lemon/concepts/heap.h
author Alpar Juttner <alpar@cs.elte.hu>
Wed, 07 Aug 2013 06:55:05 +0200
changeset 983 8b2d4e5d96e4
parent 954 be7dd3a8d6a3
parent 982 3e711ee55d31
permissions -rw-r--r--
Merge #294 to branches >=1.2
     1 /* -*- mode: C++; indent-tabs-mode: nil; -*-
     2  *
     3  * This file is a part of LEMON, a generic C++ optimization library.
     4  *
     5  * Copyright (C) 2003-2010
     6  * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
     7  * (Egervary Research Group on Combinatorial Optimization, EGRES).
     8  *
     9  * Permission to use, modify and distribute this software is granted
    10  * provided that this copyright notice appears in all copies. For
    11  * precise terms see the accompanying LICENSE file.
    12  *
    13  * This software is provided "AS IS" with no warranty of any kind,
    14  * express or implied, and with no claim as to its suitability for any
    15  * purpose.
    16  *
    17  */
    18 
    19 #ifndef LEMON_CONCEPTS_HEAP_H
    20 #define LEMON_CONCEPTS_HEAP_H
    21 
    22 ///\ingroup concept
    23 ///\file
    24 ///\brief The concept of heaps.
    25 
    26 #include <lemon/core.h>
    27 #include <lemon/concept_check.h>
    28 
    29 namespace lemon {
    30 
    31   namespace concepts {
    32 
    33     /// \addtogroup concept
    34     /// @{
    35 
    36     /// \brief The heap concept.
    37     ///
    38     /// This concept class describes the main interface of heaps.
    39     /// The various \ref heaps "heap structures" are efficient
    40     /// implementations of the abstract data type \e priority \e queue.
    41     /// They store items with specified values called \e priorities
    42     /// in such a way that finding and removing the item with minimum
    43     /// priority are efficient. The basic operations are adding and
    44     /// erasing items, changing the priority of an item, etc.
    45     ///
    46     /// Heaps are crucial in several algorithms, such as Dijkstra and Prim.
    47     /// Any class that conforms to this concept can be used easily in such
    48     /// algorithms.
    49     ///
    50     /// \tparam PR Type of the priorities of the items.
    51     /// \tparam IM A read-writable item map with \c int values, used
    52     /// internally to handle the cross references.
    53     /// \tparam CMP A functor class for comparing the priorities.
    54     /// The default is \c std::less<PR>.
    55 #ifdef DOXYGEN
    56     template <typename PR, typename IM, typename CMP>
    57 #else
    58     template <typename PR, typename IM, typename CMP = std::less<PR> >
    59 #endif
    60     class Heap {
    61     public:
    62 
    63       /// Type of the item-int map.
    64       typedef IM ItemIntMap;
    65       /// Type of the priorities.
    66       typedef PR Prio;
    67       /// Type of the items stored in the heap.
    68       typedef typename ItemIntMap::Key Item;
    69 
    70       /// \brief Type to represent the states of the items.
    71       ///
    72       /// Each item has a state associated to it. It can be "in heap",
    73       /// "pre-heap" or "post-heap". The latter two are indifferent from the
    74       /// heap's point of view, but may be useful to the user.
    75       ///
    76       /// The item-int map must be initialized in such way that it assigns
    77       /// \c PRE_HEAP (<tt>-1</tt>) to any element to be put in the heap.
    78       enum State {
    79         IN_HEAP = 0,    ///< = 0. The "in heap" state constant.
    80         PRE_HEAP = -1,  ///< = -1. The "pre-heap" state constant.
    81         POST_HEAP = -2  ///< = -2. The "post-heap" state constant.
    82       };
    83 
    84       /// \brief Constructor.
    85       ///
    86       /// Constructor.
    87       /// \param map A map that assigns \c int values to keys of type
    88       /// \c Item. It is used internally by the heap implementations to
    89       /// handle the cross references. The assigned value must be
    90       /// \c PRE_HEAP (<tt>-1</tt>) for each item.
    91 #ifdef DOXYGEN
    92       explicit Heap(ItemIntMap &map) {}
    93 #else
    94       explicit Heap(ItemIntMap&) {}
    95 #endif
    96 
    97       /// \brief Constructor.
    98       ///
    99       /// Constructor.
   100       /// \param map A map that assigns \c int values to keys of type
   101       /// \c Item. It is used internally by the heap implementations to
   102       /// handle the cross references. The assigned value must be
   103       /// \c PRE_HEAP (<tt>-1</tt>) for each item.
   104       /// \param comp The function object used for comparing the priorities.
   105 #ifdef DOXYGEN
   106       explicit Heap(ItemIntMap &map, const CMP &comp) {}
   107 #else
   108       explicit Heap(ItemIntMap&, const CMP&) {}
   109 #endif
   110 
   111       /// \brief The number of items stored in the heap.
   112       ///
   113       /// This function returns the number of items stored in the heap.
   114       int size() const { return 0; }
   115 
   116       /// \brief Check if the heap is empty.
   117       ///
   118       /// This function returns \c true if the heap is empty.
   119       bool empty() const { return false; }
   120 
   121       /// \brief Make the heap empty.
   122       ///
   123       /// This functon makes the heap empty.
   124       /// It does not change the cross reference map. If you want to reuse
   125       /// a heap that is not surely empty, you should first clear it and
   126       /// then you should set the cross reference map to \c PRE_HEAP
   127       /// for each item.
   128       void clear() {}
   129 
   130       /// \brief Insert an item into the heap with the given priority.
   131       ///
   132       /// This function inserts the given item into the heap with the
   133       /// given priority.
   134       /// \param i The item to insert.
   135       /// \param p The priority of the item.
   136       /// \pre \e i must not be stored in the heap.
   137 #ifdef DOXYGEN
   138       void push(const Item &i, const Prio &p) {}
   139 #else
   140       void push(const Item&, const Prio&) {}
   141 #endif
   142 
   143       /// \brief Return the item having minimum priority.
   144       ///
   145       /// This function returns the item having minimum priority.
   146       /// \pre The heap must be non-empty.
   147       Item top() const { return Item(); }
   148 
   149       /// \brief The minimum priority.
   150       ///
   151       /// This function returns the minimum priority.
   152       /// \pre The heap must be non-empty.
   153       Prio prio() const { return Prio(); }
   154 
   155       /// \brief Remove the item having minimum priority.
   156       ///
   157       /// This function removes the item having minimum priority.
   158       /// \pre The heap must be non-empty.
   159       void pop() {}
   160 
   161       /// \brief Remove the given item from the heap.
   162       ///
   163       /// This function removes the given item from the heap if it is
   164       /// already stored.
   165       /// \param i The item to delete.
   166       /// \pre \e i must be in the heap.
   167 #ifdef DOXYGEN
   168       void erase(const Item &i) {}
   169 #else
   170       void erase(const Item&) {}
   171 #endif
   172 
   173       /// \brief The priority of the given item.
   174       ///
   175       /// This function returns the priority of the given item.
   176       /// \param i The item.
   177       /// \pre \e i must be in the heap.
   178 #ifdef DOXYGEN
   179       Prio operator[](const Item &i) const {}
   180 #else
   181       Prio operator[](const Item&) const { return Prio(); }
   182 #endif
   183 
   184       /// \brief Set the priority of an item or insert it, if it is
   185       /// not stored in the heap.
   186       ///
   187       /// This method sets the priority of the given item if it is
   188       /// already stored in the heap. Otherwise it inserts the given
   189       /// item into the heap with the given priority.
   190       ///
   191       /// \param i The item.
   192       /// \param p The priority.
   193 #ifdef DOXYGEN
   194       void set(const Item &i, const Prio &p) {}
   195 #else
   196       void set(const Item&, const Prio&) {}
   197 #endif
   198 
   199       /// \brief Decrease the priority of an item to the given value.
   200       ///
   201       /// This function decreases the priority of an item to the given value.
   202       /// \param i The item.
   203       /// \param p The priority.
   204       /// \pre \e i must be stored in the heap with priority at least \e p.
   205 #ifdef DOXYGEN
   206       void decrease(const Item &i, const Prio &p) {}
   207 #else
   208       void decrease(const Item&, const Prio&) {}
   209 #endif
   210 
   211       /// \brief Increase the priority of an item to the given value.
   212       ///
   213       /// This function increases the priority of an item to the given value.
   214       /// \param i The item.
   215       /// \param p The priority.
   216       /// \pre \e i must be stored in the heap with priority at most \e p.
   217 #ifdef DOXYGEN
   218       void increase(const Item &i, const Prio &p) {}
   219 #else
   220       void increase(const Item&, const Prio&) {}
   221 #endif
   222 
   223       /// \brief Return the state of an item.
   224       ///
   225       /// This method returns \c PRE_HEAP if the given item has never
   226       /// been in the heap, \c IN_HEAP if it is in the heap at the moment,
   227       /// and \c POST_HEAP otherwise.
   228       /// In the latter case it is possible that the item will get back
   229       /// to the heap again.
   230       /// \param i The item.
   231 #ifdef DOXYGEN
   232       State state(const Item &i) const {}
   233 #else
   234       State state(const Item&) const { return PRE_HEAP; }
   235 #endif
   236 
   237       /// \brief Set the state of an item in the heap.
   238       ///
   239       /// This function sets the state of the given item in the heap.
   240       /// It can be used to manually clear the heap when it is important
   241       /// to achive better time complexity.
   242       /// \param i The item.
   243       /// \param st The state. It should not be \c IN_HEAP.
   244 #ifdef DOXYGEN
   245       void state(const Item& i, State st) {}
   246 #else
   247       void state(const Item&, State) {}
   248 #endif
   249 
   250 
   251       template <typename _Heap>
   252       struct Constraints {
   253       public:
   254         void constraints() {
   255           typedef typename _Heap::Item OwnItem;
   256           typedef typename _Heap::Prio OwnPrio;
   257           typedef typename _Heap::State OwnState;
   258 
   259           Item item;
   260           Prio prio;
   261           item=Item();
   262           prio=Prio();
   263           ::lemon::ignore_unused_variable_warning(item);
   264           ::lemon::ignore_unused_variable_warning(prio);
   265 
   266           OwnItem own_item;
   267           OwnPrio own_prio;
   268           OwnState own_state;
   269           own_item=Item();
   270           own_prio=Prio();
   271           ::lemon::ignore_unused_variable_warning(own_item);
   272           ::lemon::ignore_unused_variable_warning(own_prio);
   273           ::lemon::ignore_unused_variable_warning(own_state);
   274 
   275           _Heap heap1(map);
   276           _Heap heap2 = heap1;
   277           ::lemon::ignore_unused_variable_warning(heap1);
   278           ::lemon::ignore_unused_variable_warning(heap2);
   279 
   280           int s = heap.size();
   281           ::lemon::ignore_unused_variable_warning(s);
   282           bool e = heap.empty();
   283           ::lemon::ignore_unused_variable_warning(e);
   284 
   285           prio = heap.prio();
   286           item = heap.top();
   287           prio = heap[item];
   288           own_prio = heap.prio();
   289           own_item = heap.top();
   290           own_prio = heap[own_item];
   291 
   292           heap.push(item, prio);
   293           heap.push(own_item, own_prio);
   294           heap.pop();
   295 
   296           heap.set(item, prio);
   297           heap.decrease(item, prio);
   298           heap.increase(item, prio);
   299           heap.set(own_item, own_prio);
   300           heap.decrease(own_item, own_prio);
   301           heap.increase(own_item, own_prio);
   302 
   303           heap.erase(item);
   304           heap.erase(own_item);
   305           heap.clear();
   306 
   307           own_state = heap.state(own_item);
   308           heap.state(own_item, own_state);
   309 
   310           own_state = _Heap::PRE_HEAP;
   311           own_state = _Heap::IN_HEAP;
   312           own_state = _Heap::POST_HEAP;
   313         }
   314 
   315         _Heap& heap;
   316         ItemIntMap& map;
   317         Constraints() {}
   318       };
   319     };
   320 
   321     /// @}
   322   } // namespace lemon
   323 }
   324 #endif