Location: LEMON/LEMON-official/lemon/concepts/heap.h

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kpeter (Peter Kovacs)
Entirely rework CapacityScaling (#180) - Use the new interface similarly to NetworkSimplex. - Rework the implementation using an efficient internal structure for handling the residual network. This improvement made the code much faster (up to 2-5 times faster on large graphs). - Handle GEQ supply type (LEQ is not supported). - Handle negative costs for arcs of finite capacity. (Note that this algorithm cannot handle arcs of negative cost and infinite upper bound, thus it returns UNBOUNDED if such an arc exists.) - Extend the documentation.
/* -*- 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_CONCEPTS_HEAP_H
#define LEMON_CONCEPTS_HEAP_H
///\ingroup concept
///\file
///\brief The concept of heaps.
#include <lemon/core.h>
#include <lemon/concept_check.h>
namespace lemon {
namespace concepts {
/// \addtogroup concept
/// @{
/// \brief The heap concept.
///
/// This concept class describes the main interface of heaps.
/// The various \ref heaps "heap structures" are efficient
/// implementations of the abstract data type \e priority \e queue.
/// They store items with specified values called \e priorities
/// in such a way that finding and removing the item with minimum
/// priority are efficient. The basic operations are adding and
/// erasing items, changing the priority of an item, etc.
///
/// Heaps are crucial in several algorithms, such as Dijkstra and Prim.
/// Any class that conforms to this concept can be used easily in such
/// algorithms.
///
/// \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>.
#ifdef DOXYGEN
template <typename PR, typename IM, typename CMP>
#else
template <typename PR, typename IM, typename CMP = std::less<PR> >
#endif
class Heap {
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;
/// \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. The "in heap" state constant.
PRE_HEAP = -1, ///< = -1. The "pre-heap" state constant.
POST_HEAP = -2 ///< = -2. The "post-heap" state constant.
};
/// \brief Constructor.
///
/// Constructor.
/// \param map A map that assigns \c int values to keys of type
/// \c Item. It is used internally by the heap implementations to
/// handle the cross references. The assigned value must be
/// \c PRE_HEAP (<tt>-1</tt>) for each item.
explicit Heap(ItemIntMap &map) {}
/// \brief Constructor.
///
/// Constructor.
/// \param map A map that assigns \c int values to keys of type
/// \c Item. It is used internally by the heap implementations 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.
explicit Heap(ItemIntMap &map, const CMP &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 0; }
/// \brief Check if the heap is empty.
///
/// This function returns \c true if the heap is empty.
bool empty() const { return false; }
/// \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() {}
/// \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) {}
/// \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 {}
/// \brief The minimum priority.
///
/// This function returns the minimum priority.
/// \pre The heap must be non-empty.
Prio prio() const {}
/// \brief Remove the item having minimum priority.
///
/// This function removes the item having minimum priority.
/// \pre The heap must be non-empty.
void pop() {}
/// \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) {}
/// \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 {}
/// \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) {}
/// \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) {}
/// \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) {}
/// \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 {}
/// \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) {}
template <typename _Heap>
struct Constraints {
public:
void constraints() {
typedef typename _Heap::Item OwnItem;
typedef typename _Heap::Prio OwnPrio;
typedef typename _Heap::State OwnState;
Item item;
Prio prio;
item=Item();
prio=Prio();
ignore_unused_variable_warning(item);
ignore_unused_variable_warning(prio);
OwnItem own_item;
OwnPrio own_prio;
OwnState own_state;
own_item=Item();
own_prio=Prio();
ignore_unused_variable_warning(own_item);
ignore_unused_variable_warning(own_prio);
ignore_unused_variable_warning(own_state);
_Heap heap1(map);
_Heap heap2 = heap1;
ignore_unused_variable_warning(heap1);
ignore_unused_variable_warning(heap2);
int s = heap.size();
ignore_unused_variable_warning(s);
bool e = heap.empty();
ignore_unused_variable_warning(e);
prio = heap.prio();
item = heap.top();
prio = heap[item];
own_prio = heap.prio();
own_item = heap.top();
own_prio = heap[own_item];
heap.push(item, prio);
heap.push(own_item, own_prio);
heap.pop();
heap.set(item, prio);
heap.decrease(item, prio);
heap.increase(item, prio);
heap.set(own_item, own_prio);
heap.decrease(own_item, own_prio);
heap.increase(own_item, own_prio);
heap.erase(item);
heap.erase(own_item);
heap.clear();
own_state = heap.state(own_item);
heap.state(own_item, own_state);
own_state = _Heap::PRE_HEAP;
own_state = _Heap::IN_HEAP;
own_state = _Heap::POST_HEAP;
}
_Heap& heap;
ItemIntMap& map;
};
};
/// @}
} // namespace lemon
}
#endif