alpar@906: /* -*- C++ -*-
klao@39: *
alpar@1956: * This file is a part of LEMON, a generic C++ optimization library
alpar@1956: *
alpar@1956: * Copyright (C) 2003-2006
alpar@1956: * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
alpar@1359: * (Egervary Research Group on Combinatorial Optimization, EGRES).
klao@39: *
alpar@906: * Permission to use, modify and distribute this software is granted
alpar@906: * provided that this copyright notice appears in all copies. For
alpar@906: * precise terms see the accompanying LICENSE file.
klao@39: *
alpar@906: * This software is provided "AS IS" with no warranty of any kind,
alpar@906: * express or implied, and with no claim as to its suitability for any
alpar@906: * purpose.
klao@39: *
klao@39: */
klao@39:
alpar@921: #ifndef LEMON_BIN_HEAP_H
alpar@921: #define LEMON_BIN_HEAP_H
klao@37:
klao@491: ///\ingroup auxdat
klao@274: ///\file
klao@274: ///\brief Binary Heap implementation.
klao@274:
klao@37: #include <vector>
klao@37: #include <utility>
klao@37: #include <functional>
klao@37:
alpar@921: namespace lemon {
klao@37:
deba@1834: /// \ingroup auxdat
alpar@430:
jacint@1270: /// A Binary Heap implementation.
alpar@967:
jacint@1270: ///This class implements the \e binary \e heap data structure. A \e heap
jacint@1270: ///is a data structure for storing items with specified values called \e
jacint@1270: ///priorities in such a way that finding the item with minimum priority is
jacint@1270: ///efficient. \c Compare specifies the ordering of the priorities. In a heap
jacint@1270: ///one can change the priority of an item, add or erase an item, etc.
jacint@1270: ///
jacint@1270: ///\param Item Type of the items to be stored.
jacint@1270: ///\param Prio Type of the priority of the items.
jacint@1270: ///\param ItemIntMap A read and writable Item int map, used internally
jacint@1270: ///to handle the cross references.
jacint@1270: ///\param Compare A class for the ordering of the priorities. The
jacint@1270: ///default is \c std::less<Prio>.
alpar@967: ///
alpar@967: ///\sa FibHeap
alpar@967: ///\sa Dijkstra
klao@172: template <typename Item, typename Prio, typename ItemIntMap,
klao@172: typename Compare = std::less<Prio> >
klao@37: class BinHeap {
klao@37:
klao@37: public:
klao@172: typedef Item ItemType;
klao@37: // FIXME: stl-ben nem ezt hivjak value_type -nak, hanem a kovetkezot...
klao@172: typedef Prio PrioType;
klao@172: typedef std::pair<ItemType,PrioType> PairType;
klao@172: typedef ItemIntMap ItemIntMapType;
klao@172: typedef Compare PrioCompare;
klao@37:
deba@1331: /// \brief Type to represent the items states.
klao@274: ///
deba@1331: /// Each Item element have a state associated to it. It may be "in heap",
alpar@1336: /// "pre heap" or "post heap". The latter two are indifferent from the
deba@1331: /// heap's point of view, but may be useful to the user.
deba@1331: ///
alpar@1336: /// The ItemIntMap \e should be initialized in such way that it maps
deba@1331: /// PRE_HEAP (-1) to any element to be put in the heap...
klao@39: enum state_enum {
klao@37: IN_HEAP = 0,
klao@37: PRE_HEAP = -1,
klao@37: POST_HEAP = -2
klao@37: };
klao@37:
klao@37: private:
klao@37: std::vector<PairType> data;
klao@37: Compare comp;
klao@172: ItemIntMap &iim;
klao@37:
klao@37: public:
deba@1331: /// \brief The constructor.
deba@1331: ///
deba@1331: /// The constructor.
deba@1331: /// \param _iim should be given to the constructor, since it is used
deba@1331: /// internally to handle the cross references. The value of the map
deba@1331: /// should be PRE_HEAP (-1) for each element.
deba@1185: explicit BinHeap(ItemIntMap &_iim) : iim(_iim) {}
jacint@1270:
deba@1331: /// \brief The constructor.
deba@1331: ///
deba@1331: /// The constructor.
deba@1331: /// \param _iim should be given to the constructor, since it is used
deba@1331: /// internally to handle the cross references. The value of the map
deba@1331: /// should be PRE_HEAP (-1) for each element.
deba@1331: ///
deba@1331: /// \param _comp The comparator function object.
deba@1191: BinHeap(ItemIntMap &_iim, const Compare &_comp)
deba@1185: : iim(_iim), comp(_comp) {}
klao@37:
klao@37:
deba@1331: /// The number of items stored in the heap.
deba@1331: ///
deba@1331: /// \brief Returns the number of items stored in the heap.
klao@37: int size() const { return data.size(); }
jacint@1270:
deba@1331: /// \brief Checks if the heap stores no items.
deba@1331: ///
deba@1331: /// Returns \c true if and only if the heap stores no items.
klao@41: bool empty() const { return data.empty(); }
klao@37:
deba@1717: /// \brief Make empty this heap.
deba@1717: ///
deba@2050: /// Make empty this heap. It does not change the cross reference map.
deba@2050: /// If you want to reuse what is not surely empty you should first clear
deba@2050: /// the heap and after that you should set the cross reference map for
deba@2050: /// each item to \c PRE_HEAP.
deba@1717: void clear() {
deba@1717: data.clear();
deba@1717: }
deba@1717:
klao@37: private:
klao@37: static int parent(int i) { return (i-1)/2; }
klao@37: static int second_child(int i) { return 2*i+2; }
klao@214: bool less(const PairType &p1, const PairType &p2) const {
klao@37: return comp(p1.second, p2.second);
klao@37: }
klao@37:
klao@37: int bubble_up(int hole, PairType p);
klao@37: int bubble_down(int hole, PairType p, int length);
klao@37:
klao@37: void move(const PairType &p, int i) {
klao@37: data[i] = p;
klao@172: iim.set(p.first, i);
klao@37: }
klao@37:
klao@41: void rmidx(int h) {
klao@41: int n = data.size()-1;
klao@41: if( h>=0 && h<=n ) {
klao@172: iim.set(data[h].first, POST_HEAP);
klao@41: if ( h<n ) {
klao@41: bubble_down(h, data[n], n);
klao@41: }
klao@41: data.pop_back();
klao@41: }
klao@41: }
klao@41:
klao@37: public:
deba@1331: /// \brief Insert a pair of item and priority into the heap.
deba@1331: ///
deba@1331: /// Adds \c p.first to the heap with priority \c p.second.
deba@1331: /// \param p The pair to insert.
klao@37: void push(const PairType &p) {
klao@37: int n = data.size();
klao@37: data.resize(n+1);
klao@37: bubble_up(n, p);
klao@37: }
jacint@1270:
deba@1331: /// \brief Insert an item into the heap with the given heap.
deba@1331: ///
deba@1331: /// Adds \c i to the heap with priority \c p.
deba@1331: /// \param i The item to insert.
deba@1331: /// \param p The priority of the item.
klao@172: void push(const Item &i, const Prio &p) { push(PairType(i,p)); }
klao@37:
deba@1331: /// \brief Returns the item with minimum priority relative to \c Compare.
deba@1331: ///
deba@1331: /// This method returns the item with minimum priority relative to \c
deba@1331: /// Compare.
deba@1331: /// \pre The heap must be nonempty.
klao@172: Item top() const {
klao@37: return data[0].first;
klao@37: }
jacint@1270:
deba@1331: /// \brief Returns the minimum priority relative to \c Compare.
deba@1331: ///
deba@1331: /// It returns the minimum priority relative to \c Compare.
deba@1331: /// \pre The heap must be nonempty.
klao@274: Prio prio() const {
klao@37: return data[0].second;
klao@37: }
klao@37:
deba@1331: /// \brief Deletes the item with minimum priority relative to \c Compare.
deba@1331: ///
deba@1331: /// This method deletes the item with minimum priority relative to \c
deba@1331: /// Compare from the heap.
deba@1331: /// \pre The heap must be non-empty.
klao@37: void pop() {
klao@41: rmidx(0);
klao@41: }
klao@41:
deba@1331: /// \brief Deletes \c i from the heap.
deba@1331: ///
deba@1331: /// This method deletes item \c i from the heap, if \c i was
deba@1331: /// already stored in the heap.
deba@1331: /// \param i The item to erase.
klao@172: void erase(const Item &i) {
jacint@221: rmidx(iim[i]);
klao@37: }
klao@37:
jacint@1270:
deba@1331: /// \brief Returns the priority of \c i.
deba@1331: ///
deba@1331: /// This function returns the priority of item \c i.
deba@1331: /// \pre \c i must be in the heap.
deba@1331: /// \param i The item.
klao@274: Prio operator[](const Item &i) const {
jacint@221: int idx = iim[i];
klao@37: return data[idx].second;
klao@37: }
klao@274:
deba@1331: /// \brief \c i gets to the heap with priority \c p independently
deba@1331: /// if \c i was already there.
deba@1331: ///
deba@1331: /// This method calls \ref push(\c i, \c p) if \c i is not stored
deba@1331: /// in the heap and sets the priority of \c i to \c p otherwise.
deba@1331: /// \param i The item.
deba@1331: /// \param p The priority.
klao@172: void set(const Item &i, const Prio &p) {
jacint@221: int idx = iim[i];
klao@37: if( idx < 0 ) {
klao@172: push(i,p);
klao@37: }
klao@172: else if( comp(p, data[idx].second) ) {
klao@172: bubble_up(idx, PairType(i,p));
klao@37: }
klao@37: else {
klao@172: bubble_down(idx, PairType(i,p), data.size());
klao@37: }
klao@37: }
klao@37:
deba@1331: /// \brief Decreases the priority of \c i to \c p.
jacint@1270:
deba@1331: /// This method decreases the priority of item \c i to \c p.
deba@1331: /// \pre \c i must be stored in the heap with priority at least \c
deba@1331: /// p relative to \c Compare.
deba@1331: /// \param i The item.
deba@1331: /// \param p The priority.
klao@172: void decrease(const Item &i, const Prio &p) {
jacint@221: int idx = iim[i];
klao@172: bubble_up(idx, PairType(i,p));
klao@37: }
jacint@1270:
deba@1331: /// \brief Increases the priority of \c i to \c p.
deba@1331: ///
deba@1331: /// This method sets the priority of item \c i to \c p.
deba@1331: /// \pre \c i must be stored in the heap with priority at most \c
deba@1331: /// p relative to \c Compare.
deba@1331: /// \param i The item.
deba@1331: /// \param p The priority.
klao@172: void increase(const Item &i, const Prio &p) {
jacint@221: int idx = iim[i];
klao@172: bubble_down(idx, PairType(i,p), data.size());
klao@37: }
klao@37:
deba@1331: /// \brief Returns if \c item is in, has already been in, or has
deba@1331: /// never been in the heap.
deba@1331: ///
deba@1331: /// This method returns PRE_HEAP if \c item has never been in the
deba@1331: /// heap, IN_HEAP if it is in the heap at the moment, and POST_HEAP
deba@1331: /// otherwise. In the latter case it is possible that \c item will
deba@1331: /// get back to the heap again.
deba@1331: /// \param i The item.
klao@172: state_enum state(const Item &i) const {
jacint@221: int s = iim[i];
klao@39: if( s>=0 )
klao@39: s=0;
klao@39: return state_enum(s);
klao@39: }
klao@39:
deba@1902: /// \brief Sets the state of the \c item in the heap.
deba@1902: ///
deba@1902: /// Sets the state of the \c item in the heap. It can be used to
deba@1902: /// manually clear the heap when it is important to achive the
deba@1902: /// better time complexity.
deba@1902: /// \param i The item.
deba@1902: /// \param st The state. It should not be \c IN_HEAP.
deba@1902: void state(const Item& i, state_enum st) {
deba@1902: switch (st) {
deba@1902: case POST_HEAP:
deba@1902: case PRE_HEAP:
deba@1902: if (state(i) == IN_HEAP) {
deba@1902: erase(i);
deba@1902: }
deba@1903: iim[i] = st;
deba@1902: break;
deba@1906: case IN_HEAP:
deba@1906: break;
deba@1902: }
deba@1902: }
deba@1902:
klao@37: }; // class BinHeap
klao@37:
klao@37:
klao@37: template <typename K, typename V, typename M, typename C>
klao@37: int BinHeap<K,V,M,C>::bubble_up(int hole, PairType p) {
klao@37: int par = parent(hole);
klao@37: while( hole>0 && less(p,data[par]) ) {
klao@37: move(data[par],hole);
klao@37: hole = par;
klao@37: par = parent(hole);
klao@37: }
klao@37: move(p, hole);
klao@37: return hole;
klao@37: }
klao@37:
klao@37: template <typename K, typename V, typename M, typename C>
klao@37: int BinHeap<K,V,M,C>::bubble_down(int hole, PairType p, int length) {
klao@37: int child = second_child(hole);
klao@37: while(child < length) {
klao@37: if( less(data[child-1], data[child]) ) {
klao@37: --child;
klao@37: }
klao@37: if( !less(data[child], p) )
klao@37: goto ok;
klao@37: move(data[child], hole);
klao@37: hole = child;
klao@37: child = second_child(hole);
klao@37: }
klao@37: child--;
klao@37: if( child<length && less(data[child], p) ) {
klao@37: move(data[child], hole);
klao@37: hole=child;
klao@37: }
klao@37: ok:
klao@37: move(p, hole);
klao@37: return hole;
klao@37: }
klao@37:
alpar@430:
alpar@921: } // namespace lemon
klao@37:
alpar@921: #endif // LEMON_BIN_HEAP_H