lemon/pairing_heap.h
changeset 750 bb3392fe91f2
parent 749 bdc7dfc8c054
child 752 39a5b48bcace
     1.1 --- a/lemon/pairing_heap.h	Thu Jul 09 02:39:47 2009 +0200
     1.2 +++ b/lemon/pairing_heap.h	Thu Jul 09 04:07:08 2009 +0200
     1.3 @@ -1,8 +1,8 @@
     1.4 -/* -*- C++ -*-
     1.5 +/* -*- mode: C++; indent-tabs-mode: nil; -*-
     1.6   *
     1.7 - * This file is a part of LEMON, a generic C++ optimization library
     1.8 + * This file is a part of LEMON, a generic C++ optimization library.
     1.9   *
    1.10 - * Copyright (C) 2003-2008
    1.11 + * Copyright (C) 2003-2009
    1.12   * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
    1.13   * (Egervary Research Group on Combinatorial Optimization, EGRES).
    1.14   *
    1.15 @@ -20,217 +20,223 @@
    1.16  #define LEMON_PAIRING_HEAP_H
    1.17  
    1.18  ///\file
    1.19 -///\ingroup auxdat
    1.20 -///\brief Pairing Heap implementation.
    1.21 +///\ingroup heaps
    1.22 +///\brief Pairing heap implementation.
    1.23  
    1.24  #include <vector>
    1.25 +#include <utility>
    1.26  #include <functional>
    1.27  #include <lemon/math.h>
    1.28  
    1.29  namespace lemon {
    1.30  
    1.31 -  /// \ingroup auxdat
    1.32 +  /// \ingroup heaps
    1.33    ///
    1.34    ///\brief Pairing Heap.
    1.35    ///
    1.36 -  ///This class implements the \e Pairing \e heap data structure. A \e heap
    1.37 -  ///is a data structure for storing items with specified values called \e
    1.38 -  ///priorities in such a way that finding the item with minimum priority is
    1.39 -  ///efficient. \c Compare specifies the ordering of the priorities. In a heap
    1.40 -  ///one can change the priority of an item, add or erase an item, etc.
    1.41 +  /// This class implements the \e pairing \e heap data structure.
    1.42 +  /// It fully conforms to the \ref concepts::Heap "heap concept".
    1.43    ///
    1.44 -  ///The methods \ref increase and \ref erase are not efficient in a Pairing
    1.45 -  ///heap. In case of many calls to these operations, it is better to use a
    1.46 -  ///\ref BinHeap "binary heap".
    1.47 +  /// The methods \ref increase() and \ref erase() are not efficient
    1.48 +  /// in a pairing heap. In case of many calls of these operations,
    1.49 +  /// it is better to use other heap structure, e.g. \ref BinHeap
    1.50 +  /// "binary heap".
    1.51    ///
    1.52 -  ///\param _Prio Type of the priority of the items.
    1.53 -  ///\param _ItemIntMap A read and writable Item int map, used internally
    1.54 -  ///to handle the cross references.
    1.55 -  ///\param _Compare A class for the ordering of the priorities. The
    1.56 -  ///default is \c std::less<_Prio>.
    1.57 -  ///
    1.58 -  ///\sa BinHeap
    1.59 -  ///\sa Dijkstra
    1.60 -  ///\author Dorian Batha
    1.61 -
    1.62 +  /// \tparam PR Type of the priorities of the items.
    1.63 +  /// \tparam IM A read-writable item map with \c int values, used
    1.64 +  /// internally to handle the cross references.
    1.65 +  /// \tparam CMP A functor class for comparing the priorities.
    1.66 +  /// The default is \c std::less<PR>.
    1.67  #ifdef DOXYGEN
    1.68 -  template <typename _Prio,
    1.69 -            typename _ItemIntMap,
    1.70 -            typename _Compare>
    1.71 +  template <typename PR, typename IM, typename CMP>
    1.72  #else
    1.73 -  template <typename _Prio,
    1.74 -            typename _ItemIntMap,
    1.75 -            typename _Compare = std::less<_Prio> >
    1.76 +  template <typename PR, typename IM, typename CMP = std::less<PR> >
    1.77  #endif
    1.78    class PairingHeap {
    1.79    public:
    1.80 -    typedef _ItemIntMap ItemIntMap;
    1.81 -    typedef _Prio Prio;
    1.82 +    /// Type of the item-int map.
    1.83 +    typedef IM ItemIntMap;
    1.84 +    /// Type of the priorities.
    1.85 +    typedef PR Prio;
    1.86 +    /// Type of the items stored in the heap.
    1.87      typedef typename ItemIntMap::Key Item;
    1.88 -    typedef std::pair<Item,Prio> Pair;
    1.89 -    typedef _Compare Compare;
    1.90 +    /// Functor type for comparing the priorities.
    1.91 +    typedef CMP Compare;
    1.92 +
    1.93 +    /// \brief Type to represent the states of the items.
    1.94 +    ///
    1.95 +    /// Each item has a state associated to it. It can be "in heap",
    1.96 +    /// "pre-heap" or "post-heap". The latter two are indifferent from the
    1.97 +    /// heap's point of view, but may be useful to the user.
    1.98 +    ///
    1.99 +    /// The item-int map must be initialized in such way that it assigns
   1.100 +    /// \c PRE_HEAP (<tt>-1</tt>) to any element to be put in the heap.
   1.101 +    enum State {
   1.102 +      IN_HEAP = 0,    ///< = 0.
   1.103 +      PRE_HEAP = -1,  ///< = -1.
   1.104 +      POST_HEAP = -2  ///< = -2.
   1.105 +    };
   1.106  
   1.107    private:
   1.108      class store;
   1.109  
   1.110 -    std::vector<store> container;
   1.111 -    int minimum;
   1.112 -    ItemIntMap &iimap;
   1.113 -    Compare comp;
   1.114 -    int num_items;
   1.115 +    std::vector<store> _data;
   1.116 +    int _min;
   1.117 +    ItemIntMap &_iim;
   1.118 +    Compare _comp;
   1.119 +    int _num_items;
   1.120  
   1.121    public:
   1.122 -    ///Status of the nodes
   1.123 -    enum State {
   1.124 -      ///The node is in the heap
   1.125 -      IN_HEAP = 0,
   1.126 -      ///The node has never been in the heap
   1.127 -      PRE_HEAP = -1,
   1.128 -      ///The node was in the heap but it got out of it
   1.129 -      POST_HEAP = -2
   1.130 -    };
   1.131 +    /// \brief Constructor.
   1.132 +    ///
   1.133 +    /// Constructor.
   1.134 +    /// \param map A map that assigns \c int values to the items.
   1.135 +    /// It is used internally to handle the cross references.
   1.136 +    /// The assigned value must be \c PRE_HEAP (<tt>-1</tt>) for each item.
   1.137 +    explicit PairingHeap(ItemIntMap &map)
   1.138 +      : _min(0), _iim(map), _num_items(0) {}
   1.139  
   1.140 -    /// \brief The constructor
   1.141 +    /// \brief Constructor.
   1.142      ///
   1.143 -    /// \c _iimap should be given to the constructor, since it is
   1.144 -    ///   used internally to handle the cross references.
   1.145 -    explicit PairingHeap(ItemIntMap &_iimap)
   1.146 -      : minimum(0), iimap(_iimap), num_items(0) {}
   1.147 -
   1.148 -    /// \brief The constructor
   1.149 -    ///
   1.150 -    /// \c _iimap should be given to the constructor, since it is used
   1.151 -    /// internally to handle the cross references. \c _comp is an
   1.152 -    /// object for ordering of the priorities.
   1.153 -    PairingHeap(ItemIntMap &_iimap, const Compare &_comp)
   1.154 -      : minimum(0), iimap(_iimap), comp(_comp), num_items(0) {}
   1.155 +    /// Constructor.
   1.156 +    /// \param map A map that assigns \c int values to the items.
   1.157 +    /// It is used internally to handle the cross references.
   1.158 +    /// The assigned value must be \c PRE_HEAP (<tt>-1</tt>) for each item.
   1.159 +    /// \param comp The function object used for comparing the priorities.
   1.160 +    PairingHeap(ItemIntMap &map, const Compare &comp)
   1.161 +      : _min(0), _iim(map), _comp(comp), _num_items(0) {}
   1.162  
   1.163      /// \brief The number of items stored in the heap.
   1.164      ///
   1.165 -    /// Returns the number of items stored in the heap.
   1.166 -    int size() const { return num_items; }
   1.167 +    /// This function returns the number of items stored in the heap.
   1.168 +    int size() const { return _num_items; }
   1.169  
   1.170 -    /// \brief Checks if the heap stores no items.
   1.171 +    /// \brief Check if the heap is empty.
   1.172      ///
   1.173 -    ///   Returns \c true if and only if the heap stores no items.
   1.174 -    bool empty() const { return num_items==0; }
   1.175 +    /// This function returns \c true if the heap is empty.
   1.176 +    bool empty() const { return _num_items==0; }
   1.177  
   1.178 -    /// \brief Make empty this heap.
   1.179 +    /// \brief Make the heap empty.
   1.180      ///
   1.181 -    /// Make empty this heap. It does not change the cross reference
   1.182 -    /// map.  If you want to reuse a heap what is not surely empty you
   1.183 -    /// should first clear the heap and after that you should set the
   1.184 -    /// cross reference map for each item to \c PRE_HEAP.
   1.185 +    /// This functon makes the heap empty.
   1.186 +    /// It does not change the cross reference map. If you want to reuse
   1.187 +    /// a heap that is not surely empty, you should first clear it and
   1.188 +    /// then you should set the cross reference map to \c PRE_HEAP
   1.189 +    /// for each item.
   1.190      void clear() {
   1.191 -      container.clear();
   1.192 -      minimum = 0;
   1.193 -      num_items = 0;
   1.194 +      _data.clear();
   1.195 +      _min = 0;
   1.196 +      _num_items = 0;
   1.197      }
   1.198  
   1.199 -    /// \brief \c item gets to the heap with priority \c value independently
   1.200 -    /// if \c item was already there.
   1.201 +    /// \brief Set the priority of an item or insert it, if it is
   1.202 +    /// not stored in the heap.
   1.203      ///
   1.204 -    /// This method calls \ref push(\c item, \c value) if \c item is not
   1.205 -    /// stored in the heap and it calls \ref decrease(\c item, \c value) or
   1.206 -    /// \ref increase(\c item, \c value) otherwise.
   1.207 +    /// This method sets the priority of the given item if it is
   1.208 +    /// already stored in the heap. Otherwise it inserts the given
   1.209 +    /// item into the heap with the given priority.
   1.210 +    /// \param item The item.
   1.211 +    /// \param value The priority.
   1.212      void set (const Item& item, const Prio& value) {
   1.213 -      int i=iimap[item];
   1.214 -      if ( i>=0 && container[i].in ) {
   1.215 -        if ( comp(value, container[i].prio) ) decrease(item, value);
   1.216 -        if ( comp(container[i].prio, value) ) increase(item, value);
   1.217 +      int i=_iim[item];
   1.218 +      if ( i>=0 && _data[i].in ) {
   1.219 +        if ( _comp(value, _data[i].prio) ) decrease(item, value);
   1.220 +        if ( _comp(_data[i].prio, value) ) increase(item, value);
   1.221        } else push(item, value);
   1.222      }
   1.223  
   1.224 -    /// \brief Adds \c item to the heap with priority \c value.
   1.225 +    /// \brief Insert an item into the heap with the given priority.
   1.226      ///
   1.227 -    /// Adds \c item to the heap with priority \c value.
   1.228 -    /// \pre \c item must not be stored in the heap.
   1.229 +    /// This function inserts the given item into the heap with the
   1.230 +    /// given priority.
   1.231 +    /// \param item The item to insert.
   1.232 +    /// \param value The priority of the item.
   1.233 +    /// \pre \e item must not be stored in the heap.
   1.234      void push (const Item& item, const Prio& value) {
   1.235 -      int i=iimap[item];
   1.236 +      int i=_iim[item];
   1.237        if( i<0 ) {
   1.238 -        int s=container.size();
   1.239 -        iimap.set(item, s);
   1.240 +        int s=_data.size();
   1.241 +        _iim.set(item, s);
   1.242          store st;
   1.243          st.name=item;
   1.244 -        container.push_back(st);
   1.245 +        _data.push_back(st);
   1.246          i=s;
   1.247        } else {
   1.248 -        container[i].parent=container[i].child=-1;
   1.249 -        container[i].left_child=false;
   1.250 -        container[i].degree=0;
   1.251 -        container[i].in=true;
   1.252 +        _data[i].parent=_data[i].child=-1;
   1.253 +        _data[i].left_child=false;
   1.254 +        _data[i].degree=0;
   1.255 +        _data[i].in=true;
   1.256        }
   1.257  
   1.258 -      container[i].prio=value;
   1.259 +      _data[i].prio=value;
   1.260  
   1.261 -      if ( num_items!=0 ) {
   1.262 -        if ( comp( value, container[minimum].prio) ) {
   1.263 -          fuse(i,minimum);
   1.264 -          minimum=i;
   1.265 +      if ( _num_items!=0 ) {
   1.266 +        if ( _comp( value, _data[_min].prio) ) {
   1.267 +          fuse(i,_min);
   1.268 +          _min=i;
   1.269          }
   1.270 -        else fuse(minimum,i);
   1.271 +        else fuse(_min,i);
   1.272        }
   1.273 -      else minimum=i;
   1.274 +      else _min=i;
   1.275  
   1.276 -      ++num_items;
   1.277 +      ++_num_items;
   1.278      }
   1.279  
   1.280 -    /// \brief Returns the item with minimum priority relative to \c Compare.
   1.281 +    /// \brief Return the item having minimum priority.
   1.282      ///
   1.283 -    /// This method returns the item with minimum priority relative to \c
   1.284 -    /// Compare.
   1.285 -    /// \pre The heap must be nonempty.
   1.286 -    Item top() const { return container[minimum].name; }
   1.287 +    /// This function returns the item having minimum priority.
   1.288 +    /// \pre The heap must be non-empty.
   1.289 +    Item top() const { return _data[_min].name; }
   1.290  
   1.291 -    /// \brief Returns the minimum priority relative to \c Compare.
   1.292 +    /// \brief The minimum priority.
   1.293      ///
   1.294 -    /// It returns the minimum priority relative to \c Compare.
   1.295 -    /// \pre The heap must be nonempty.
   1.296 -    const Prio& prio() const { return container[minimum].prio; }
   1.297 +    /// This function returns the minimum priority.
   1.298 +    /// \pre The heap must be non-empty.
   1.299 +    const Prio& prio() const { return _data[_min].prio; }
   1.300  
   1.301 -    /// \brief Returns the priority of \c item.
   1.302 +    /// \brief The priority of the given item.
   1.303      ///
   1.304 -    /// It returns the priority of \c item.
   1.305 -    /// \pre \c item must be in the heap.
   1.306 +    /// This function returns the priority of the given item.
   1.307 +    /// \param item The item.
   1.308 +    /// \pre \e item must be in the heap.
   1.309      const Prio& operator[](const Item& item) const {
   1.310 -      return container[iimap[item]].prio;
   1.311 +      return _data[_iim[item]].prio;
   1.312      }
   1.313  
   1.314 -    /// \brief Deletes the item with minimum priority relative to \c Compare.
   1.315 +    /// \brief Remove the item having minimum priority.
   1.316      ///
   1.317 -    /// This method deletes the item with minimum priority relative to \c
   1.318 -    /// Compare from the heap.
   1.319 +    /// This function removes the item having minimum priority.
   1.320      /// \pre The heap must be non-empty.
   1.321      void pop() {
   1.322 -      int TreeArray[num_items];
   1.323 +      int TreeArray[_num_items];
   1.324        int i=0, num_child=0, child_right = 0;
   1.325 -      container[minimum].in=false;
   1.326 +      _data[_min].in=false;
   1.327  
   1.328 -      if( -1!=container[minimum].child ) {
   1.329 -        i=container[minimum].child;
   1.330 +      if( -1!=_data[_min].child ) {
   1.331 +        i=_data[_min].child;
   1.332          TreeArray[num_child] = i;
   1.333 -        container[i].parent = -1;
   1.334 -        container[minimum].child = -1;
   1.335 +        _data[i].parent = -1;
   1.336 +        _data[_min].child = -1;
   1.337  
   1.338          ++num_child;
   1.339          int ch=-1;
   1.340 -        while( container[i].child!=-1 ) {
   1.341 -          ch=container[i].child;
   1.342 -          if( container[ch].left_child && i==container[ch].parent ) {
   1.343 +        while( _data[i].child!=-1 ) {
   1.344 +          ch=_data[i].child;
   1.345 +          if( _data[ch].left_child && i==_data[ch].parent ) {
   1.346              i=ch;
   1.347              //break;
   1.348            } else {
   1.349 -            if( container[ch].left_child ) {
   1.350 -              child_right=container[ch].parent;
   1.351 -              container[ch].parent = i;
   1.352 -              --container[i].degree;
   1.353 +            if( _data[ch].left_child ) {
   1.354 +              child_right=_data[ch].parent;
   1.355 +              _data[ch].parent = i;
   1.356 +              --_data[i].degree;
   1.357              }
   1.358              else {
   1.359                child_right=ch;
   1.360 -              container[i].child=-1;
   1.361 -              container[i].degree=0;
   1.362 +              _data[i].child=-1;
   1.363 +              _data[i].degree=0;
   1.364              }
   1.365 -            container[child_right].parent = -1;
   1.366 +            _data[child_right].parent = -1;
   1.367              TreeArray[num_child] = child_right;
   1.368              i = child_right;
   1.369              ++num_child;
   1.370 @@ -239,8 +245,8 @@
   1.371  
   1.372          int other;
   1.373          for( i=0; i<num_child-1; i+=2 ) {
   1.374 -          if ( !comp(container[TreeArray[i]].prio,
   1.375 -                     container[TreeArray[i+1]].prio) ) {
   1.376 +          if ( !_comp(_data[TreeArray[i]].prio,
   1.377 +                     _data[TreeArray[i+1]].prio) ) {
   1.378              other=TreeArray[i];
   1.379              TreeArray[i]=TreeArray[i+1];
   1.380              TreeArray[i+1]=other;
   1.381 @@ -250,8 +256,8 @@
   1.382  
   1.383          i = (0==(num_child % 2)) ? num_child-2 : num_child-1;
   1.384          while(i>=2) {
   1.385 -          if ( comp(container[TreeArray[i]].prio,
   1.386 -                    container[TreeArray[i-2]].prio) ) {
   1.387 +          if ( _comp(_data[TreeArray[i]].prio,
   1.388 +                    _data[TreeArray[i-2]].prio) ) {
   1.389              other=TreeArray[i];
   1.390              TreeArray[i]=TreeArray[i-2];
   1.391              TreeArray[i-2]=other;
   1.392 @@ -259,88 +265,91 @@
   1.393            fuse( TreeArray[i-2], TreeArray[i] );
   1.394            i-=2;
   1.395          }
   1.396 -        minimum = TreeArray[0];
   1.397 +        _min = TreeArray[0];
   1.398        }
   1.399  
   1.400        if ( 0==num_child ) {
   1.401 -        minimum = container[minimum].child;
   1.402 +        _min = _data[_min].child;
   1.403        }
   1.404  
   1.405 -      if (minimum >= 0) container[minimum].left_child = false;
   1.406 +      if (_min >= 0) _data[_min].left_child = false;
   1.407  
   1.408 -      --num_items;
   1.409 +      --_num_items;
   1.410      }
   1.411  
   1.412 -    /// \brief Deletes \c item from the heap.
   1.413 +    /// \brief Remove the given item from the heap.
   1.414      ///
   1.415 -    /// This method deletes \c item from the heap, if \c item was already
   1.416 -    /// stored in the heap. It is quite inefficient in Pairing heaps.
   1.417 +    /// This function removes the given item from the heap if it is
   1.418 +    /// already stored.
   1.419 +    /// \param item The item to delete.
   1.420 +    /// \pre \e item must be in the heap.
   1.421      void erase (const Item& item) {
   1.422 -      int i=iimap[item];
   1.423 -      if ( i>=0 && container[i].in ) {
   1.424 -        decrease( item, container[minimum].prio-1 );
   1.425 +      int i=_iim[item];
   1.426 +      if ( i>=0 && _data[i].in ) {
   1.427 +        decrease( item, _data[_min].prio-1 );
   1.428          pop();
   1.429        }
   1.430      }
   1.431  
   1.432 -    /// \brief Decreases the priority of \c item to \c value.
   1.433 +    /// \brief Decrease the priority of an item to the given value.
   1.434      ///
   1.435 -    /// This method decreases the priority of \c item to \c value.
   1.436 -    /// \pre \c item must be stored in the heap with priority at least \c
   1.437 -    ///   value relative to \c Compare.
   1.438 +    /// This function decreases the priority of an item to the given value.
   1.439 +    /// \param item The item.
   1.440 +    /// \param value The priority.
   1.441 +    /// \pre \e item must be stored in the heap with priority at least \e value.
   1.442      void decrease (Item item, const Prio& value) {
   1.443 -      int i=iimap[item];
   1.444 -      container[i].prio=value;
   1.445 -      int p=container[i].parent;
   1.446 +      int i=_iim[item];
   1.447 +      _data[i].prio=value;
   1.448 +      int p=_data[i].parent;
   1.449  
   1.450 -      if( container[i].left_child && i!=container[p].child ) {
   1.451 -        p=container[p].parent;
   1.452 +      if( _data[i].left_child && i!=_data[p].child ) {
   1.453 +        p=_data[p].parent;
   1.454        }
   1.455  
   1.456 -      if ( p!=-1 && comp(value,container[p].prio) ) {
   1.457 +      if ( p!=-1 && _comp(value,_data[p].prio) ) {
   1.458          cut(i,p);
   1.459 -        if ( comp(container[minimum].prio,value) ) {
   1.460 -          fuse(minimum,i);
   1.461 +        if ( _comp(_data[_min].prio,value) ) {
   1.462 +          fuse(_min,i);
   1.463          } else {
   1.464 -          fuse(i,minimum);
   1.465 -          minimum=i;
   1.466 +          fuse(i,_min);
   1.467 +          _min=i;
   1.468          }
   1.469        }
   1.470      }
   1.471  
   1.472 -    /// \brief Increases the priority of \c item to \c value.
   1.473 +    /// \brief Increase the priority of an item to the given value.
   1.474      ///
   1.475 -    /// This method sets the priority of \c item to \c value. Though
   1.476 -    /// there is no precondition on the priority of \c item, this
   1.477 -    /// method should be used only if it is indeed necessary to increase
   1.478 -    /// (relative to \c Compare) the priority of \c item, because this
   1.479 -    /// method is inefficient.
   1.480 +    /// This function increases the priority of an item to the given value.
   1.481 +    /// \param item The item.
   1.482 +    /// \param value The priority.
   1.483 +    /// \pre \e item must be stored in the heap with priority at most \e value.
   1.484      void increase (Item item, const Prio& value) {
   1.485        erase(item);
   1.486        push(item,value);
   1.487      }
   1.488  
   1.489 -    /// \brief Returns if \c item is in, has already been in, or has never
   1.490 -    /// been in the heap.
   1.491 +    /// \brief Return the state of an item.
   1.492      ///
   1.493 -    /// This method returns PRE_HEAP if \c item has never been in the
   1.494 -    /// heap, IN_HEAP if it is in the heap at the moment, and POST_HEAP
   1.495 -    /// otherwise. In the latter case it is possible that \c item will
   1.496 -    /// get back to the heap again.
   1.497 +    /// This method returns \c PRE_HEAP if the given item has never
   1.498 +    /// been in the heap, \c IN_HEAP if it is in the heap at the moment,
   1.499 +    /// and \c POST_HEAP otherwise.
   1.500 +    /// In the latter case it is possible that the item will get back
   1.501 +    /// to the heap again.
   1.502 +    /// \param item The item.
   1.503      State state(const Item &item) const {
   1.504 -      int i=iimap[item];
   1.505 +      int i=_iim[item];
   1.506        if( i>=0 ) {
   1.507 -        if( container[i].in ) i=0;
   1.508 +        if( _data[i].in ) i=0;
   1.509          else i=-2;
   1.510        }
   1.511        return State(i);
   1.512      }
   1.513  
   1.514 -    /// \brief Sets the state of the \c item in the heap.
   1.515 +    /// \brief Set the state of an item in the heap.
   1.516      ///
   1.517 -    /// Sets the state of the \c item in the heap. It can be used to
   1.518 -    /// manually clear the heap when it is important to achive the
   1.519 -    /// better time complexity.
   1.520 +    /// This function sets the state of the given item in the heap.
   1.521 +    /// It can be used to manually clear the heap when it is important
   1.522 +    /// to achive better time complexity.
   1.523      /// \param i The item.
   1.524      /// \param st The state. It should not be \c IN_HEAP.
   1.525      void state(const Item& i, State st) {
   1.526 @@ -348,7 +357,7 @@
   1.527        case POST_HEAP:
   1.528        case PRE_HEAP:
   1.529          if (state(i) == IN_HEAP) erase(i);
   1.530 -        iimap[i]=st;
   1.531 +        _iim[i]=st;
   1.532          break;
   1.533        case IN_HEAP:
   1.534          break;
   1.535 @@ -359,95 +368,95 @@
   1.536  
   1.537      void cut(int a, int b) {
   1.538        int child_a;
   1.539 -      switch (container[a].degree) {
   1.540 +      switch (_data[a].degree) {
   1.541          case 2:
   1.542 -          child_a = container[container[a].child].parent;
   1.543 -          if( container[a].left_child ) {
   1.544 -            container[child_a].left_child=true;
   1.545 -            container[b].child=child_a;
   1.546 -            container[child_a].parent=container[a].parent;
   1.547 +          child_a = _data[_data[a].child].parent;
   1.548 +          if( _data[a].left_child ) {
   1.549 +            _data[child_a].left_child=true;
   1.550 +            _data[b].child=child_a;
   1.551 +            _data[child_a].parent=_data[a].parent;
   1.552            }
   1.553            else {
   1.554 -            container[child_a].left_child=false;
   1.555 -            container[child_a].parent=b;
   1.556 -            if( a!=container[b].child )
   1.557 -              container[container[b].child].parent=child_a;
   1.558 +            _data[child_a].left_child=false;
   1.559 +            _data[child_a].parent=b;
   1.560 +            if( a!=_data[b].child )
   1.561 +              _data[_data[b].child].parent=child_a;
   1.562              else
   1.563 -              container[b].child=child_a;
   1.564 +              _data[b].child=child_a;
   1.565            }
   1.566 -          --container[a].degree;
   1.567 -          container[container[a].child].parent=a;
   1.568 +          --_data[a].degree;
   1.569 +          _data[_data[a].child].parent=a;
   1.570            break;
   1.571  
   1.572          case 1:
   1.573 -          child_a = container[a].child;
   1.574 -          if( !container[child_a].left_child ) {
   1.575 -            --container[a].degree;
   1.576 -            if( container[a].left_child ) {
   1.577 -              container[child_a].left_child=true;
   1.578 -              container[child_a].parent=container[a].parent;
   1.579 -              container[b].child=child_a;
   1.580 +          child_a = _data[a].child;
   1.581 +          if( !_data[child_a].left_child ) {
   1.582 +            --_data[a].degree;
   1.583 +            if( _data[a].left_child ) {
   1.584 +              _data[child_a].left_child=true;
   1.585 +              _data[child_a].parent=_data[a].parent;
   1.586 +              _data[b].child=child_a;
   1.587              }
   1.588              else {
   1.589 -              container[child_a].left_child=false;
   1.590 -              container[child_a].parent=b;
   1.591 -              if( a!=container[b].child )
   1.592 -                container[container[b].child].parent=child_a;
   1.593 +              _data[child_a].left_child=false;
   1.594 +              _data[child_a].parent=b;
   1.595 +              if( a!=_data[b].child )
   1.596 +                _data[_data[b].child].parent=child_a;
   1.597                else
   1.598 -                container[b].child=child_a;
   1.599 +                _data[b].child=child_a;
   1.600              }
   1.601 -            container[a].child=-1;
   1.602 +            _data[a].child=-1;
   1.603            }
   1.604            else {
   1.605 -            --container[b].degree;
   1.606 -            if( container[a].left_child ) {
   1.607 -              container[b].child =
   1.608 -                (1==container[b].degree) ? container[a].parent : -1;
   1.609 +            --_data[b].degree;
   1.610 +            if( _data[a].left_child ) {
   1.611 +              _data[b].child =
   1.612 +                (1==_data[b].degree) ? _data[a].parent : -1;
   1.613              } else {
   1.614 -              if (1==container[b].degree)
   1.615 -                container[container[b].child].parent=b;
   1.616 +              if (1==_data[b].degree)
   1.617 +                _data[_data[b].child].parent=b;
   1.618                else
   1.619 -                container[b].child=-1;
   1.620 +                _data[b].child=-1;
   1.621              }
   1.622            }
   1.623            break;
   1.624  
   1.625          case 0:
   1.626 -          --container[b].degree;
   1.627 -          if( container[a].left_child ) {
   1.628 -            container[b].child =
   1.629 -              (0!=container[b].degree) ? container[a].parent : -1;
   1.630 +          --_data[b].degree;
   1.631 +          if( _data[a].left_child ) {
   1.632 +            _data[b].child =
   1.633 +              (0!=_data[b].degree) ? _data[a].parent : -1;
   1.634            } else {
   1.635 -            if( 0!=container[b].degree )
   1.636 -              container[container[b].child].parent=b;
   1.637 +            if( 0!=_data[b].degree )
   1.638 +              _data[_data[b].child].parent=b;
   1.639              else
   1.640 -              container[b].child=-1;
   1.641 +              _data[b].child=-1;
   1.642            }
   1.643            break;
   1.644        }
   1.645 -      container[a].parent=-1;
   1.646 -      container[a].left_child=false;
   1.647 +      _data[a].parent=-1;
   1.648 +      _data[a].left_child=false;
   1.649      }
   1.650  
   1.651      void fuse(int a, int b) {
   1.652 -      int child_a = container[a].child;
   1.653 -      int child_b = container[b].child;
   1.654 -      container[a].child=b;
   1.655 -      container[b].parent=a;
   1.656 -      container[b].left_child=true;
   1.657 +      int child_a = _data[a].child;
   1.658 +      int child_b = _data[b].child;
   1.659 +      _data[a].child=b;
   1.660 +      _data[b].parent=a;
   1.661 +      _data[b].left_child=true;
   1.662  
   1.663        if( -1!=child_a ) {
   1.664 -        container[b].child=child_a;
   1.665 -        container[child_a].parent=b;
   1.666 -        container[child_a].left_child=false;
   1.667 -        ++container[b].degree;
   1.668 +        _data[b].child=child_a;
   1.669 +        _data[child_a].parent=b;
   1.670 +        _data[child_a].left_child=false;
   1.671 +        ++_data[b].degree;
   1.672  
   1.673          if( -1!=child_b ) {
   1.674 -           container[b].child=child_b;
   1.675 -           container[child_b].parent=child_a;
   1.676 +           _data[b].child=child_b;
   1.677 +           _data[child_b].parent=child_a;
   1.678          }
   1.679        }
   1.680 -      else { ++container[a].degree; }
   1.681 +      else { ++_data[a].degree; }
   1.682      }
   1.683  
   1.684      class store {