COIN-OR::LEMON - Graph Library

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  • lemon/bin_heap.h

    r584 r711  
    2020#define LEMON_BIN_HEAP_H
    2121
    22 ///\ingroup auxdat
     22///\ingroup heaps
    2323///\file
    24 ///\brief Binary Heap implementation.
     24///\brief Binary heap implementation.
    2525
    2626#include <vector>
     
    3030namespace lemon {
    3131
    32   ///\ingroup auxdat
     32  /// \ingroup heaps
    3333  ///
    34   ///\brief A Binary Heap implementation.
     34  /// \brief Binary heap data structure.
    3535  ///
    36   ///This class implements the \e binary \e heap data structure.
    37   ///
    38   ///A \e heap is a data structure for storing items with specified values
    39   ///called \e priorities in such a way that finding the item with minimum
    40   ///priority is efficient. \c Comp specifies the ordering of the priorities.
    41   ///In a heap one can change the priority of an item, add or erase an
    42   ///item, etc.
     36  /// This class implements the \e binary \e heap data structure.
     37  /// It fully conforms to the \ref concepts::Heap "heap concept".
    4338  ///
    44   ///\tparam PR Type of the priority of the items.
    45   ///\tparam IM A read and writable item map with int values, used internally
    46   ///to handle the cross references.
    47   ///\tparam Comp A functor class for the ordering of the priorities.
    48   ///The default is \c std::less<PR>.
    49   ///
    50   ///\sa FibHeap
    51   ///\sa Dijkstra
    52   template <typename PR, typename IM, typename Comp = std::less<PR> >
     39  /// \tparam PR Type of the priorities of the items.
     40  /// \tparam IM A read-writable item map with \c int values, used
     41  /// internally to handle the cross references.
     42  /// \tparam CMP A functor class for comparing the priorities.
     43  /// The default is \c std::less<PR>.
     44#ifdef DOXYGEN
     45  template <typename PR, typename IM, typename CMP>
     46#else
     47  template <typename PR, typename IM, typename CMP = std::less<PR> >
     48#endif
    5349  class BinHeap {
    54 
    5550  public:
    56     ///\e
     51
     52    /// Type of the item-int map.
    5753    typedef IM ItemIntMap;
    58     ///\e
     54    /// Type of the priorities.
    5955    typedef PR Prio;
    60     ///\e
     56    /// Type of the items stored in the heap.
    6157    typedef typename ItemIntMap::Key Item;
    62     ///\e
     58    /// Type of the item-priority pairs.
    6359    typedef std::pair<Item,Prio> Pair;
    64     ///\e
    65     typedef Comp Compare;
    66 
    67     /// \brief Type to represent the items states.
    68     ///
    69     /// Each Item element have a state associated to it. It may be "in heap",
    70     /// "pre heap" or "post heap". The latter two are indifferent from the
     60    /// Functor type for comparing the priorities.
     61    typedef CMP Compare;
     62
     63    /// \brief Type to represent the states of the items.
     64    ///
     65    /// Each item has a state associated to it. It can be "in heap",
     66    /// "pre-heap" or "post-heap". The latter two are indifferent from the
    7167    /// heap's point of view, but may be useful to the user.
    7268    ///
     
    8581
    8682  public:
    87     /// \brief The constructor.
    88     ///
    89     /// The constructor.
    90     /// \param map should be given to the constructor, since it is used
    91     /// internally to handle the cross references. The value of the map
    92     /// must be \c PRE_HEAP (<tt>-1</tt>) for every item.
     83
     84    /// \brief Constructor.
     85    ///
     86    /// Constructor.
     87    /// \param map A map that assigns \c int values to the items.
     88    /// It is used internally to handle the cross references.
     89    /// The assigned value must be \c PRE_HEAP (<tt>-1</tt>) for each item.
    9390    explicit BinHeap(ItemIntMap &map) : _iim(map) {}
    9491
    95     /// \brief The constructor.
    96     ///
    97     /// The constructor.
    98     /// \param map should be given to the constructor, since it is used
    99     /// internally to handle the cross references. The value of the map
    100     /// should be PRE_HEAP (-1) for each element.
    101     ///
    102     /// \param comp The comparator function object.
     92    /// \brief Constructor.
     93    ///
     94    /// Constructor.
     95    /// \param map A map that assigns \c int values to the items.
     96    /// It is used internally to handle the cross references.
     97    /// The assigned value must be \c PRE_HEAP (<tt>-1</tt>) for each item.
     98    /// \param comp The function object used for comparing the priorities.
    10399    BinHeap(ItemIntMap &map, const Compare &comp)
    104100      : _iim(map), _comp(comp) {}
    105101
    106102
    107     /// The number of items stored in the heap.
    108     ///
    109     /// \brief Returns the number of items stored in the heap.
     103    /// \brief The number of items stored in the heap.
     104    ///
     105    /// This function returns the number of items stored in the heap.
    110106    int size() const { return _data.size(); }
    111107
    112     /// \brief Checks if the heap stores no items.
    113     ///
    114     /// Returns \c true if and only if the heap stores no items.
     108    /// \brief Check if the heap is empty.
     109    ///
     110    /// This function returns \c true if the heap is empty.
    115111    bool empty() const { return _data.empty(); }
    116112
    117     /// \brief Make empty this heap.
    118     ///
    119     /// Make empty this heap. It does not change the cross reference map.
    120     /// If you want to reuse what is not surely empty you should first clear
    121     /// the heap and after that you should set the cross reference map for
    122     /// each item to \c PRE_HEAP.
     113    /// \brief Make the heap empty.
     114    ///
     115    /// This functon makes the heap empty.
     116    /// It does not change the cross reference map. If you want to reuse
     117    /// a heap that is not surely empty, you should first clear it and
     118    /// then you should set the cross reference map to \c PRE_HEAP
     119    /// for each item.
    123120    void clear() {
    124121      _data.clear();
     
    128125    static int parent(int i) { return (i-1)/2; }
    129126
    130     static int second_child(int i) { return 2*i+2; }
     127    static int secondChild(int i) { return 2*i+2; }
    131128    bool less(const Pair &p1, const Pair &p2) const {
    132129      return _comp(p1.second, p2.second);
    133130    }
    134131
    135     int bubble_up(int hole, Pair p) {
     132    int bubbleUp(int hole, Pair p) {
    136133      int par = parent(hole);
    137134      while( hole>0 && less(p,_data[par]) ) {
     
    144141    }
    145142
    146     int bubble_down(int hole, Pair p, int length) {
    147       int child = second_child(hole);
     143    int bubbleDown(int hole, Pair p, int length) {
     144      int child = secondChild(hole);
    148145      while(child < length) {
    149146        if( less(_data[child-1], _data[child]) ) {
     
    154151        move(_data[child], hole);
    155152        hole = child;
    156         child = second_child(hole);
     153        child = secondChild(hole);
    157154      }
    158155      child--;
     
    172169
    173170  public:
     171
    174172    /// \brief Insert a pair of item and priority into the heap.
    175173    ///
    176     /// Adds \c p.first to the heap with priority \c p.second.
     174    /// This function inserts \c p.first to the heap with priority
     175    /// \c p.second.
    177176    /// \param p The pair to insert.
     177    /// \pre \c p.first must not be stored in the heap.
    178178    void push(const Pair &p) {
    179179      int n = _data.size();
    180180      _data.resize(n+1);
    181       bubble_up(n, p);
    182     }
    183 
    184     /// \brief Insert an item into the heap with the given heap.
    185     ///
    186     /// Adds \c i to the heap with priority \c p.
     181      bubbleUp(n, p);
     182    }
     183
     184    /// \brief Insert an item into the heap with the given priority.
     185    ///
     186    /// This function inserts the given item into the heap with the
     187    /// given priority.
    187188    /// \param i The item to insert.
    188189    /// \param p The priority of the item.
     190    /// \pre \e i must not be stored in the heap.
    189191    void push(const Item &i, const Prio &p) { push(Pair(i,p)); }
    190192
    191     /// \brief Returns the item with minimum priority relative to \c Compare.
    192     ///
    193     /// This method returns the item with minimum priority relative to \c
    194     /// Compare.
    195     /// \pre The heap must be nonempty.
     193    /// \brief Return the item having minimum priority.
     194    ///
     195    /// This function returns the item having minimum priority.
     196    /// \pre The heap must be non-empty.
    196197    Item top() const {
    197198      return _data[0].first;
    198199    }
    199200
    200     /// \brief Returns the minimum priority relative to \c Compare.
    201     ///
    202     /// It returns the minimum priority relative to \c Compare.
    203     /// \pre The heap must be nonempty.
     201    /// \brief The minimum priority.
     202    ///
     203    /// This function returns the minimum priority.
     204    /// \pre The heap must be non-empty.
    204205    Prio prio() const {
    205206      return _data[0].second;
    206207    }
    207208
    208     /// \brief Deletes the item with minimum priority relative to \c Compare.
    209     ///
    210     /// This method deletes the item with minimum priority relative to \c
    211     /// Compare from the heap.
     209    /// \brief Remove the item having minimum priority.
     210    ///
     211    /// This function removes the item having minimum priority.
    212212    /// \pre The heap must be non-empty.
    213213    void pop() {
     
    215215      _iim.set(_data[0].first, POST_HEAP);
    216216      if (n > 0) {
    217         bubble_down(0, _data[n], n);
     217        bubbleDown(0, _data[n], n);
    218218      }
    219219      _data.pop_back();
    220220    }
    221221
    222     /// \brief Deletes \c i from the heap.
    223     ///
    224     /// This method deletes item \c i from the heap.
    225     /// \param i The item to erase.
    226     /// \pre The item should be in the heap.
     222    /// \brief Remove the given item from the heap.
     223    ///
     224    /// This function removes the given item from the heap if it is
     225    /// already stored.
     226    /// \param i The item to delete.
     227    /// \pre \e i must be in the heap.
    227228    void erase(const Item &i) {
    228229      int h = _iim[i];
     
    230231      _iim.set(_data[h].first, POST_HEAP);
    231232      if( h < n ) {
    232         if ( bubble_up(h, _data[n]) == h) {
    233           bubble_down(h, _data[n], n);
     233        if ( bubbleUp(h, _data[n]) == h) {
     234          bubbleDown(h, _data[n], n);
    234235        }
    235236      }
     
    237238    }
    238239
    239 
    240     /// \brief Returns the priority of \c i.
    241     ///
    242     /// This function returns the priority of item \c i.
    243     /// \param i The item.
    244     /// \pre \c i must be in the heap.
     240    /// \brief The priority of the given item.
     241    ///
     242    /// This function returns the priority of the given item.
     243    /// \param i The item.
     244    /// \pre \e i must be in the heap.
    245245    Prio operator[](const Item &i) const {
    246246      int idx = _iim[i];
     
    248248    }
    249249
    250     /// \brief \c i gets to the heap with priority \c p independently
    251     /// if \c i was already there.
    252     ///
    253     /// This method calls \ref push(\c i, \c p) if \c i is not stored
    254     /// in the heap and sets the priority of \c i to \c p otherwise.
     250    /// \brief Set the priority of an item or insert it, if it is
     251    /// not stored in the heap.
     252    ///
     253    /// This method sets the priority of the given item if it is
     254    /// already stored in the heap. Otherwise it inserts the given
     255    /// item into the heap with the given priority.
    255256    /// \param i The item.
    256257    /// \param p The priority.
     
    261262      }
    262263      else if( _comp(p, _data[idx].second) ) {
    263         bubble_up(idx, Pair(i,p));
     264        bubbleUp(idx, Pair(i,p));
    264265      }
    265266      else {
    266         bubble_down(idx, Pair(i,p), _data.size());
    267       }
    268     }
    269 
    270     /// \brief Decreases the priority of \c i to \c p.
    271     ///
    272     /// This method decreases the priority of item \c i to \c p.
     267        bubbleDown(idx, Pair(i,p), _data.size());
     268      }
     269    }
     270
     271    /// \brief Decrease the priority of an item to the given value.
     272    ///
     273    /// This function decreases the priority of an item to the given value.
    273274    /// \param i The item.
    274275    /// \param p The priority.
    275     /// \pre \c i must be stored in the heap with priority at least \c
    276     /// p relative to \c Compare.
     276    /// \pre \e i must be stored in the heap with priority at least \e p.
    277277    void decrease(const Item &i, const Prio &p) {
    278278      int idx = _iim[i];
    279       bubble_up(idx, Pair(i,p));
    280     }
    281 
    282     /// \brief Increases the priority of \c i to \c p.
    283     ///
    284     /// This method sets the priority of item \c i to \c p.
     279      bubbleUp(idx, Pair(i,p));
     280    }
     281
     282    /// \brief Increase the priority of an item to the given value.
     283    ///
     284    /// This function increases the priority of an item to the given value.
    285285    /// \param i The item.
    286286    /// \param p The priority.
    287     /// \pre \c i must be stored in the heap with priority at most \c
    288     /// p relative to \c Compare.
     287    /// \pre \e i must be stored in the heap with priority at most \e p.
    289288    void increase(const Item &i, const Prio &p) {
    290289      int idx = _iim[i];
    291       bubble_down(idx, Pair(i,p), _data.size());
    292     }
    293 
    294     /// \brief Returns if \c item is in, has already been in, or has
    295     /// never been in the heap.
    296     ///
    297     /// This method returns PRE_HEAP if \c item has never been in the
    298     /// heap, IN_HEAP if it is in the heap at the moment, and POST_HEAP
    299     /// otherwise. In the latter case it is possible that \c item will
    300     /// get back to the heap again.
     290      bubbleDown(idx, Pair(i,p), _data.size());
     291    }
     292
     293    /// \brief Return the state of an item.
     294    ///
     295    /// This method returns \c PRE_HEAP if the given item has never
     296    /// been in the heap, \c IN_HEAP if it is in the heap at the moment,
     297    /// and \c POST_HEAP otherwise.
     298    /// In the latter case it is possible that the item will get back
     299    /// to the heap again.
    301300    /// \param i The item.
    302301    State state(const Item &i) const {
     
    307306    }
    308307
    309     /// \brief Sets the state of the \c item in the heap.
    310     ///
    311     /// Sets the state of the \c item in the heap. It can be used to
    312     /// manually clear the heap when it is important to achive the
    313     /// better time complexity.
     308    /// \brief Set the state of an item in the heap.
     309    ///
     310    /// This function sets the state of the given item in the heap.
     311    /// It can be used to manually clear the heap when it is important
     312    /// to achive better time complexity.
    314313    /// \param i The item.
    315314    /// \param st The state. It should not be \c IN_HEAP.
     
    328327    }
    329328
    330     /// \brief Replaces an item in the heap.
    331     ///
    332     /// The \c i item is replaced with \c j item. The \c i item should
    333     /// be in the heap, while the \c j should be out of the heap. The
    334     /// \c i item will out of the heap and \c j will be in the heap
    335     /// with the same prioriority as prevoiusly the \c i item.
     329    /// \brief Replace an item in the heap.
     330    ///
     331    /// This function replaces item \c i with item \c j.
     332    /// Item \c i must be in the heap, while \c j must be out of the heap.
     333    /// After calling this method, item \c i will be out of the
     334    /// heap and \c j will be in the heap with the same prioriority
     335    /// as item \c i had before.
    336336    void replace(const Item& i, const Item& j) {
    337337      int idx = _iim[i];
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