/* -*- 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_KARY_HEAP_H
#define LEMON_KARY_HEAP_H
///\ingroup heaps
///\file
///\brief Fourary heap implementation.
#include
#include
#include
namespace lemon {
/// \ingroup heaps
///
///\brief K-ary heap data structure.
///
/// This class implements the \e K-ary \e heap data structure.
/// It fully conforms to the \ref concepts::Heap "heap concept".
///
/// The \ref KaryHeap "K-ary heap" is a generalization of the
/// \ref BinHeap "binary heap" structure, its nodes have at most
/// \c K children, instead of two.
/// \ref BinHeap and \ref FouraryHeap are specialized implementations
/// of this structure for `K=2` and `K=4`, respectively.
///
/// \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 K The degree of the heap, each node have at most \e K
/// children. The default is 16. Powers of two are suggested to use
/// so that the multiplications and divisions needed to traverse the
/// nodes of the heap could be performed faster.
/// \tparam CMP A functor class for comparing the priorities.
/// The default is \c std::less.
///
///\sa BinHeap
///\sa FouraryHeap
#ifdef DOXYGEN
template
#else
template >
#endif
class KaryHeap {
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- 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 (
`-1`) 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 _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 (`-1`) for each item.
explicit KaryHeap(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 (`-1`) for each item.
/// \param comp The function object used for comparing the priorities.
KaryHeap(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:
int parent(int i) { return (i-1)/K; }
int firstChild(int i) { return K*i+1; }
bool less(const Pair &p1, const Pair &p2) const {
return _comp(p1.second, p2.second);
}
int findMin(const int child, const int length) {
int min=child, i=1;
while( i0 && 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( child0) 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=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 KaryHeap
} // namespace lemon
#endif // LEMON_KARY_HEAP_H