpeter@709: /// then the comparison is reversed, so the top(), prio() and pop()
kpeter@709: /// functions deal with the item having maximum priority instead of the
kpeter@709: /// minimum.
deba@681: ///
deba@681: /// \sa BucketHeap
deba@683: template <typename IM, bool MIN = true >
deba@681: class SimpleBucketHeap {
deba@681:
deba@681: public:
kpeter@709:
kpeter@709: /// Type of the item-int map.
kpeter@709: typedef IM ItemIntMap;
kpeter@709: /// Type of the priorities.
deba@681: typedef int Prio;
kpeter@709: /// Type of the items stored in the heap.
kpeter@709: typedef typename ItemIntMap::Key Item;
kpeter@709: /// Type of the item-priority pairs.
kpeter@709: typedef std::pair<Item,Prio> Pair;
deba@681:
deba@682: private:
deba@682:
deba@683: typedef _bucket_heap_bits::DirectionTraits<MIN> Direction;
deba@682:
deba@682: public:
deba@682:
kpeter@709: /// \brief Type to represent the states of the items.
deba@681: ///
kpeter@709: /// Each item has a state associated to it. It can be "in heap",
kpeter@709: /// "pre-heap" or "post-heap". The latter two are indifferent from the
deba@681: /// heap's point of view, but may be useful to the user.
deba@681: ///
deba@683: /// The item-int map must be initialized in such way that it assigns
deba@683: /// \c PRE_HEAP (<tt>-1</tt>) to any element to be put in the heap.
deba@681: enum State {
deba@683: IN_HEAP = 0, ///< = 0.
deba@683: PRE_HEAP = -1, ///< = -1.
deba@683: POST_HEAP = -2 ///< = -2.
deba@681: };
deba@681:
deba@681: public:
deba@681:
kpeter@709: /// \brief Constructor.
deba@681: ///
kpeter@709: /// Constructor.
kpeter@709: /// \param map A map that assigns \c int values to the items.
kpeter@709: /// It is used internally to handle the cross references.
kpeter@709: /// The assigned value must be \c PRE_HEAP (<tt>-1</tt>) for each item.
deba@683: explicit SimpleBucketHeap(ItemIntMap &map)
deba@683: : _iim(map), _free(-1), _num(0), _minimum(0) {}
deba@681:
kpeter@709: /// \brief The number of items stored in the heap.
deba@681: ///
kpeter@709: /// This function returns the number of items stored in the heap.
deba@683: int size() const { return _num; }
deba@681:
kpeter@709: /// \brief Check if the heap is empty.
deba@681: ///
kpeter@709: /// This function returns \c true if the heap is empty.
deba@683: bool empty() const { return _num == 0; }
deba@681:
kpeter@709: /// \brief Make the heap empty.
deba@681: ///
kpeter@709: /// This functon makes the heap empty.
kpeter@709: /// It does not change the cross reference map. If you want to reuse
kpeter@709: /// a heap that is not surely empty, you should first clear it and
kpeter@709: /// then you should set the cross reference map to \c PRE_HEAP
kpeter@709: /// for each item.
deba@681: void clear() {
deba@683: _data.clear(); _first.clear(); _free = -1; _num = 0; _minimum = 0;
deba@681: }
deba@681:
deba@681: /// \brief Insert a pair of item and priority into the heap.
deba@681: ///
kpeter@709: /// This function inserts \c p.first to the heap with priority
kpeter@709: /// \c p.second.
deba@681: /// \param p The pair to insert.
kpeter@709: /// \pre \c p.first must not be stored in the heap.
deba@681: void push(const Pair& p) {
deba@681: push(p.first, p.second);
deba@681: }
deba@681:
deba@681: /// \brief Insert an item into the heap with the given priority.
deba@681: ///
kpeter@709: /// This function inserts the given item into the heap with the
kpeter@709: /// given priority.
deba@681: /// \param i The item to insert.
deba@681: /// \param p The priority of the item.
kpeter@709: /// \pre \e i must not be stored in the heap.
deba@681: void push(const Item &i, const Prio &p) {
deba@681: int idx;
deba@683: if (_free == -1) {
deba@683: idx = _data.size();
deba@683: _data.push_back(BucketItem(i));
deba@681: } else {
deba@683: idx = _free;
deba@683: _free = _data[idx].next;
deba@683: _data[idx].item = i;
deba@681: }
deba@683: _iim[i] = idx;
deba@683: if (p >= int(_first.size())) _first.resize(p + 1, -1);
deba@683: _data[idx].next = _first[p];
deba@683: _first[p] = idx;
deba@683: if (Direction::less(p, _minimum)) {
deba@683: _minimum = p;
deba@681: }
deba@683: ++_num;
deba@681: }
deba@681:
kpeter@709: /// \brief Return the item having minimum priority.
deba@681: ///
kpeter@709: /// This function returns the item having minimum priority.
kpeter@709: /// \pre The heap must be non-empty.
deba@681: Item top() const {
deba@683: while (_first[_minimum] == -1) {
deba@683: Direction::increase(_minimum);
deba@681: }
deba@683: return _data[_first[_minimum]].item;
deba@681: }
deba@681:
kpeter@709: /// \brief The minimum priority.
deba@681: ///
kpeter@709: /// This function returns the minimum priority.
kpeter@709: /// \pre The heap must be non-empty.
deba@681: Prio prio() const {
deba@683: while (_first[_minimum] == -1) {
deba@683: Direction::increase(_minimum);
deba@681: }
deba@683: return _minimum;
deba@681: }
deba@681:
kpeter@709: /// \brief Remove the item having minimum priority.
deba@681: ///
kpeter@709: /// This function removes the item having minimum priority.
deba@681: /// \pre The heap must be non-empty.
deba@681: void pop() {
deba@683: while (_first[_minimum] == -1) {
deba@683: Direction::increase(_minimum);
deba@681: }
deba@683: int idx = _first[_minimum];
deba@683: _iim[_data[idx].item] = -2;
deba@683: _first[_minimum] = _data[idx].next;
deba@683: _data[idx].next = _free;
deba@683: _free = idx;
deba@683: --_num;
deba@681: }
deba@681:
kpeter@709: /// \brief The priority of the given item.
deba@681: ///
kpeter@709: /// This function returns the priority of the given item.
deba@681: /// \param i The item.
kpeter@709: /// \pre \e i must be in the heap.
kpeter@709: /// \warning This operator is not a constant time function because
kpeter@709: /// it scans the whole data structure to find the proper value.
deba@681: Prio operator[](const Item &i) const {
kpeter@709: for (int k = 0; k < int(_first.size()); ++k) {
deba@683: int idx = _first[k];
deba@681: while (idx != -1) {
deba@683: if (_data[idx].item == i) {
deba@681: return k;
deba@681: }
deba@683: idx = _data[idx].next;
deba@681: }
deba@681: }
deba@681: return -1;
deba@681: }
deba@681:
kpeter@709: /// \brief Return the state of an item.
deba@681: ///
kpeter@709: /// This method returns \c PRE_HEAP if the given item has never
kpeter@709: /// been in the heap, \c IN_HEAP if it is in the heap at the moment,
kpeter@709: /// and \c POST_HEAP otherwise.
kpeter@709: /// In the latter case it is possible that the item will get back
kpeter@709: /// to the heap again.
deba@681: /// \param i The item.
deba@681: State state(const Item &i) const {
deba@683: int idx = _iim[i];
deba@681: if (idx >= 0) idx = 0;
deba@681: return State(idx);
deba@681: }
deba@681:
deba@681: private:
deba@681:
deba@681: struct BucketItem {
deba@681: BucketItem(const Item& _item)
deba@681: : item(_item) {}
deba@681:
deba@681: Item item;
deba@681: int next;
deba@681: };
deba@681:
deba@683: ItemIntMap& _iim;
deba@683: std::vector<int> _first;
deba@683: std::vector<BucketItem> _data;
deba@683: int _free, _num;
deba@683: mutable int _minimum;
deba@681:
deba@681: }; // class SimpleBucketHeap
deba@681:
deba@681: }
deba@681:
deba@681: #endif