COIN-OR::LEMON - Graph Library

Changeset 750:bb3392fe91f2 in lemon for lemon/kary_heap.h


Ignore:
Timestamp:
07/09/09 04:07:08 (10 years ago)
Author:
Peter Kovacs <kpeter@…>
Branch:
default
Phase:
public
Message:

Improve and unify the doc + names in the new heaps (#301)

File:
1 edited

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  • lemon/kary_heap.h

    r748 r750  
    1 /* -*- C++ -*-
    2  *
    3  * This file is a part of LEMON, a generic C++ optimization library
    4  *
    5  * Copyright (C) 2003-2008
     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
    66 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
    77 * (Egervary Research Group on Combinatorial Optimization, EGRES).
     
    2020#define LEMON_KARY_HEAP_H
    2121
    22 ///\ingroup auxdat
     22///\ingroup heaps
    2323///\file
    24 ///\brief Kary Heap implementation.
    25 
    26 #include <iostream>
     24///\brief Fourary heap implementation.
     25
    2726#include <vector>
    2827#include <utility>
     
    3130namespace lemon {
    3231
    33   ///\ingroup auxdat
    34   ///
    35   ///\brief A Kary Heap implementation.
    36   ///
    37   ///This class implements the \e Kary \e heap data structure. A \e heap
    38   ///is a data structure for storing items with specified values called \e
    39   ///priorities in such a way that finding the item with minimum priority is
    40   ///efficient. \c Compare specifies the ordering of the priorities. In a heap
    41   ///one can change the priority of an item, add or erase an item, etc.
    42   ///
    43   ///\param _Prio Type of the priority of the items.
    44   ///\param _ItemIntMap A read and writable Item int map, used internally
    45   ///to handle the cross references.
    46   ///\param _Compare A class for the ordering of the priorities. The
    47   ///default is \c std::less<_Prio>.
    48   ///
    49   ///\sa FibHeap
    50   ///\sa Dijkstra
    51   ///\author Dorian Batha
    52 
    53   template <typename _Prio, typename _ItemIntMap,
    54             typename _Compare = std::less<_Prio> >
    55 
     32  /// \ingroup heaps
     33  ///
     34  ///\brief K-ary heap data structure.
     35  ///
     36  /// This class implements the \e K-ary \e heap data structure.
     37  /// It fully conforms to the \ref concepts::Heap "heap concept".
     38  ///
     39  /// The \ref KaryHeap "K-ary heap" is a generalization of the
     40  /// \ref BinHeap "binary heap" structure, its nodes have at most
     41  /// \c K children, instead of two.
     42  /// \ref BinHeap and \ref FouraryHeap are specialized implementations
     43  /// of this structure for <tt>K=2</tt> and <tt>K=4</tt>, respectively.
     44  ///
     45  /// \tparam PR Type of the priorities of the items.
     46  /// \tparam IM A read-writable item map with \c int values, used
     47  /// internally to handle the cross references.
     48  /// \tparam CMP A functor class for comparing the priorities.
     49  /// The default is \c std::less<PR>.
     50  ///
     51  ///\sa BinHeap
     52  ///\sa FouraryHeap
     53#ifdef DOXYGEN
     54  template <typename PR, typename IM, typename CMP>
     55#else
     56  template <typename PR, typename IM, typename CMP = std::less<PR> >
     57#endif
    5658  class KaryHeap {
    57 
    5859  public:
    59     ///\e
    60     typedef _ItemIntMap ItemIntMap;
    61     ///\e
    62     typedef _Prio Prio;
    63     ///\e
     60    /// Type of the item-int map.
     61    typedef IM ItemIntMap;
     62    /// Type of the priorities.
     63    typedef PR Prio;
     64    /// Type of the items stored in the heap.
    6465    typedef typename ItemIntMap::Key Item;
    65     ///\e
     66    /// Type of the item-priority pairs.
    6667    typedef std::pair<Item,Prio> Pair;
    67     ///\e
    68     typedef _Compare Compare;
    69     ///\e
    70 
    71     /// \brief Type to represent the items states.
    72     ///
    73     /// Each Item element have a state associated to it. It may be "in heap",
    74     /// "pre heap" or "post heap". The latter two are indifferent from the
     68    /// Functor type for comparing the priorities.
     69    typedef CMP Compare;
     70
     71    /// \brief Type to represent the states of the items.
     72    ///
     73    /// Each item has a state associated to it. It can be "in heap",
     74    /// "pre-heap" or "post-heap". The latter two are indifferent from the
    7575    /// heap's point of view, but may be useful to the user.
    7676    ///
    77     /// The ItemIntMap \e should be initialized in such way that it maps
    78     /// PRE_HEAP (-1) to any element to be put in the heap...
     77    /// The item-int map must be initialized in such way that it assigns
     78    /// \c PRE_HEAP (<tt>-1</tt>) to any element to be put in the heap.
    7979    enum State {
    80       IN_HEAP = 0,
    81       PRE_HEAP = -1,
    82       POST_HEAP = -2
     80      IN_HEAP = 0,    ///< = 0.
     81      PRE_HEAP = -1,  ///< = -1.
     82      POST_HEAP = -2  ///< = -2.
    8383    };
    8484
    8585  private:
    86     std::vector<Pair> data;
    87     Compare comp;
    88     ItemIntMap &iim;
    89     int K;
     86    std::vector<Pair> _data;
     87    Compare _comp;
     88    ItemIntMap &_iim;
     89    int _K;
    9090
    9191  public:
    92     /// \brief The constructor.
    93     ///
    94     /// The constructor.
    95     /// \param _iim should be given to the constructor, since it is used
    96     /// internally to handle the cross references. The value of the map
    97     /// should be PRE_HEAP (-1) for each element.
    98     explicit KaryHeap(ItemIntMap &_iim, const int &_K=32) : iim(_iim), K(_K) {}
    99 
    100     /// \brief The constructor.
    101     ///
    102     /// The constructor.
    103     /// \param _iim should be given to the constructor, since it is used
    104     /// internally to handle the cross references. The value of the map
    105     /// should be PRE_HEAP (-1) for each element.
    106     ///
    107     /// \param _comp The comparator function object.
    108     KaryHeap(ItemIntMap &_iim, const Compare &_comp, const int &_K=32)
    109       : iim(_iim), comp(_comp), K(_K) {}
    110 
    111 
    112     /// The number of items stored in the heap.
    113     ///
    114     /// \brief Returns the number of items stored in the heap.
    115     int size() const { return data.size(); }
    116 
    117     /// \brief Checks if the heap stores no items.
    118     ///
    119     /// Returns \c true if and only if the heap stores no items.
    120     bool empty() const { return data.empty(); }
    121 
    122     /// \brief Make empty this heap.
    123     ///
    124     /// Make empty this heap. It does not change the cross reference map.
    125     /// If you want to reuse what is not surely empty you should first clear
    126     /// the heap and after that you should set the cross reference map for
    127     /// each item to \c PRE_HEAP.
    128     void clear() { data.clear(); }
     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    explicit KaryHeap(ItemIntMap &map, int K=32) : _iim(map), _K(K) {}
     99
     100    /// \brief Constructor.
     101    ///
     102    /// Constructor.
     103    /// \param map A map that assigns \c int values to the items.
     104    /// It is used internally to handle the cross references.
     105    /// The assigned value must be \c PRE_HEAP (<tt>-1</tt>) for each item.
     106    /// \param comp The function object used for comparing the priorities.
     107    KaryHeap(ItemIntMap &map, const Compare &comp, int K=32)
     108      : _iim(map), _comp(comp), _K(K) {}
     109
     110    /// \brief The number of items stored in the heap.
     111    ///
     112    /// This function returns the number of items stored in the heap.
     113    int size() const { return _data.size(); }
     114
     115    /// \brief Check if the heap is empty.
     116    ///
     117    /// This function returns \c true if the heap is empty.
     118    bool empty() const { return _data.empty(); }
     119
     120    /// \brief Make the heap empty.
     121    ///
     122    /// This functon makes the heap empty.
     123    /// It does not change the cross reference map. If you want to reuse
     124    /// a heap that is not surely empty, you should first clear it and
     125    /// then you should set the cross reference map to \c PRE_HEAP
     126    /// for each item.
     127    void clear() { _data.clear(); }
    129128
    130129  private:
    131     int parent(int i) { return (i-1)/K; }
    132     int first_child(int i) { return K*i+1; }
     130    int parent(int i) { return (i-1)/_K; }
     131    int firstChild(int i) { return _K*i+1; }
    133132
    134133    bool less(const Pair &p1, const Pair &p2) const {
    135       return comp(p1.second, p2.second);
    136     }
    137 
    138     int find_min(const int child, const int length) {
     134      return _comp(p1.second, p2.second);
     135    }
     136
     137    int findMin(const int child, const int length) {
    139138      int min=child, i=1;
    140       while( i<K && child+i<length ) {
    141         if( less(data[child+i], data[min]) )
     139      while( i<_K && child+i<length ) {
     140        if( less(_data[child+i], _data[min]) )
    142141          min=child+i;
    143142        ++i;
     
    146145    }
    147146
    148     void bubble_up(int hole, Pair p) {
     147    void bubbleUp(int hole, Pair p) {
    149148      int par = parent(hole);
    150       while( hole>0 && less(p,data[par]) ) {
    151         move(data[par],hole);
     149      while( hole>0 && less(p,_data[par]) ) {
     150        move(_data[par],hole);
    152151        hole = par;
    153152        par = parent(hole);
     
    156155    }
    157156
    158     void bubble_down(int hole, Pair p, int length) {
     157    void bubbleDown(int hole, Pair p, int length) {
    159158      if( length>1 ) {
    160         int child = first_child(hole);
     159        int child = firstChild(hole);
    161160        while( child<length ) {
    162           child = find_min(child, length);
    163           if( !less(data[child], p) )
     161          child = findMin(child, length);
     162          if( !less(_data[child], p) )
    164163            goto ok;
    165           move(data[child], hole);
     164          move(_data[child], hole);
    166165          hole = child;
    167           child = first_child(hole);
     166          child = firstChild(hole);
    168167        }
    169168      }
     
    173172
    174173    void move(const Pair &p, int i) {
    175       data[i] = p;
    176       iim.set(p.first, i);
     174      _data[i] = p;
     175      _iim.set(p.first, i);
    177176    }
    178177
     
    180179    /// \brief Insert a pair of item and priority into the heap.
    181180    ///
    182     /// Adds \c p.first to the heap with priority \c p.second.
     181    /// This function inserts \c p.first to the heap with priority
     182    /// \c p.second.
    183183    /// \param p The pair to insert.
     184    /// \pre \c p.first must not be stored in the heap.
    184185    void push(const Pair &p) {
    185       int n = data.size();
    186       data.resize(n+1);
    187       bubble_up(n, p);
    188     }
    189 
    190     /// \brief Insert an item into the heap with the given heap.
    191     ///
    192     /// Adds \c i to the heap with priority \c p.
     186      int n = _data.size();
     187      _data.resize(n+1);
     188      bubbleUp(n, p);
     189    }
     190
     191    /// \brief Insert an item into the heap with the given priority.
     192    ///
     193    /// This function inserts the given item into the heap with the
     194    /// given priority.
    193195    /// \param i The item to insert.
    194196    /// \param p The priority of the item.
     197    /// \pre \e i must not be stored in the heap.
    195198    void push(const Item &i, const Prio &p) { push(Pair(i,p)); }
    196199
    197     /// \brief Returns the item with minimum priority relative to \c Compare.
    198     ///
    199     /// This method returns the item with minimum priority relative to \c
    200     /// Compare.
    201     /// \pre The heap must be nonempty.
    202     Item top() const { return data[0].first; }
    203 
    204     /// \brief Returns the minimum priority relative to \c Compare.
    205     ///
    206     /// It returns the minimum priority relative to \c Compare.
    207     /// \pre The heap must be nonempty.
    208     Prio prio() const { return data[0].second; }
    209 
    210     /// \brief Deletes the item with minimum priority relative to \c Compare.
    211     ///
    212     /// This method deletes the item with minimum priority relative to \c
    213     /// Compare from the heap.
     200    /// \brief Return the item having minimum priority.
     201    ///
     202    /// This function returns the item having minimum priority.
     203    /// \pre The heap must be non-empty.
     204    Item top() const { return _data[0].first; }
     205
     206    /// \brief The minimum priority.
     207    ///
     208    /// This function returns the minimum priority.
     209    /// \pre The heap must be non-empty.
     210    Prio prio() const { return _data[0].second; }
     211
     212    /// \brief Remove the item having minimum priority.
     213    ///
     214    /// This function removes the item having minimum priority.
    214215    /// \pre The heap must be non-empty.
    215216    void pop() {
    216       int n = data.size()-1;
    217       iim.set(data[0].first, POST_HEAP);
    218       if (n>0) bubble_down(0, data[n], n);
    219       data.pop_back();
    220     }
    221 
    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.
     217      int n = _data.size()-1;
     218      _iim.set(_data[0].first, POST_HEAP);
     219      if (n>0) bubbleDown(0, _data[n], n);
     220      _data.pop_back();
     221    }
     222
     223    /// \brief Remove the given item from the heap.
     224    ///
     225    /// This function removes the given item from the heap if it is
     226    /// already stored.
     227    /// \param i The item to delete.
     228    /// \pre \e i must be in the heap.
    227229    void erase(const Item &i) {
    228       int h = iim[i];
    229       int n = data.size()-1;
    230       iim.set(data[h].first, POST_HEAP);
     230      int h = _iim[i];
     231      int n = _data.size()-1;
     232      _iim.set(_data[h].first, POST_HEAP);
    231233      if( h<n ) {
    232         if( less(data[parent(h)], data[n]) )
    233           bubble_down(h, data[n], n);
     234        if( less(_data[parent(h)], _data[n]) )
     235          bubbleDown(h, _data[n], n);
    234236        else
    235           bubble_up(h, data[n]);
    236       }
    237       data.pop_back();
    238     }
    239 
    240 
    241     /// \brief Returns the priority of \c i.
    242     ///
    243     /// This function returns the priority of item \c i.
    244     /// \pre \c i must be in the heap.
    245     /// \param i The item.
     237          bubbleUp(h, _data[n]);
     238      }
     239      _data.pop_back();
     240    }
     241
     242    /// \brief The priority of the given item.
     243    ///
     244    /// This function returns the priority of the given item.
     245    /// \param i The item.
     246    /// \pre \e i must be in the heap.
    246247    Prio operator[](const Item &i) const {
    247       int idx = iim[i];
    248       return data[idx].second;
    249     }
    250 
    251     /// \brief \c i gets to the heap with priority \c p independently
    252     /// if \c i was already there.
    253     ///
    254     /// This method calls \ref push(\c i, \c p) if \c i is not stored
    255     /// in the heap and sets the priority of \c i to \c p otherwise.
     248      int idx = _iim[i];
     249      return _data[idx].second;
     250    }
     251
     252    /// \brief Set the priority of an item or insert it, if it is
     253    /// not stored in the heap.
     254    ///
     255    /// This method sets the priority of the given item if it is
     256    /// already stored in the heap. Otherwise it inserts the given
     257    /// item into the heap with the given priority.
    256258    /// \param i The item.
    257259    /// \param p The priority.
    258260    void set(const Item &i, const Prio &p) {
    259       int idx = iim[i];
     261      int idx = _iim[i];
    260262      if( idx<0 )
    261263        push(i,p);
    262       else if( comp(p, data[idx].second) )
    263         bubble_up(idx, Pair(i,p));
     264      else if( _comp(p, _data[idx].second) )
     265        bubbleUp(idx, Pair(i,p));
    264266      else
    265         bubble_down(idx, Pair(i,p), data.size());
    266     }
    267 
    268     /// \brief Decreases the priority of \c i to \c p.
    269     ///
    270     /// This method decreases the priority of item \c i to \c p.
    271     /// \pre \c i must be stored in the heap with priority at least \c
    272     /// p relative to \c Compare.
     267        bubbleDown(idx, Pair(i,p), _data.size());
     268    }
     269
     270    /// \brief Decrease the priority of an item to the given value.
     271    ///
     272    /// This function decreases the priority of an item to the given value.
    273273    /// \param i The item.
    274274    /// \param p The priority.
     275    /// \pre \e i must be stored in the heap with priority at least \e p.
    275276    void decrease(const Item &i, const Prio &p) {
    276       int idx = iim[i];
    277       bubble_up(idx, Pair(i,p));
    278     }
    279 
    280     /// \brief Increases the priority of \c i to \c p.
    281     ///
    282     /// This method sets the priority of item \c i to \c p.
    283     /// \pre \c i must be stored in the heap with priority at most \c
    284     /// p relative to \c Compare.
     277      int idx = _iim[i];
     278      bubbleUp(idx, Pair(i,p));
     279    }
     280
     281    /// \brief Increase the priority of an item to the given value.
     282    ///
     283    /// This function increases the priority of an item to the given value.
    285284    /// \param i The item.
    286285    /// \param p The priority.
     286    /// \pre \e i must be stored in the heap with priority at most \e p.
    287287    void increase(const Item &i, const Prio &p) {
    288       int idx = iim[i];
    289       bubble_down(idx, Pair(i,p), data.size());
    290     }
    291 
    292     /// \brief Returns if \c item is in, has already been in, or has
    293     /// never been in the heap.
    294     ///
    295     /// This method returns PRE_HEAP if \c item has never been in the
    296     /// heap, IN_HEAP if it is in the heap at the moment, and POST_HEAP
    297     /// otherwise. In the latter case it is possible that \c item will
    298     /// get back to the heap again.
     288      int idx = _iim[i];
     289      bubbleDown(idx, Pair(i,p), _data.size());
     290    }
     291
     292    /// \brief Return the state of an item.
     293    ///
     294    /// This method returns \c PRE_HEAP if the given item has never
     295    /// been in the heap, \c IN_HEAP if it is in the heap at the moment,
     296    /// and \c POST_HEAP otherwise.
     297    /// In the latter case it is possible that the item will get back
     298    /// to the heap again.
    299299    /// \param i The item.
    300300    State state(const Item &i) const {
    301       int s = iim[i];
     301      int s = _iim[i];
    302302      if (s>=0) s=0;
    303303      return State(s);
    304304    }
    305305
    306     /// \brief Sets the state of the \c item in the heap.
    307     ///
    308     /// Sets the state of the \c item in the heap. It can be used to
    309     /// manually clear the heap when it is important to achive the
    310     /// better time complexity.
     306    /// \brief Set the state of an item in the heap.
     307    ///
     308    /// This function sets the state of the given item in the heap.
     309    /// It can be used to manually clear the heap when it is important
     310    /// to achive better time complexity.
    311311    /// \param i The item.
    312312    /// \param st The state. It should not be \c IN_HEAP.
    313313    void state(const Item& i, State st) {
    314314      switch (st) {
    315       case POST_HEAP:
    316       case PRE_HEAP:
    317         if (state(i) == IN_HEAP) erase(i);
    318         iim[i] = st;
    319         break;
    320       case IN_HEAP:
    321         break;
    322       }
    323     }
    324 
    325     /// \brief Replaces an item in the heap.
    326     ///
    327     /// The \c i item is replaced with \c j item. The \c i item should
    328     /// be in the heap, while the \c j should be out of the heap. The
    329     /// \c i item will out of the heap and \c j will be in the heap
    330     /// with the same prioriority as prevoiusly the \c i item.
     315        case POST_HEAP:
     316        case PRE_HEAP:
     317          if (state(i) == IN_HEAP) erase(i);
     318          _iim[i] = st;
     319          break;
     320        case IN_HEAP:
     321          break;
     322      }
     323    }
     324
     325    /// \brief Replace an item in the heap.
     326    ///
     327    /// This function replaces item \c i with item \c j.
     328    /// Item \c i must be in the heap, while \c j must be out of the heap.
     329    /// After calling this method, item \c i will be out of the
     330    /// heap and \c j will be in the heap with the same prioriority
     331    /// as item \c i had before.
    331332    void replace(const Item& i, const Item& j) {
    332       int idx=iim[i];
    333       iim.set(i, iim[j]);
    334       iim.set(j, idx);
    335       data[idx].first=j;
     333      int idx=_iim[i];
     334      _iim.set(i, _iim[j]);
     335      _iim.set(j, idx);
     336      _data[idx].first=j;
    336337    }
    337338
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