lemon/concepts/heap.h
author Alpar Juttner <alpar@cs.elte.hu>
Mon, 23 Feb 2009 11:49:57 +0000
changeset 526 28b154307c0d
parent 440 88ed40ad0d4f
child 529 f5bc148f7e1f
permissions -rw-r--r--
DIMACS solver utility (#226)
     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) 2003-2009
     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 ///\ingroup concept
    20 ///\file
    21 ///\brief The concept of heaps.
    22 
    23 #ifndef LEMON_CONCEPT_HEAP_H
    24 #define LEMON_CONCEPT_HEAP_H
    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     /// Concept class describing the main interface of heaps.
    39     template <typename Priority, typename ItemIntMap>
    40     class Heap {
    41     public:
    42 
    43       /// Type of the items stored in the heap.
    44       typedef typename ItemIntMap::Key Item;
    45 
    46       /// Type of the priorities.
    47       typedef Priority Prio;
    48 
    49       /// \brief Type to represent the states of the items.
    50       ///
    51       /// Each item has a state associated to it. It can be "in heap",
    52       /// "pre heap" or "post heap". The later two are indifferent
    53       /// from the point of view of the heap, but may be useful for
    54       /// the user.
    55       ///
    56       /// The \c ItemIntMap must be initialized in such a way, that it
    57       /// assigns \c PRE_HEAP (<tt>-1</tt>) to every item.
    58       enum State {
    59         IN_HEAP = 0,
    60         PRE_HEAP = -1,
    61         POST_HEAP = -2
    62       };
    63 
    64       /// \brief The constructor.
    65       ///
    66       /// The constructor.
    67       /// \param map A map that assigns \c int values to keys of type
    68       /// \c Item. It is used internally by the heap implementations to
    69       /// handle the cross references. The assigned value must be
    70       /// \c PRE_HEAP (<tt>-1</tt>) for every item.
    71       explicit Heap(ItemIntMap &map) {}
    72 
    73       /// \brief The number of items stored in the heap.
    74       ///
    75       /// Returns the number of items stored in the heap.
    76       int size() const { return 0; }
    77 
    78       /// \brief Checks if the heap is empty.
    79       ///
    80       /// Returns \c true if the heap is empty.
    81       bool empty() const { return false; }
    82 
    83       /// \brief Makes the heap empty.
    84       ///
    85       /// Makes the heap empty.
    86       void clear();
    87 
    88       /// \brief Inserts an item into the heap with the given priority.
    89       ///
    90       /// Inserts the given item into the heap with the given priority.
    91       /// \param i The item to insert.
    92       /// \param p The priority of the item.
    93       void push(const Item &i, const Prio &p) {}
    94 
    95       /// \brief Returns the item having minimum priority.
    96       ///
    97       /// Returns the item having minimum priority.
    98       /// \pre The heap must be non-empty.
    99       Item top() const {}
   100 
   101       /// \brief The minimum priority.
   102       ///
   103       /// Returns the minimum priority.
   104       /// \pre The heap must be non-empty.
   105       Prio prio() const {}
   106 
   107       /// \brief Removes the item having minimum priority.
   108       ///
   109       /// Removes the item having minimum priority.
   110       /// \pre The heap must be non-empty.
   111       void pop() {}
   112 
   113       /// \brief Removes an item from the heap.
   114       ///
   115       /// Removes the given item from the heap if it is already stored.
   116       /// \param i The item to delete.
   117       void erase(const Item &i) {}
   118 
   119       /// \brief The priority of an item.
   120       ///
   121       /// Returns the priority of the given item.
   122       /// \pre \c i must be in the heap.
   123       /// \param i The item.
   124       Prio operator[](const Item &i) const {}
   125 
   126       /// \brief Sets the priority of an item or inserts it, if it is
   127       /// not stored in the heap.
   128       ///
   129       /// This method sets the priority of the given item if it is
   130       /// already stored in the heap.
   131       /// Otherwise it inserts the given item with the given priority.
   132       ///
   133       /// \param i The item.
   134       /// \param p The priority.
   135       void set(const Item &i, const Prio &p) {}
   136 
   137       /// \brief Decreases the priority of an item to the given value.
   138       ///
   139       /// Decreases the priority of an item to the given value.
   140       /// \pre \c i must be stored in the heap with priority at least \c p.
   141       /// \param i The item.
   142       /// \param p The priority.
   143       void decrease(const Item &i, const Prio &p) {}
   144 
   145       /// \brief Increases the priority of an item to the given value.
   146       ///
   147       /// Increases the priority of an item to the given value.
   148       /// \pre \c i must be stored in the heap with priority at most \c p.
   149       /// \param i The item.
   150       /// \param p The priority.
   151       void increase(const Item &i, const Prio &p) {}
   152 
   153       /// \brief Returns if an item is in, has already been in, or has
   154       /// never been in the heap.
   155       ///
   156       /// This method returns \c PRE_HEAP if the given item has never
   157       /// been in the heap, \c IN_HEAP if it is in the heap at the moment,
   158       /// and \c POST_HEAP otherwise.
   159       /// In the latter case it is possible that the item will get back
   160       /// to the heap again.
   161       /// \param i The item.
   162       State state(const Item &i) const {}
   163 
   164       /// \brief Sets the state of an item in the heap.
   165       ///
   166       /// Sets the state of the given item in the heap. It can be used
   167       /// to manually clear the heap when it is important to achive the
   168       /// better time complexity.
   169       /// \param i The item.
   170       /// \param st The state. It should not be \c IN_HEAP.
   171       void state(const Item& i, State st) {}
   172 
   173 
   174       template <typename _Heap>
   175       struct Constraints {
   176       public:
   177         void constraints() {
   178           typedef typename _Heap::Item OwnItem;
   179           typedef typename _Heap::Prio OwnPrio;
   180           typedef typename _Heap::State OwnState;
   181 
   182           Item item;
   183           Prio prio;
   184           item=Item();
   185           prio=Prio();
   186           ignore_unused_variable_warning(item);
   187           ignore_unused_variable_warning(prio);
   188 
   189           OwnItem own_item;
   190           OwnPrio own_prio;
   191           OwnState own_state;
   192           own_item=Item();
   193           own_prio=Prio();
   194           ignore_unused_variable_warning(own_item);
   195           ignore_unused_variable_warning(own_prio);
   196           ignore_unused_variable_warning(own_state);
   197 
   198           _Heap heap1(map);
   199           _Heap heap2 = heap1;
   200           ignore_unused_variable_warning(heap1);
   201           ignore_unused_variable_warning(heap2);
   202 
   203           int s = heap.size();
   204           ignore_unused_variable_warning(s);
   205           bool e = heap.empty();
   206           ignore_unused_variable_warning(e);
   207 
   208           prio = heap.prio();
   209           item = heap.top();
   210           prio = heap[item];
   211           own_prio = heap.prio();
   212           own_item = heap.top();
   213           own_prio = heap[own_item];
   214 
   215           heap.push(item, prio);
   216           heap.push(own_item, own_prio);
   217           heap.pop();
   218 
   219           heap.set(item, prio);
   220           heap.decrease(item, prio);
   221           heap.increase(item, prio);
   222           heap.set(own_item, own_prio);
   223           heap.decrease(own_item, own_prio);
   224           heap.increase(own_item, own_prio);
   225 
   226           heap.erase(item);
   227           heap.erase(own_item);
   228           heap.clear();
   229 
   230           own_state = heap.state(own_item);
   231           heap.state(own_item, own_state);
   232 
   233           own_state = _Heap::PRE_HEAP;
   234           own_state = _Heap::IN_HEAP;
   235           own_state = _Heap::POST_HEAP;
   236         }
   237 
   238         _Heap& heap;
   239         ItemIntMap& map;
   240       };
   241     };
   242 
   243     /// @}
   244   } // namespace lemon
   245 }
   246 #endif // LEMON_CONCEPT_PATH_H