/* -*- C++ -*-

  *

  * This file is a part of LEMON, a generic C++ optimization library

  *

  * Copyright (C) 2003-2010

  * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport

  * (Egervary Research Group on Combinatorial Optimization, EGRES).

  *

  * Permission to use, modify and distribute this software is granted

  * provided that this copyright notice appears in all copies. For

  * precise terms see the accompanying LICENSE file.

  *

  * This software is provided "AS IS" with no warranty of any kind,

  * express or implied, and with no claim as to its suitability for any

  * purpose.

  *

  */

 #ifndef LEMON_MAX_CARDINALITY_SEARCH_H

 #define LEMON_MAX_CARDINALITY_SEARCH_H

 /// \ingroup search

 /// \file 

 /// \brief Maximum cardinality search in undirected digraphs.

 #include <lemon/bin_heap.h>

 #include <lemon/bucket_heap.h>

 #include <lemon/error.h>

 #include <lemon/maps.h>

 #include <functional>

 namespace lemon {

   /// \brief Default traits class of MaxCardinalitySearch class.

   ///

   /// Default traits class of MaxCardinalitySearch class.

   /// \param Digraph Digraph type.

   /// \param CapacityMap Type of capacity map.

   template <typename GR, typename CAP>

   struct MaxCardinalitySearchDefaultTraits {

     /// The digraph type the algorithm runs on. 

     typedef GR Digraph;

     template <typename CM>

     struct CapMapSelector {

       typedef CM CapacityMap;

       static CapacityMap *createCapacityMap(const Digraph& g) {

 	return new CapacityMap(g);

       }

     };

     template <typename CM>

     struct CapMapSelector<ConstMap<CM, Const<int, 1> > > {

       typedef ConstMap<CM, Const<int, 1> > CapacityMap;

       static CapacityMap *createCapacityMap(const Digraph&) {

 	return new CapacityMap;

       }

     };

     /// \brief The type of the map that stores the arc capacities.

     ///

     /// The type of the map that stores the arc capacities.

     /// It must meet the \ref concepts::ReadMap "ReadMap" concept.

     typedef typename CapMapSelector<CAP>::CapacityMap CapacityMap;

     /// \brief The type of the capacity of the arcs.

     typedef typename CapacityMap::Value Value;

     /// \brief Instantiates a CapacityMap.

     ///

     /// This function instantiates a \ref CapacityMap.

     /// \param digraph is the digraph, to which we would like to define

     /// the CapacityMap.

     static CapacityMap *createCapacityMap(const Digraph& digraph) {

       return CapMapSelector<CapacityMap>::createCapacityMap(digraph);

     }

     /// \brief The cross reference type used by heap.

     ///

     /// The cross reference type used by heap.

     /// Usually it is \c Digraph::NodeMap<int>.

     typedef typename Digraph::template NodeMap<int> HeapCrossRef;

     /// \brief Instantiates a HeapCrossRef.

     ///

     /// This function instantiates a \ref HeapCrossRef. 

     /// \param digraph is the digraph, to which we would like to define the 

     /// HeapCrossRef.

     static HeapCrossRef *createHeapCrossRef(const Digraph &digraph) {

       return new HeapCrossRef(digraph);

     }

     template <typename CapacityMap>

     struct HeapSelector {

       template <typename Value, typename Ref>

       struct Selector { 

         typedef BinHeap<Value, Ref, std::greater<Value> > Heap;

       };

     };

     template <typename CapacityKey>

     struct HeapSelector<ConstMap<CapacityKey, Const<int, 1> > > {

       template <typename Value, typename Ref>

       struct Selector {

         typedef BucketHeap<Ref, false > Heap;

       };

     };

     /// \brief The heap type used by MaxCardinalitySearch algorithm.

     ///

     /// The heap type used by MaxCardinalitySearch algorithm. It should

     /// maximalize the priorities. The default heap type is

     /// the \ref BinHeap, but it is specialized when the

     /// CapacityMap is ConstMap<Digraph::Node, Const<int, 1> >

     /// to BucketHeap.

     ///

     /// \sa MaxCardinalitySearch

     typedef typename HeapSelector<CapacityMap>

     ::template Selector<Value, HeapCrossRef>

     ::Heap Heap;

     /// \brief Instantiates a Heap.

     ///

     /// This function instantiates a \ref Heap. 

     /// \param crossref The cross reference of the heap.

     static Heap *createHeap(HeapCrossRef& crossref) {

       return new Heap(crossref);

     }

     /// \brief The type of the map that stores whether a node is processed.

     ///

     /// The type of the map that stores whether a node is processed.

     /// It must meet the \ref concepts::WriteMap "WriteMap" concept.

     /// By default it is a NullMap.

     typedef NullMap<typename Digraph::Node, bool> ProcessedMap;

     /// \brief Instantiates a ProcessedMap.

     ///

     /// This function instantiates a \ref ProcessedMap. 

     /// \param digraph is the digraph, to which

     /// we would like to define the \ref ProcessedMap

 #ifdef DOXYGEN

     static ProcessedMap *createProcessedMap(const Digraph &digraph)

 #else

     static ProcessedMap *createProcessedMap(const Digraph &)

 #endif

     {

       return new ProcessedMap();

     }

     /// \brief The type of the map that stores the cardinalities of the nodes.

     /// 

     /// The type of the map that stores the cardinalities of the nodes.

     /// It must meet the \ref concepts::WriteMap "WriteMap" concept.

     typedef typename Digraph::template NodeMap<Value> CardinalityMap;

     /// \brief Instantiates a CardinalityMap.

     ///

     /// This function instantiates a \ref CardinalityMap. 

     /// \param digraph is the digraph, to which we would like to define the \ref 

     /// CardinalityMap

     static CardinalityMap *createCardinalityMap(const Digraph &digraph) {

       return new CardinalityMap(digraph);

     }

   };

   /// \ingroup search

   ///

   /// \brief Maximum Cardinality Search algorithm class.

   ///

   /// This class provides an efficient implementation of Maximum Cardinality 

   /// Search algorithm. The maximum cardinality search first chooses any 

   /// node of the digraph. Then every time it chooses one unprocessed node

   /// with maximum cardinality, i.e the sum of capacities on out arcs to the nodes

   /// which were previusly processed.

   /// If there is a cut in the digraph the algorithm should choose

   /// again any unprocessed node of the digraph.

   /// The arc capacities are passed to the algorithm using a

   /// \ref concepts::ReadMap "ReadMap", so it is easy to change it to any 

   /// kind of capacity.

   ///

   /// The type of the capacity is determined by the \ref 

   /// concepts::ReadMap::Value "Value" of the capacity map.

   ///

   /// It is also possible to change the underlying priority heap.

   ///

   ///

   /// \param GR The digraph type the algorithm runs on. The value of

   /// Digraph is not used directly by the search algorithm, it 

   /// is only passed to \ref MaxCardinalitySearchDefaultTraits.

   /// \param CAP This read-only ArcMap determines the capacities of 

   /// the arcs. It is read once for each arc, so the map may involve in

   /// relatively time consuming process to compute the arc capacity if

   /// it is necessary. The default map type is \ref

   /// ConstMap "ConstMap<concepts::Digraph::Arc, Const<int,1> >". The value

   /// of CapacityMap is not used directly by search algorithm, it is only 

   /// passed to \ref MaxCardinalitySearchDefaultTraits.  

   /// \param TR Traits class to set various data types used by the 

   /// algorithm.  The default traits class is 

   /// \ref MaxCardinalitySearchDefaultTraits 

   /// "MaxCardinalitySearchDefaultTraits<GR, CAP>".  

   /// See \ref MaxCardinalitySearchDefaultTraits 

   /// for the documentation of a MaxCardinalitySearch traits class.

 #ifdef DOXYGEN

   template <typename GR, typename CAP, typename TR>

 #else

   template <typename GR, typename CAP = 

 	    ConstMap<typename GR::Arc, Const<int,1> >,

 	    typename TR = 

             MaxCardinalitySearchDefaultTraits<GR, CAP> >

 #endif

   class MaxCardinalitySearch {

   public:

     typedef TR Traits;

     ///The type of the underlying digraph.

     typedef typename Traits::Digraph Digraph;

     ///The type of the capacity of the arcs.

     typedef typename Traits::CapacityMap::Value Value;

     ///The type of the map that stores the arc capacities.

     typedef typename Traits::CapacityMap CapacityMap;

     ///The type of the map indicating if a node is processed.

     typedef typename Traits::ProcessedMap ProcessedMap;

     ///The type of the map that stores the cardinalities of the nodes.

     typedef typename Traits::CardinalityMap CardinalityMap;

     ///The cross reference type used for the current heap.

     typedef typename Traits::HeapCrossRef HeapCrossRef;

     ///The heap type used by the algorithm. It maximizes the priorities.

     typedef typename Traits::Heap Heap;

   private:

     // Pointer to the underlying digraph.

     const Digraph *_graph;

     // Pointer to the capacity map

     const CapacityMap *_capacity;

     // Indicates if \ref _capacity is locally allocated (\c true) or not.

     bool local_capacity;

     // Pointer to the map of cardinality.

     CardinalityMap *_cardinality;

     // Indicates if \ref _cardinality is locally allocated (\c true) or not.

     bool local_cardinality;

     // Pointer to the map of processed status of the nodes.

     ProcessedMap *_processed;

     // Indicates if \ref _processed is locally allocated (\c true) or not.

     bool local_processed;

     // Pointer to the heap cross references.

     HeapCrossRef *_heap_cross_ref;

     // Indicates if \ref _heap_cross_ref is locally allocated (\c true) or not.

     bool local_heap_cross_ref;

     // Pointer to the heap.

     Heap *_heap;

     // Indicates if \ref _heap is locally allocated (\c true) or not.

     bool local_heap;

   public :

     typedef MaxCardinalitySearch Create;

     ///\name Named template parameters

     ///@{

     template <class T>

     struct DefCapacityMapTraits : public Traits {

       typedef T CapacityMap;

       static CapacityMap *createCapacityMap(const Digraph &) {

        	LEMON_ASSERT(false,"Uninitialized parameter.");

 	return 0;

       }

     };

     /// \brief \ref named-templ-param "Named parameter" for setting 

     /// CapacityMap type

     ///

     /// \ref named-templ-param "Named parameter" for setting CapacityMap type

     /// for the algorithm.

     template <class T>

     struct SetCapacityMap 

       : public MaxCardinalitySearch<Digraph, CapacityMap, 

                                     DefCapacityMapTraits<T> > { 

       typedef MaxCardinalitySearch<Digraph, CapacityMap, 

                                    DefCapacityMapTraits<T> > Create;

     };

     template <class T>

     struct DefCardinalityMapTraits : public Traits {

       typedef T CardinalityMap;

       static CardinalityMap *createCardinalityMap(const Digraph &) 

       {

 	LEMON_ASSERT(false,"Uninitialized parameter.");

 	return 0;

       }

     };

     /// \brief \ref named-templ-param "Named parameter" for setting 

     /// CardinalityMap type

     ///

     /// \ref named-templ-param "Named parameter" for setting CardinalityMap 

     /// type for the algorithm.

     template <class T>

     struct SetCardinalityMap 

       : public MaxCardinalitySearch<Digraph, CapacityMap, 

                                     DefCardinalityMapTraits<T> > { 

       typedef MaxCardinalitySearch<Digraph, CapacityMap, 

                                    DefCardinalityMapTraits<T> > Create;

     };

     template <class T>

     struct DefProcessedMapTraits : public Traits {

       typedef T ProcessedMap;

       static ProcessedMap *createProcessedMap(const Digraph &) {

        	LEMON_ASSERT(false,"Uninitialized parameter.");

 	return 0;

       }

     };

     /// \brief \ref named-templ-param "Named parameter" for setting 

     /// ProcessedMap type

     ///

     /// \ref named-templ-param "Named parameter" for setting ProcessedMap type

     /// for the algorithm.

     template <class T>

     struct SetProcessedMap 

       : public MaxCardinalitySearch<Digraph, CapacityMap, 

                                     DefProcessedMapTraits<T> > { 

       typedef MaxCardinalitySearch<Digraph, CapacityMap, 

                                    DefProcessedMapTraits<T> > Create;

     };

     template <class H, class CR>

     struct DefHeapTraits : public Traits {

       typedef CR HeapCrossRef;

       typedef H Heap;

       static HeapCrossRef *createHeapCrossRef(const Digraph &) {

      	LEMON_ASSERT(false,"Uninitialized parameter.");

 	return 0;

       }

       static Heap *createHeap(HeapCrossRef &) {

        	LEMON_ASSERT(false,"Uninitialized parameter.");

 	return 0;

       }

     };

     /// \brief \ref named-templ-param "Named parameter" for setting heap 

     /// and cross reference type

     ///

     /// \ref named-templ-param "Named parameter" for setting heap and cross 

     /// reference type for the algorithm.

     template <class H, class CR = typename Digraph::template NodeMap<int> >

     struct SetHeap

       : public MaxCardinalitySearch<Digraph, CapacityMap, 

                                     DefHeapTraits<H, CR> > { 

       typedef MaxCardinalitySearch< Digraph, CapacityMap, 

                                     DefHeapTraits<H, CR> > Create;

     };

     template <class H, class CR>

     struct DefStandardHeapTraits : public Traits {

       typedef CR HeapCrossRef;

       typedef H Heap;

       static HeapCrossRef *createHeapCrossRef(const Digraph &digraph) {

 	return new HeapCrossRef(digraph);

       }

       static Heap *createHeap(HeapCrossRef &crossref) {

 	return new Heap(crossref);

       }

     };

     /// \brief \ref named-templ-param "Named parameter" for setting heap and 

     /// cross reference type with automatic allocation

     ///

     /// \ref named-templ-param "Named parameter" for setting heap and cross 

     /// reference type. It can allocate the heap and the cross reference 

     /// object if the cross reference's constructor waits for the digraph as 

     /// parameter and the heap's constructor waits for the cross reference.

     template <class H, class CR = typename Digraph::template NodeMap<int> >

     struct SetStandardHeap

       : public MaxCardinalitySearch<Digraph, CapacityMap, 

                                     DefStandardHeapTraits<H, CR> > { 

       typedef MaxCardinalitySearch<Digraph, CapacityMap, 

                                    DefStandardHeapTraits<H, CR> > 

       Create;

     };

     ///@}

   protected:

     MaxCardinalitySearch() {}

   public:      

     /// \brief Constructor.

     ///

     ///\param digraph the digraph the algorithm will run on.

     ///\param capacity the capacity map used by the algorithm.

     ///When no capacity map given, a constant 1 capacity map will

     ///be allocated.

 #ifdef DOXYGEN

     MaxCardinalitySearch(const Digraph& digraph,

 			 const CapacityMap& capacity=0 ) :

 #else

     MaxCardinalitySearch(const Digraph& digraph,

 			 const CapacityMap& capacity=*static_cast<const CapacityMap*>(0) ) :

 #endif

       _graph(&digraph),

       _capacity(&capacity), local_capacity(false),

       _cardinality(0), local_cardinality(false),

       _processed(0), local_processed(false),

       _heap_cross_ref(0), local_heap_cross_ref(false),

       _heap(0), local_heap(false)

     { }

     /// \brief Destructor.

     ~MaxCardinalitySearch() {

       if(local_capacity) delete _capacity;

       if(local_cardinality) delete _cardinality;

       if(local_processed) delete _processed;

       if(local_heap_cross_ref) delete _heap_cross_ref;

       if(local_heap) delete _heap;

     }

     /// \brief Sets the capacity map.

     ///

     /// Sets the capacity map.

     /// \return <tt> (*this) </tt>

     MaxCardinalitySearch &capacityMap(const CapacityMap &m) {

       if (local_capacity) {

 	delete _capacity;

 	local_capacity=false;

       }

       _capacity=&m;

       return *this;

     }

     /// \brief Returns a const reference to the capacity map.

     ///

     /// Returns a const reference to the capacity map used by

     /// the algorithm.

     const CapacityMap &capacityMap() const {

       return *_capacity;

     }

     /// \brief Sets the map storing the cardinalities calculated by the 

     /// algorithm.

     ///

     /// Sets the map storing the cardinalities calculated by the algorithm.

     /// If you don't use this function before calling \ref run(),

     /// it will allocate one. The destuctor deallocates this

     /// automatically allocated map, of course.

     /// \return <tt> (*this) </tt>

     MaxCardinalitySearch &cardinalityMap(CardinalityMap &m) {

       if(local_cardinality) {

 	delete _cardinality;

 	local_cardinality=false;

       }

       _cardinality = &m;

       return *this;

     }

     /// \brief Sets the map storing the processed nodes.

     ///

     /// Sets the map storing the processed nodes.

     /// If you don't use this function before calling \ref run(),

     /// it will allocate one. The destuctor deallocates this

     /// automatically allocated map, of course.

     /// \return <tt> (*this) </tt>

     MaxCardinalitySearch &processedMap(ProcessedMap &m) 

     {

       if(local_processed) {

 	delete _processed;

 	local_processed=false;

       }

       _processed = &m;

       return *this;

     }

     /// \brief Returns a const reference to the cardinality map.

     ///

     /// Returns a const reference to the cardinality map used by

     /// the algorithm.

     const ProcessedMap &processedMap() const {

       return *_processed;

     }

     /// \brief Sets the heap and the cross reference used by algorithm.

     ///

     /// Sets the heap and the cross reference used by algorithm.

     /// If you don't use this function before calling \ref run(),

     /// it will allocate one. The destuctor deallocates this

     /// automatically allocated map, of course.

     /// \return <tt> (*this) </tt>

     MaxCardinalitySearch &heap(Heap& hp, HeapCrossRef &cr) {

       if(local_heap_cross_ref) {

 	delete _heap_cross_ref;

 	local_heap_cross_ref = false;

       }

       _heap_cross_ref = &cr;

       if(local_heap) {

 	delete _heap;

 	local_heap = false;

       }

       _heap = &hp;

       return *this;

     }

     /// \brief Returns a const reference to the heap.

     ///

     /// Returns a const reference to the heap used by

     /// the algorithm.

     const Heap &heap() const {

       return *_heap;

     }

     /// \brief Returns a const reference to the cross reference.

     ///

     /// Returns a const reference to the cross reference

     /// of the heap.

     const HeapCrossRef &heapCrossRef() const {

       return *_heap_cross_ref;

     }

   private:

     typedef typename Digraph::Node Node;

     typedef typename Digraph::NodeIt NodeIt;

     typedef typename Digraph::Arc Arc;

     typedef typename Digraph::InArcIt InArcIt;

     void create_maps() {

       if(!_capacity) {

 	local_capacity = true;

 	_capacity = Traits::createCapacityMap(*_graph);

       }

       if(!_cardinality) {

 	local_cardinality = true;

 	_cardinality = Traits::createCardinalityMap(*_graph);

       }

       if(!_processed) {

 	local_processed = true;

 	_processed = Traits::createProcessedMap(*_graph);

       }

       if (!_heap_cross_ref) {

 	local_heap_cross_ref = true;

 	_heap_cross_ref = Traits::createHeapCrossRef(*_graph);

       }

       if (!_heap) {

 	local_heap = true;

 	_heap = Traits::createHeap(*_heap_cross_ref);

       }

     }

     void finalizeNodeData(Node node, Value capacity) {

       _processed->set(node, true);

       _cardinality->set(node, capacity);

     }

   public:

     /// \name Execution control

     /// The simplest way to execute the algorithm is to use

     /// one of the member functions called \ref run().

     /// \n

     /// If you need more control on the execution,

     /// first you must call \ref init(), then you can add several source nodes

     /// with \ref addSource().

     /// Finally \ref start() will perform the computation.

     ///@{

     /// \brief Initializes the internal data structures.

     ///

     /// Initializes the internal data structures, and clears the heap.

     void init() {

       create_maps();

       _heap->clear();

       for (NodeIt it(*_graph) ; it != INVALID ; ++it) {

 	_processed->set(it, false);

 	_heap_cross_ref->set(it, Heap::PRE_HEAP);

       }

     }

     /// \brief Adds a new source node.

     /// 

     /// Adds a new source node to the priority heap.

     ///

     /// It checks if the node has not yet been added to the heap.

     void addSource(Node source, Value capacity = 0) {

       if(_heap->state(source) == Heap::PRE_HEAP) {

 	_heap->push(source, capacity);

       } 

     }

     /// \brief Processes the next node in the priority heap

     ///

     /// Processes the next node in the priority heap.

     ///

     /// \return The processed node.

     ///

     /// \warning The priority heap must not be empty!

     Node processNextNode() {

       Node node = _heap->top(); 

       finalizeNodeData(node, _heap->prio());

       _heap->pop();

       for (InArcIt it(*_graph, node); it != INVALID; ++it) {

 	Node source = _graph->source(it);

 	switch (_heap->state(source)) {

 	case Heap::PRE_HEAP:

 	  _heap->push(source, (*_capacity)[it]);

 	  break;

 	case Heap::IN_HEAP:

 	  _heap->decrease(source, (*_heap)[source] + (*_capacity)[it]);

 	  break;

 	case Heap::POST_HEAP:

 	  break;

 	}

       }

       return node;

     }

     /// \brief Next node to be processed.

     ///

     /// Next node to be processed.

     ///

     /// \return The next node to be processed or INVALID if the 

     /// priority heap is empty.

     Node nextNode() { 

       return !_heap->empty() ? _heap->top() : INVALID;

     }

     /// \brief Returns \c false if there are nodes

     /// to be processed in the priority heap

     ///

     /// Returns \c false if there are nodes

     /// to be processed in the priority heap

     bool emptyQueue() { return _heap->empty(); }

     /// \brief Returns the number of the nodes to be processed 

     /// in the priority heap

     ///

     /// Returns the number of the nodes to be processed in the priority heap

     int emptySize() { return _heap->size(); }

     /// \brief Executes the algorithm.

     ///

     /// Executes the algorithm.

     ///

     ///\pre init() must be called and at least one node should be added

     /// with addSource() before using this function.

     ///

     /// This method runs the Maximum Cardinality Search algorithm from the 

     /// source node(s).

     void start() {

       while ( !_heap->empty() ) processNextNode();

     }

     /// \brief Executes the algorithm until \c dest is reached.

     ///

     /// Executes the algorithm until \c dest is reached.

     ///

     /// \pre init() must be called and at least one node should be added

     /// with addSource() before using this function.

     ///

     /// This method runs the %MaxCardinalitySearch algorithm from the source 

     /// nodes.

     void start(Node dest) {

       while ( !_heap->empty() && _heap->top()!=dest ) processNextNode();

       if ( !_heap->empty() ) finalizeNodeData(_heap->top(), _heap->prio());

     }

     /// \brief Executes the algorithm until a condition is met.

     ///

     /// Executes the algorithm until a condition is met.

     ///

     /// \pre init() must be called and at least one node should be added

     /// with addSource() before using this function.

     ///

     /// \param nm must be a bool (or convertible) node map. The algorithm

     /// will stop when it reaches a node \c v with <tt>nm[v]==true</tt>.

     template <typename NodeBoolMap>

     void start(const NodeBoolMap &nm) {

       while ( !_heap->empty() && !nm[_heap->top()] ) processNextNode();

       if ( !_heap->empty() ) finalizeNodeData(_heap->top(),_heap->prio());

     }

     /// \brief Runs the maximum cardinality search algorithm from node \c s.

     ///

     /// This method runs the %MaxCardinalitySearch algorithm from a root 

     /// node \c s.

     ///

     ///\note d.run(s) is just a shortcut of the following code.

     ///\code

     ///  d.init();

     ///  d.addSource(s);

     ///  d.start();

     ///\endcode

     void run(Node s) {

       init();

       addSource(s);

       start();

     }

     /// \brief Runs the maximum cardinality search algorithm for the 

     /// whole digraph.

     ///

     /// This method runs the %MaxCardinalitySearch algorithm from all 

     /// unprocessed node of the digraph.

     ///

     ///\note d.run(s) is just a shortcut of the following code.

     ///\code

     ///  d.init();

     ///  for (NodeIt it(digraph); it != INVALID; ++it) {

     ///    if (!d.reached(it)) {

     ///      d.addSource(s);

     ///      d.start();

     ///    }

     ///  }

     ///\endcode

     void run() {

       init();

       for (NodeIt it(*_graph); it != INVALID; ++it) {

         if (!reached(it)) {

           addSource(it);

           start();

         }

       }

     }

     ///@}

     /// \name Query Functions

     /// The results of the maximum cardinality search algorithm can be 

     /// obtained using these functions.

     /// \n

     /// Before the use of these functions, either run() or start() must be 

     /// called.

     ///@{

     /// \brief The cardinality of a node.

     ///

     /// Returns the cardinality of a node.

     /// \pre \ref run() must be called before using this function.

     /// \warning If node \c v in unreachable from the root the return value

     /// of this funcion is undefined.

     Value cardinality(Node node) const { return (*_cardinality)[node]; }

     /// \brief The current cardinality of a node.

     ///

     /// Returns the current cardinality of a node.

     /// \pre the given node should be reached but not processed

     Value currentCardinality(Node node) const { return (*_heap)[node]; }

     /// \brief Returns a reference to the NodeMap of cardinalities.

     ///

     /// Returns a reference to the NodeMap of cardinalities. \pre \ref run() 

     /// must be called before using this function.

     const CardinalityMap &cardinalityMap() const { return *_cardinality;}

     /// \brief Checks if a node is reachable from the root.

     ///

     /// Returns \c true if \c v is reachable from the root.

     /// \warning The source nodes are initated as unreached.

     /// \pre \ref run() must be called before using this function.

     bool reached(Node v) { return (*_heap_cross_ref)[v] != Heap::PRE_HEAP; }

     /// \brief Checks if a node is processed.

     ///

     /// Returns \c true if \c v is processed, i.e. the shortest

     /// path to \c v has already found.

     /// \pre \ref run() must be called before using this function.

     bool processed(Node v) { return (*_heap_cross_ref)[v] == Heap::POST_HEAP; }

     ///@}

   };

 }

 #endif