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extern/quadriflow/3rd/lemon-1.3.1/lemon/quad_heap.h

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/* -*- 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_QUAD_HEAP_H
#define LEMON_QUAD_HEAP_H
///\ingroup heaps
///\file
///\brief Fourary (quaternary) heap implementation.
#include <vector>
#include <utility>
#include <functional>
namespace lemon {
/// \ingroup heaps
///
///\brief Fourary (quaternary) heap data structure.
///
/// This class implements the \e Fourary (\e quaternary) \e heap
/// data structure.
/// It fully conforms to the \ref concepts::Heap "heap concept".
///
/// The fourary heap is a specialization of the \ref DHeap "D-ary heap"
/// for <tt>D=4</tt>. It is similar to the \ref BinHeap "binary heap",
/// but its nodes have at most four children, instead of two.
///
/// \tparam PR Type of the priorities of the items.
/// \tparam IM A read-writable item map with \c int values, used
/// internally to handle the cross references.
/// \tparam CMP A functor class for comparing the priorities.
/// The default is \c std::less<PR>.
///
///\sa BinHeap
///\sa DHeap
#ifdef DOXYGEN
template <typename PR, typename IM, typename CMP>
#else
template <typename PR, typename IM, typename CMP = std::less<PR> >
#endif
class QuadHeap {
public:
/// Type of the item-int map.
typedef IM ItemIntMap;
/// Type of the priorities.
typedef PR Prio;
/// Type of the items stored in the heap.
typedef typename ItemIntMap::Key Item;
/// Type of the item-priority pairs.
typedef std::pair<Item,Prio> Pair;
/// Functor type for comparing the priorities.
typedef CMP Compare;
/// \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:
std::vector<Pair> _data;
Compare _comp;
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.
explicit QuadHeap(ItemIntMap &map) : _iim(map) {}
/// \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 comp The function object used for comparing the priorities.
QuadHeap(ItemIntMap &map, const Compare &comp)
: _iim(map), _comp(comp) {}
/// \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.
void clear() { _data.clear(); }
private:
static int parent(int i) { return (i-1)/4; }
static int firstChild(int i) { return 4*i+1; }
bool less(const Pair &p1, const Pair &p2) const {
return _comp(p1.second, p2.second);
}
void bubbleUp(int hole, Pair p) {
int par = parent(hole);
while( hole>0 && less(p,_data[par]) ) {
move(_data[par],hole);
hole = par;
par = parent(hole);
}
move(p, hole);
}
void bubbleDown(int hole, Pair p, int length) {
if( length>1 ) {
int child = firstChild(hole);
while( child+3<length ) {
int min=child;
if( less(_data[++child], _data[min]) ) min=child;
if( less(_data[++child], _data[min]) ) min=child;
if( less(_data[++child], _data[min]) ) min=child;
if( !less(_data[min], p) )
goto ok;
move(_data[min], hole);
hole = min;
child = firstChild(hole);
}
if ( child<length ) {
int min = child;
if( ++child<length && less(_data[child], _data[min]) ) min=child;
if( ++child<length && less(_data[child], _data[min]) ) min=child;
if( less(_data[min], p) ) {
move(_data[min], hole);
hole = min;
}
}
}
ok:
move(p, hole);
}
void move(const Pair &p, int i) {
_data[i] = p;
_iim.set(p.first, i);
}
public:
/// \brief Insert a pair of item and priority into the heap.
///
/// This function inserts \c p.first to the heap with priority
/// \c p.second.
/// \param p The pair to insert.
/// \pre \c p.first must not be stored in the heap.
void push(const Pair &p) {
int n = _data.size();
_data.resize(n+1);
bubbleUp(n, p);
}
/// \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.
void push(const Item &i, const Prio &p) { push(Pair(i,p)); }
/// \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 { return _data[0].first; }
/// \brief The minimum priority.
///
/// This function returns the minimum priority.
/// \pre The heap must be non-empty.
Prio prio() const { return _data[0].second; }
/// \brief Remove the item having minimum priority.
///
/// This function removes the item having minimum priority.
/// \pre The heap must be non-empty.
void pop() {
int n = _data.size()-1;
_iim.set(_data[0].first, POST_HEAP);
if (n>0) bubbleDown(0, _data[n], n);
_data.pop_back();
}
/// \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 h = _iim[i];
int n = _data.size()-1;
_iim.set(_data[h].first, POST_HEAP);
if( h<n ) {
if( less(_data[parent(h)], _data[n]) )
bubbleDown(h, _data[n], n);
else
bubbleUp(h, _data[n]);
}
_data.pop_back();
}
/// \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].second;
}
/// \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.
void set(const Item &i, const Prio &p) {
int idx = _iim[i];
if( idx < 0 )
push(i,p);
else if( _comp(p, _data[idx].second) )
bubbleUp(idx, Pair(i,p));
else
bubbleDown(idx, Pair(i,p), _data.size());
}
/// \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.
void decrease(const Item &i, const Prio &p) {
int idx = _iim[i];
bubbleUp(idx, Pair(i,p));
}
/// \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];
bubbleDown(idx, Pair(i,p), _data.size());
}
/// \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;
}
}
/// \brief Replace an item in the heap.
///
/// This function replaces item \c i with item \c j.
/// Item \c i must be in the heap, while \c j must be out of the heap.
/// After calling this method, item \c i will be out of the
/// heap and \c j will be in the heap with the same prioriority
/// as item \c i had before.
void replace(const Item& i, const Item& j) {
int idx = _iim[i];
_iim.set(i, _iim[j]);
_iim.set(j, idx);
_data[idx].first = j;
}
}; // class QuadHeap
} // namespace lemon
#endif // LEMON_FOURARY_HEAP_H