kpeter@696: /* -*- C++ -*-
kpeter@696:  *
kpeter@696:  * This file is a part of LEMON, a generic C++ optimization library
kpeter@696:  *
kpeter@696:  * Copyright (C) 2003-2008
kpeter@696:  * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
kpeter@696:  * (Egervary Research Group on Combinatorial Optimization, EGRES).
kpeter@696:  *
kpeter@696:  * Permission to use, modify and distribute this software is granted
kpeter@696:  * provided that this copyright notice appears in all copies. For
kpeter@696:  * precise terms see the accompanying LICENSE file.
kpeter@696:  *
kpeter@696:  * This software is provided "AS IS" with no warranty of any kind,
kpeter@696:  * express or implied, and with no claim as to its suitability for any
kpeter@696:  * purpose.
kpeter@696:  *
kpeter@696:  */
kpeter@696: 
kpeter@696: #ifndef LEMON_BELMANN_FORD_H
kpeter@696: #define LEMON_BELMANN_FORD_H
kpeter@696: 
kpeter@696: /// \ingroup shortest_path
kpeter@696: /// \file
kpeter@696: /// \brief Bellman-Ford algorithm.
kpeter@696: ///
kpeter@696: 
kpeter@696: #include <lemon/bits/path_dump.h>
kpeter@696: #include <lemon/core.h>
kpeter@696: #include <lemon/error.h>
kpeter@696: #include <lemon/maps.h>
kpeter@696: 
kpeter@696: #include <limits>
kpeter@696: 
kpeter@696: namespace lemon {
kpeter@696: 
kpeter@696:   /// \brief Default OperationTraits for the BellmanFord algorithm class.
kpeter@696:   ///  
kpeter@696:   /// It defines all computational operations and constants which are
kpeter@696:   /// used in the Bellman-Ford algorithm. The default implementation
kpeter@696:   /// is based on the numeric_limits class. If the numeric type does not
kpeter@696:   /// have infinity value then the maximum value is used as extremal
kpeter@696:   /// infinity value.
kpeter@696:   template <
kpeter@696:     typename Value, 
kpeter@696:     bool has_infinity = std::numeric_limits<Value>::has_infinity>
kpeter@696:   struct BellmanFordDefaultOperationTraits {
kpeter@696:     /// \brief Gives back the zero value of the type.
kpeter@696:     static Value zero() {
kpeter@696:       return static_cast<Value>(0);
kpeter@696:     }
kpeter@696:     /// \brief Gives back the positive infinity value of the type.
kpeter@696:     static Value infinity() {
kpeter@696:       return std::numeric_limits<Value>::infinity();
kpeter@696:     }
kpeter@696:     /// \brief Gives back the sum of the given two elements.
kpeter@696:     static Value plus(const Value& left, const Value& right) {
kpeter@696:       return left + right;
kpeter@696:     }
kpeter@696:     /// \brief Gives back true only if the first value less than the second.
kpeter@696:     static bool less(const Value& left, const Value& right) {
kpeter@696:       return left < right;
kpeter@696:     }
kpeter@696:   };
kpeter@696: 
kpeter@696:   template <typename Value>
kpeter@696:   struct BellmanFordDefaultOperationTraits<Value, false> {
kpeter@696:     static Value zero() {
kpeter@696:       return static_cast<Value>(0);
kpeter@696:     }
kpeter@696:     static Value infinity() {
kpeter@696:       return std::numeric_limits<Value>::max();
kpeter@696:     }
kpeter@696:     static Value plus(const Value& left, const Value& right) {
kpeter@696:       if (left == infinity() || right == infinity()) return infinity();
kpeter@696:       return left + right;
kpeter@696:     }
kpeter@696:     static bool less(const Value& left, const Value& right) {
kpeter@696:       return left < right;
kpeter@696:     }
kpeter@696:   };
kpeter@696:   
kpeter@696:   /// \brief Default traits class of BellmanFord class.
kpeter@696:   ///
kpeter@696:   /// Default traits class of BellmanFord class.
kpeter@696:   /// \param _Digraph Digraph type.
kpeter@696:   /// \param _LegthMap Type of length map.
kpeter@696:   template<class _Digraph, class _LengthMap>
kpeter@696:   struct BellmanFordDefaultTraits {
kpeter@696:     /// The digraph type the algorithm runs on. 
kpeter@696:     typedef _Digraph Digraph;
kpeter@696: 
kpeter@696:     /// \brief The type of the map that stores the arc lengths.
kpeter@696:     ///
kpeter@696:     /// The type of the map that stores the arc lengths.
kpeter@696:     /// It must meet the \ref concepts::ReadMap "ReadMap" concept.
kpeter@696:     typedef _LengthMap LengthMap;
kpeter@696: 
kpeter@696:     // The type of the length of the arcs.
kpeter@696:     typedef typename _LengthMap::Value Value;
kpeter@696: 
kpeter@696:     /// \brief Operation traits for Bellman-Ford algorithm.
kpeter@696:     ///
kpeter@696:     /// It defines the infinity type on the given Value type
kpeter@696:     /// and the used operation.
kpeter@696:     /// \see BellmanFordDefaultOperationTraits
kpeter@696:     typedef BellmanFordDefaultOperationTraits<Value> OperationTraits;
kpeter@696:  
kpeter@696:     /// \brief The type of the map that stores the last arcs of the 
kpeter@696:     /// shortest paths.
kpeter@696:     /// 
kpeter@696:     /// The type of the map that stores the last
kpeter@696:     /// arcs of the shortest paths.
kpeter@696:     /// It must meet the \ref concepts::WriteMap "WriteMap" concept.
kpeter@696:     ///
kpeter@696:     typedef typename Digraph::template NodeMap<typename _Digraph::Arc> PredMap;
kpeter@696: 
kpeter@696:     /// \brief Instantiates a PredMap.
kpeter@696:     /// 
kpeter@696:     /// This function instantiates a \ref PredMap. 
kpeter@696:     /// \param digraph is the digraph, to which we would like to define the PredMap.
kpeter@696:     static PredMap *createPredMap(const _Digraph& digraph) {
kpeter@696:       return new PredMap(digraph);
kpeter@696:     }
kpeter@696: 
kpeter@696:     /// \brief The type of the map that stores the dists of the nodes.
kpeter@696:     ///
kpeter@696:     /// The type of the map that stores the dists of the nodes.
kpeter@696:     /// It must meet the \ref concepts::WriteMap "WriteMap" concept.
kpeter@696:     ///
kpeter@696:     typedef typename Digraph::template NodeMap<typename _LengthMap::Value> 
kpeter@696:     DistMap;
kpeter@696: 
kpeter@696:     /// \brief Instantiates a DistMap.
kpeter@696:     ///
kpeter@696:     /// This function instantiates a \ref DistMap. 
kpeter@696:     /// \param digraph is the digraph, to which we would like to define the 
kpeter@696:     /// \ref DistMap
kpeter@696:     static DistMap *createDistMap(const _Digraph& digraph) {
kpeter@696:       return new DistMap(digraph);
kpeter@696:     }
kpeter@696: 
kpeter@696:   };
kpeter@696:   
kpeter@696:   /// \brief %BellmanFord algorithm class.
kpeter@696:   ///
kpeter@696:   /// \ingroup shortest_path
kpeter@696:   /// This class provides an efficient implementation of \c Bellman-Ford 
kpeter@696:   /// algorithm. The arc lengths are passed to the algorithm using a
kpeter@696:   /// \ref concepts::ReadMap "ReadMap", so it is easy to change it to any 
kpeter@696:   /// kind of length.
kpeter@696:   ///
kpeter@696:   /// The Bellman-Ford algorithm solves the shortest path from one node
kpeter@696:   /// problem when the arcs can have negative length but the digraph should
kpeter@696:   /// not contain cycles with negative sum of length. If we can assume
kpeter@696:   /// that all arc is non-negative in the digraph then the dijkstra algorithm
kpeter@696:   /// should be used rather.
kpeter@696:   ///
kpeter@696:   /// The maximal time complexity of the algorithm is \f$ O(ne) \f$.
kpeter@696:   ///
kpeter@696:   /// The type of the length is determined by the
kpeter@696:   /// \ref concepts::ReadMap::Value "Value" of the length map.
kpeter@696:   ///
kpeter@696:   /// \param _Digraph The digraph type the algorithm runs on. The default value
kpeter@696:   /// is \ref ListDigraph. The value of _Digraph is not used directly by
kpeter@696:   /// BellmanFord, it is only passed to \ref BellmanFordDefaultTraits.
kpeter@696:   /// \param _LengthMap This read-only ArcMap determines the lengths of the
kpeter@696:   /// arcs. The default map type is \ref concepts::Digraph::ArcMap 
kpeter@696:   /// "Digraph::ArcMap<int>".  The value of _LengthMap is not used directly 
kpeter@696:   /// by BellmanFord, it is only passed to \ref BellmanFordDefaultTraits.  
kpeter@696:   /// \param _Traits Traits class to set various data types used by the 
kpeter@696:   /// algorithm.  The default traits class is \ref BellmanFordDefaultTraits
kpeter@696:   /// "BellmanFordDefaultTraits<_Digraph,_LengthMap>".  See \ref
kpeter@696:   /// BellmanFordDefaultTraits for the documentation of a BellmanFord traits
kpeter@696:   /// class.
kpeter@696: #ifdef DOXYGEN
kpeter@696:   template <typename _Digraph, typename _LengthMap, typename _Traits>
kpeter@696: #else
kpeter@696:   template <typename _Digraph,
kpeter@696: 	    typename _LengthMap=typename _Digraph::template ArcMap<int>,
kpeter@696: 	    typename _Traits=BellmanFordDefaultTraits<_Digraph,_LengthMap> >
kpeter@696: #endif
kpeter@696:   class BellmanFord {
kpeter@696:   public:
kpeter@696: 
kpeter@696:     typedef _Traits Traits;
kpeter@696:     ///The type of the underlying digraph.
kpeter@696:     typedef typename _Traits::Digraph Digraph;
kpeter@696: 
kpeter@696:     typedef typename Digraph::Node Node;
kpeter@696:     typedef typename Digraph::NodeIt NodeIt;
kpeter@696:     typedef typename Digraph::Arc Arc;
kpeter@696:     typedef typename Digraph::OutArcIt OutArcIt;
kpeter@696:     
kpeter@696:     /// \brief The type of the length of the arcs.
kpeter@696:     typedef typename _Traits::LengthMap::Value Value;
kpeter@696:     /// \brief The type of the map that stores the arc lengths.
kpeter@696:     typedef typename _Traits::LengthMap LengthMap;
kpeter@696:     /// \brief The type of the map that stores the last
kpeter@696:     /// arcs of the shortest paths.
kpeter@696:     typedef typename _Traits::PredMap PredMap;
kpeter@696:     /// \brief The type of the map that stores the dists of the nodes.
kpeter@696:     typedef typename _Traits::DistMap DistMap;
kpeter@696:     /// \brief The operation traits.
kpeter@696:     typedef typename _Traits::OperationTraits OperationTraits;
kpeter@696:   private:
kpeter@696:     /// Pointer to the underlying digraph.
kpeter@696:     const Digraph *digraph;
kpeter@696:     /// Pointer to the length map
kpeter@696:     const LengthMap *length;
kpeter@696:     ///Pointer to the map of predecessors arcs.
kpeter@696:     PredMap *_pred;
kpeter@696:     ///Indicates if \ref _pred is locally allocated (\c true) or not.
kpeter@696:     bool local_pred;
kpeter@696:     ///Pointer to the map of distances.
kpeter@696:     DistMap *_dist;
kpeter@696:     ///Indicates if \ref _dist is locally allocated (\c true) or not.
kpeter@696:     bool local_dist;
kpeter@696: 
kpeter@696:     typedef typename Digraph::template NodeMap<bool> MaskMap;
kpeter@696:     MaskMap *_mask;
kpeter@696: 
kpeter@696:     std::vector<Node> _process;
kpeter@696: 
kpeter@696:     /// Creates the maps if necessary.
kpeter@696:     void create_maps() {
kpeter@696:       if(!_pred) {
kpeter@696: 	local_pred = true;
kpeter@696: 	_pred = Traits::createPredMap(*digraph);
kpeter@696:       }
kpeter@696:       if(!_dist) {
kpeter@696: 	local_dist = true;
kpeter@696: 	_dist = Traits::createDistMap(*digraph);
kpeter@696:       }
kpeter@696:       _mask = new MaskMap(*digraph, false);
kpeter@696:     }
kpeter@696:     
kpeter@696:   public :
kpeter@696:  
kpeter@696:     typedef BellmanFord Create;
kpeter@696: 
kpeter@696:     /// \name Named template parameters
kpeter@696: 
kpeter@696:     ///@{
kpeter@696: 
kpeter@696:     template <class T>
kpeter@696:     struct DefPredMapTraits : public Traits {
kpeter@696:       typedef T PredMap;
kpeter@696:       static PredMap *createPredMap(const Digraph&) {
kpeter@696:         LEMON_ASSERT(false, "PredMap is not initialized");
kpeter@696:         return 0; // ignore warnings
kpeter@696:       }
kpeter@696:     };
kpeter@696: 
kpeter@696:     /// \brief \ref named-templ-param "Named parameter" for setting PredMap 
kpeter@696:     /// type
kpeter@696:     /// \ref named-templ-param "Named parameter" for setting PredMap type
kpeter@696:     ///
kpeter@696:     template <class T>
kpeter@696:     struct SetPredMap 
kpeter@696:       : public BellmanFord< Digraph, LengthMap, DefPredMapTraits<T> > {
kpeter@696:       typedef BellmanFord< Digraph, LengthMap, DefPredMapTraits<T> > Create;
kpeter@696:     };
kpeter@696:     
kpeter@696:     template <class T>
kpeter@696:     struct DefDistMapTraits : public Traits {
kpeter@696:       typedef T DistMap;
kpeter@696:       static DistMap *createDistMap(const Digraph&) {
kpeter@696:         LEMON_ASSERT(false, "DistMap is not initialized");
kpeter@696:         return 0; // ignore warnings
kpeter@696:       }
kpeter@696:     };
kpeter@696: 
kpeter@696:     /// \brief \ref named-templ-param "Named parameter" for setting DistMap 
kpeter@696:     /// type
kpeter@696:     ///
kpeter@696:     /// \ref named-templ-param "Named parameter" for setting DistMap type
kpeter@696:     ///
kpeter@696:     template <class T>
kpeter@696:     struct SetDistMap 
kpeter@696:       : public BellmanFord< Digraph, LengthMap, DefDistMapTraits<T> > {
kpeter@696:       typedef BellmanFord< Digraph, LengthMap, DefDistMapTraits<T> > Create;
kpeter@696:     };
kpeter@696:     
kpeter@696:     template <class T>
kpeter@696:     struct DefOperationTraitsTraits : public Traits {
kpeter@696:       typedef T OperationTraits;
kpeter@696:     };
kpeter@696:     
kpeter@696:     /// \brief \ref named-templ-param "Named parameter" for setting 
kpeter@696:     /// OperationTraits type
kpeter@696:     ///
kpeter@696:     /// \ref named-templ-param "Named parameter" for setting OperationTraits
kpeter@696:     /// type
kpeter@696:     template <class T>
kpeter@696:     struct SetOperationTraits
kpeter@696:       : public BellmanFord< Digraph, LengthMap, DefOperationTraitsTraits<T> > {
kpeter@696:       typedef BellmanFord< Digraph, LengthMap, DefOperationTraitsTraits<T> >
kpeter@696:       Create;
kpeter@696:     };
kpeter@696:     
kpeter@696:     ///@}
kpeter@696: 
kpeter@696:   protected:
kpeter@696:     
kpeter@696:     BellmanFord() {}
kpeter@696: 
kpeter@696:   public:      
kpeter@696:     
kpeter@696:     /// \brief Constructor.
kpeter@696:     ///
kpeter@696:     /// \param _graph the digraph the algorithm will run on.
kpeter@696:     /// \param _length the length map used by the algorithm.
kpeter@696:     BellmanFord(const Digraph& _graph, const LengthMap& _length) :
kpeter@696:       digraph(&_graph), length(&_length),
kpeter@696:       _pred(0), local_pred(false),
kpeter@696:       _dist(0), local_dist(false), _mask(0) {}
kpeter@696:     
kpeter@696:     ///Destructor.
kpeter@696:     ~BellmanFord() {
kpeter@696:       if(local_pred) delete _pred;
kpeter@696:       if(local_dist) delete _dist;
kpeter@696:       if(_mask) delete _mask;
kpeter@696:     }
kpeter@696: 
kpeter@696:     /// \brief Sets the length map.
kpeter@696:     ///
kpeter@696:     /// Sets the length map.
kpeter@696:     /// \return \c (*this)
kpeter@696:     BellmanFord &lengthMap(const LengthMap &m) {
kpeter@696:       length = &m;
kpeter@696:       return *this;
kpeter@696:     }
kpeter@696: 
kpeter@696:     /// \brief Sets the map storing the predecessor arcs.
kpeter@696:     ///
kpeter@696:     /// Sets the map storing the predecessor arcs.
kpeter@696:     /// If you don't use this function before calling \ref run(),
kpeter@696:     /// it will allocate one. The destuctor deallocates this
kpeter@696:     /// automatically allocated map, of course.
kpeter@696:     /// \return \c (*this)
kpeter@696:     BellmanFord &predMap(PredMap &m) {
kpeter@696:       if(local_pred) {
kpeter@696: 	delete _pred;
kpeter@696: 	local_pred=false;
kpeter@696:       }
kpeter@696:       _pred = &m;
kpeter@696:       return *this;
kpeter@696:     }
kpeter@696: 
kpeter@696:     /// \brief Sets the map storing the distances calculated by the algorithm.
kpeter@696:     ///
kpeter@696:     /// Sets the map storing the distances calculated by the algorithm.
kpeter@696:     /// If you don't use this function before calling \ref run(),
kpeter@696:     /// it will allocate one. The destuctor deallocates this
kpeter@696:     /// automatically allocated map, of course.
kpeter@696:     /// \return \c (*this)
kpeter@696:     BellmanFord &distMap(DistMap &m) {
kpeter@696:       if(local_dist) {
kpeter@696: 	delete _dist;
kpeter@696: 	local_dist=false;
kpeter@696:       }
kpeter@696:       _dist = &m;
kpeter@696:       return *this;
kpeter@696:     }
kpeter@696: 
kpeter@696:     /// \name Execution control
kpeter@696:     /// The simplest way to execute the algorithm is to use
kpeter@696:     /// one of the member functions called \c run(...).
kpeter@696:     /// \n
kpeter@696:     /// If you need more control on the execution,
kpeter@696:     /// first you must call \ref init(), then you can add several source nodes
kpeter@696:     /// with \ref addSource().
kpeter@696:     /// Finally \ref start() will perform the actual path
kpeter@696:     /// computation.
kpeter@696: 
kpeter@696:     ///@{
kpeter@696: 
kpeter@696:     /// \brief Initializes the internal data structures.
kpeter@696:     /// 
kpeter@696:     /// Initializes the internal data structures.
kpeter@696:     void init(const Value value = OperationTraits::infinity()) {
kpeter@696:       create_maps();
kpeter@696:       for (NodeIt it(*digraph); it != INVALID; ++it) {
kpeter@696: 	_pred->set(it, INVALID);
kpeter@696: 	_dist->set(it, value);
kpeter@696:       }
kpeter@696:       _process.clear();
kpeter@696:       if (OperationTraits::less(value, OperationTraits::infinity())) {
kpeter@696: 	for (NodeIt it(*digraph); it != INVALID; ++it) {
kpeter@696: 	  _process.push_back(it);
kpeter@696: 	  _mask->set(it, true);
kpeter@696: 	}
kpeter@696:       }
kpeter@696:     }
kpeter@696:     
kpeter@696:     /// \brief Adds a new source node.
kpeter@696:     ///
kpeter@696:     /// Adds a new source node. The optional second parameter is the 
kpeter@696:     /// initial distance of the node. It just sets the distance of the 
kpeter@696:     /// node to the given value.
kpeter@696:     void addSource(Node source, Value dst = OperationTraits::zero()) {
kpeter@696:       _dist->set(source, dst);
kpeter@696:       if (!(*_mask)[source]) {
kpeter@696: 	_process.push_back(source);
kpeter@696: 	_mask->set(source, true);
kpeter@696:       }
kpeter@696:     }
kpeter@696: 
kpeter@696:     /// \brief Executes one round from the Bellman-Ford algorithm.
kpeter@696:     ///
kpeter@696:     /// If the algoritm calculated the distances in the previous round
kpeter@696:     /// exactly for all at most \f$ k \f$ length path lengths then it will
kpeter@696:     /// calculate the distances exactly for all at most \f$ k + 1 \f$
kpeter@696:     /// length path lengths. With \f$ k \f$ iteration this function
kpeter@696:     /// calculates the at most \f$ k \f$ length path lengths.
kpeter@696:     ///
kpeter@696:     /// \warning The paths with limited arc number cannot be retrieved
kpeter@696:     /// easily with \ref path() or \ref predArc() functions. If you
kpeter@696:     /// need the shortest path and not just the distance you should store
kpeter@696:     /// after each iteration the \ref predMap() map and manually build
kpeter@696:     /// the path.
kpeter@696:     ///
kpeter@696:     /// \return \c true when the algorithm have not found more shorter
kpeter@696:     /// paths.
kpeter@696:     bool processNextRound() {
kpeter@696:       for (int i = 0; i < int(_process.size()); ++i) {
kpeter@696: 	_mask->set(_process[i], false);
kpeter@696:       }
kpeter@696:       std::vector<Node> nextProcess;
kpeter@696:       std::vector<Value> values(_process.size());
kpeter@696:       for (int i = 0; i < int(_process.size()); ++i) {
kpeter@696: 	values[i] = (*_dist)[_process[i]];
kpeter@696:       }
kpeter@696:       for (int i = 0; i < int(_process.size()); ++i) {
kpeter@696: 	for (OutArcIt it(*digraph, _process[i]); it != INVALID; ++it) {
kpeter@696: 	  Node target = digraph->target(it);
kpeter@696: 	  Value relaxed = OperationTraits::plus(values[i], (*length)[it]);
kpeter@696: 	  if (OperationTraits::less(relaxed, (*_dist)[target])) {
kpeter@696: 	    _pred->set(target, it);
kpeter@696: 	    _dist->set(target, relaxed);
kpeter@696: 	    if (!(*_mask)[target]) {
kpeter@696: 	      _mask->set(target, true);
kpeter@696: 	      nextProcess.push_back(target);
kpeter@696: 	    }
kpeter@696: 	  }	  
kpeter@696: 	}
kpeter@696:       }
kpeter@696:       _process.swap(nextProcess);
kpeter@696:       return _process.empty();
kpeter@696:     }
kpeter@696: 
kpeter@696:     /// \brief Executes one weak round from the Bellman-Ford algorithm.
kpeter@696:     ///
kpeter@696:     /// If the algorithm calculated the distances in the
kpeter@696:     /// previous round at least for all at most k length paths then it will
kpeter@696:     /// calculate the distances at least for all at most k + 1 length paths.
kpeter@696:     /// This function does not make it possible to calculate strictly the
kpeter@696:     /// at most k length minimal paths, this is why it is
kpeter@696:     /// called just weak round.
kpeter@696:     /// \return \c true when the algorithm have not found more shorter paths.
kpeter@696:     bool processNextWeakRound() {
kpeter@696:       for (int i = 0; i < int(_process.size()); ++i) {
kpeter@696: 	_mask->set(_process[i], false);
kpeter@696:       }
kpeter@696:       std::vector<Node> nextProcess;
kpeter@696:       for (int i = 0; i < int(_process.size()); ++i) {
kpeter@696: 	for (OutArcIt it(*digraph, _process[i]); it != INVALID; ++it) {
kpeter@696: 	  Node target = digraph->target(it);
kpeter@696: 	  Value relaxed = 
kpeter@696: 	    OperationTraits::plus((*_dist)[_process[i]], (*length)[it]);
kpeter@696: 	  if (OperationTraits::less(relaxed, (*_dist)[target])) {
kpeter@696: 	    _pred->set(target, it);
kpeter@696: 	    _dist->set(target, relaxed);
kpeter@696: 	    if (!(*_mask)[target]) {
kpeter@696: 	      _mask->set(target, true);
kpeter@696: 	      nextProcess.push_back(target);
kpeter@696: 	    }
kpeter@696: 	  }	  
kpeter@696: 	}
kpeter@696:       }
kpeter@696:       _process.swap(nextProcess);
kpeter@696:       return _process.empty();
kpeter@696:     }
kpeter@696: 
kpeter@696:     /// \brief Executes the algorithm.
kpeter@696:     ///
kpeter@696:     /// \pre init() must be called and at least one node should be added
kpeter@696:     /// with addSource() before using this function.
kpeter@696:     ///
kpeter@696:     /// This method runs the %BellmanFord algorithm from the root node(s)
kpeter@696:     /// in order to compute the shortest path to each node. The algorithm 
kpeter@696:     /// computes 
kpeter@696:     /// - The shortest path tree.
kpeter@696:     /// - The distance of each node from the root(s).
kpeter@696:     void start() {
kpeter@696:       int num = countNodes(*digraph) - 1;
kpeter@696:       for (int i = 0; i < num; ++i) {
kpeter@696: 	if (processNextWeakRound()) break;
kpeter@696:       }
kpeter@696:     }
kpeter@696: 
kpeter@696:     /// \brief Executes the algorithm and checks the negative cycles.
kpeter@696:     ///
kpeter@696:     /// \pre init() must be called and at least one node should be added
kpeter@696:     /// with addSource() before using this function. 
kpeter@696:     ///
kpeter@696:     /// This method runs the %BellmanFord algorithm from the root node(s)
kpeter@696:     /// in order to compute the shortest path to each node. The algorithm 
kpeter@696:     /// computes 
kpeter@696:     /// - The shortest path tree.
kpeter@696:     /// - The distance of each node from the root(s).
kpeter@696:     /// 
kpeter@696:     /// \return \c false if there is a negative cycle in the digraph.
kpeter@696:     bool checkedStart() {
kpeter@696:       int num = countNodes(*digraph);
kpeter@696:       for (int i = 0; i < num; ++i) {
kpeter@696: 	if (processNextWeakRound()) return true;
kpeter@696:       }
kpeter@696:       return _process.empty();
kpeter@696:     }
kpeter@696: 
kpeter@696:     /// \brief Executes the algorithm with path length limit.
kpeter@696:     ///
kpeter@696:     /// \pre init() must be called and at least one node should be added
kpeter@696:     /// with addSource() before using this function.
kpeter@696:     ///
kpeter@696:     /// This method runs the %BellmanFord algorithm from the root
kpeter@696:     /// node(s) in order to compute the shortest path lengths with at
kpeter@696:     /// most \c num arc.
kpeter@696:     ///
kpeter@696:     /// \warning The paths with limited arc number cannot be retrieved
kpeter@696:     /// easily with \ref path() or \ref predArc() functions. If you
kpeter@696:     /// need the shortest path and not just the distance you should store
kpeter@696:     /// after each iteration the \ref predMap() map and manually build
kpeter@696:     /// the path.
kpeter@696:     ///
kpeter@696:     /// The algorithm computes
kpeter@696:     /// - The predecessor arc from each node.
kpeter@696:     /// - The limited distance of each node from the root(s).
kpeter@696:     void limitedStart(int num) {
kpeter@696:       for (int i = 0; i < num; ++i) {
kpeter@696: 	if (processNextRound()) break;
kpeter@696:       }
kpeter@696:     }
kpeter@696:     
kpeter@696:     /// \brief Runs %BellmanFord algorithm from node \c s.
kpeter@696:     ///    
kpeter@696:     /// This method runs the %BellmanFord algorithm from a root node \c s
kpeter@696:     /// in order to compute the shortest path to each node. The algorithm 
kpeter@696:     /// computes
kpeter@696:     /// - The shortest path tree.
kpeter@696:     /// - The distance of each node from the root.
kpeter@696:     ///
kpeter@696:     /// \note d.run(s) is just a shortcut of the following code.
kpeter@696:     ///\code
kpeter@696:     ///  d.init();
kpeter@696:     ///  d.addSource(s);
kpeter@696:     ///  d.start();
kpeter@696:     ///\endcode
kpeter@696:     void run(Node s) {
kpeter@696:       init();
kpeter@696:       addSource(s);
kpeter@696:       start();
kpeter@696:     }
kpeter@696:     
kpeter@696:     /// \brief Runs %BellmanFord algorithm with limited path length 
kpeter@696:     /// from node \c s.
kpeter@696:     ///    
kpeter@696:     /// This method runs the %BellmanFord algorithm from a root node \c s
kpeter@696:     /// in order to compute the shortest path with at most \c len arcs 
kpeter@696:     /// to each node. The algorithm computes
kpeter@696:     /// - The shortest path tree.
kpeter@696:     /// - The distance of each node from the root.
kpeter@696:     ///
kpeter@696:     /// \note d.run(s, num) is just a shortcut of the following code.
kpeter@696:     ///\code
kpeter@696:     ///  d.init();
kpeter@696:     ///  d.addSource(s);
kpeter@696:     ///  d.limitedStart(num);
kpeter@696:     ///\endcode
kpeter@696:     void run(Node s, int num) {
kpeter@696:       init();
kpeter@696:       addSource(s);
kpeter@696:       limitedStart(num);
kpeter@696:     }
kpeter@696:     
kpeter@696:     ///@}
kpeter@696: 
kpeter@696:     /// \name Query Functions
kpeter@696:     /// The result of the %BellmanFord algorithm can be obtained using these
kpeter@696:     /// functions.\n
kpeter@696:     /// Before the use of these functions,
kpeter@696:     /// either run() or start() must be called.
kpeter@696:     
kpeter@696:     ///@{
kpeter@696: 
kpeter@696:     /// \brief Lemon iterator for get the active nodes.
kpeter@696:     ///
kpeter@696:     /// Lemon iterator for get the active nodes. This class provides a
kpeter@696:     /// common style lemon iterator which gives back a subset of the
kpeter@696:     /// nodes. The iterated nodes are active in the algorithm after
kpeter@696:     /// the last phase so these should be checked in the next phase to
kpeter@696:     /// find augmenting arcs from these.
kpeter@696:     class ActiveIt {
kpeter@696:     public:
kpeter@696: 
kpeter@696:       /// \brief Constructor.
kpeter@696:       ///
kpeter@696:       /// Constructor for get the nodeset of the variable. 
kpeter@696:       ActiveIt(const BellmanFord& algorithm) : _algorithm(&algorithm)
kpeter@696:       {
kpeter@696:         _index = _algorithm->_process.size() - 1;
kpeter@696:       }
kpeter@696: 
kpeter@696:       /// \brief Invalid constructor.
kpeter@696:       ///
kpeter@696:       /// Invalid constructor.
kpeter@696:       ActiveIt(Invalid) : _algorithm(0), _index(-1) {}
kpeter@696: 
kpeter@696:       /// \brief Conversion to node.
kpeter@696:       ///
kpeter@696:       /// Conversion to node.
kpeter@696:       operator Node() const { 
kpeter@696:         return _index >= 0 ? _algorithm->_process[_index] : INVALID;
kpeter@696:       }
kpeter@696: 
kpeter@696:       /// \brief Increment operator.
kpeter@696:       ///
kpeter@696:       /// Increment operator.
kpeter@696:       ActiveIt& operator++() {
kpeter@696:         --_index;
kpeter@696:         return *this; 
kpeter@696:       }
kpeter@696: 
kpeter@696:       bool operator==(const ActiveIt& it) const { 
kpeter@696:         return static_cast<Node>(*this) == static_cast<Node>(it); 
kpeter@696:       }
kpeter@696:       bool operator!=(const ActiveIt& it) const { 
kpeter@696:         return static_cast<Node>(*this) != static_cast<Node>(it); 
kpeter@696:       }
kpeter@696:       bool operator<(const ActiveIt& it) const { 
kpeter@696:         return static_cast<Node>(*this) < static_cast<Node>(it); 
kpeter@696:       }
kpeter@696:       
kpeter@696:     private:
kpeter@696:       const BellmanFord* _algorithm;
kpeter@696:       int _index;
kpeter@696:     };
kpeter@696: 
kpeter@696:     typedef PredMapPath<Digraph, PredMap> Path;
kpeter@696: 
kpeter@696:     /// \brief Gives back the shortest path.
kpeter@696:     ///    
kpeter@696:     /// Gives back the shortest path.
kpeter@696:     /// \pre The \c t should be reachable from the source.
kpeter@696:     Path path(Node t) 
kpeter@696:     {
kpeter@696:       return Path(*digraph, *_pred, t);
kpeter@696:     }
kpeter@696: 
kpeter@696: 
kpeter@696:     // TODO : implement negative cycle
kpeter@696: //     /// \brief Gives back a negative cycle.
kpeter@696: //     ///    
kpeter@696: //     /// This function gives back a negative cycle.
kpeter@696: //     /// If the algorithm have not found yet negative cycle it will give back
kpeter@696: //     /// an empty path.
kpeter@696: //     Path negativeCycle() {
kpeter@696: //       typename Digraph::template NodeMap<int> state(*digraph, 0);
kpeter@696: //       for (ActiveIt it(*this); it != INVALID; ++it) {
kpeter@696: //         if (state[it] == 0) {
kpeter@696: //           for (Node t = it; predArc(t) != INVALID; t = predNode(t)) {
kpeter@696: //             if (state[t] == 0) {
kpeter@696: //               state[t] = 1;
kpeter@696: //             } else if (state[t] == 2) {
kpeter@696: //               break;
kpeter@696: //             } else {
kpeter@696: //               p.clear();
kpeter@696: //               typename Path::Builder b(p);
kpeter@696: //               b.setStartNode(t);
kpeter@696: //               b.pushFront(predArc(t));
kpeter@696: //               for(Node s = predNode(t); s != t; s = predNode(s)) {
kpeter@696: //                 b.pushFront(predArc(s));
kpeter@696: //               }
kpeter@696: //               b.commit();
kpeter@696: //               return true;
kpeter@696: //             }
kpeter@696: //           }
kpeter@696: //           for (Node t = it; predArc(t) != INVALID; t = predNode(t)) {
kpeter@696: //             if (state[t] == 1) {
kpeter@696: //               state[t] = 2;
kpeter@696: //             } else {
kpeter@696: //               break;
kpeter@696: //             }
kpeter@696: //           }
kpeter@696: //         }
kpeter@696: //       }
kpeter@696: //       return false;
kpeter@696: //     }
kpeter@696: 	  
kpeter@696:     /// \brief The distance of a node from the root.
kpeter@696:     ///
kpeter@696:     /// Returns the distance of a node from the root.
kpeter@696:     /// \pre \ref run() must be called before using this function.
kpeter@696:     /// \warning If node \c v in unreachable from the root the return value
kpeter@696:     /// of this funcion is undefined.
kpeter@696:     Value dist(Node v) const { return (*_dist)[v]; }
kpeter@696: 
kpeter@696:     /// \brief Returns the 'previous arc' of the shortest path tree.
kpeter@696:     ///
kpeter@696:     /// For a node \c v it returns the 'previous arc' of the shortest path 
kpeter@696:     /// tree, i.e. it returns the last arc of a shortest path from the root 
kpeter@696:     /// to \c v. It is \ref INVALID if \c v is unreachable from the root or 
kpeter@696:     /// if \c v=s. The shortest path tree used here is equal to the shortest 
kpeter@696:     /// path tree used in \ref predNode(). 
kpeter@696:     /// \pre \ref run() must be called before using
kpeter@696:     /// this function.
kpeter@696:     Arc predArc(Node v) const { return (*_pred)[v]; }
kpeter@696: 
kpeter@696:     /// \brief Returns the 'previous node' of the shortest path tree.
kpeter@696:     ///
kpeter@696:     /// For a node \c v it returns the 'previous node' of the shortest path 
kpeter@696:     /// tree, i.e. it returns the last but one node from a shortest path from 
kpeter@696:     /// the root to \c /v. It is INVALID if \c v is unreachable from the root 
kpeter@696:     /// or if \c v=s. The shortest path tree used here is equal to the 
kpeter@696:     /// shortest path tree used in \ref predArc().  \pre \ref run() must be 
kpeter@696:     /// called before using this function.
kpeter@696:     Node predNode(Node v) const { 
kpeter@696:       return (*_pred)[v] == INVALID ? INVALID : digraph->source((*_pred)[v]); 
kpeter@696:     }
kpeter@696:     
kpeter@696:     /// \brief Returns a reference to the NodeMap of distances.
kpeter@696:     ///
kpeter@696:     /// Returns a reference to the NodeMap of distances. \pre \ref run() must
kpeter@696:     /// be called before using this function.
kpeter@696:     const DistMap &distMap() const { return *_dist;}
kpeter@696:  
kpeter@696:     /// \brief Returns a reference to the shortest path tree map.
kpeter@696:     ///
kpeter@696:     /// Returns a reference to the NodeMap of the arcs of the
kpeter@696:     /// shortest path tree.
kpeter@696:     /// \pre \ref run() must be called before using this function.
kpeter@696:     const PredMap &predMap() const { return *_pred; }
kpeter@696:  
kpeter@696:     /// \brief Checks if a node is reachable from the root.
kpeter@696:     ///
kpeter@696:     /// Returns \c true if \c v is reachable from the root.
kpeter@696:     /// \pre \ref run() must be called before using this function.
kpeter@696:     ///
kpeter@696:     bool reached(Node v) { return (*_dist)[v] != OperationTraits::infinity(); }
kpeter@696:     
kpeter@696:     ///@}
kpeter@696:   };
kpeter@696:  
kpeter@696:   /// \brief Default traits class of BellmanFord function.
kpeter@696:   ///
kpeter@696:   /// Default traits class of BellmanFord function.
kpeter@696:   /// \param _Digraph Digraph type.
kpeter@696:   /// \param _LengthMap Type of length map.
kpeter@696:   template <typename _Digraph, typename _LengthMap>
kpeter@696:   struct BellmanFordWizardDefaultTraits {
kpeter@696:     /// \brief The digraph type the algorithm runs on. 
kpeter@696:     typedef _Digraph Digraph;
kpeter@696: 
kpeter@696:     /// \brief The type of the map that stores the arc lengths.
kpeter@696:     ///
kpeter@696:     /// The type of the map that stores the arc lengths.
kpeter@696:     /// It must meet the \ref concepts::ReadMap "ReadMap" concept.
kpeter@696:     typedef _LengthMap LengthMap;
kpeter@696: 
kpeter@696:     /// \brief The value type of the length map.
kpeter@696:     typedef typename _LengthMap::Value Value;
kpeter@696: 
kpeter@696:     /// \brief Operation traits for Bellman-Ford algorithm.
kpeter@696:     ///
kpeter@696:     /// It defines the infinity type on the given Value type
kpeter@696:     /// and the used operation.
kpeter@696:     /// \see BellmanFordDefaultOperationTraits
kpeter@696:     typedef BellmanFordDefaultOperationTraits<Value> OperationTraits;
kpeter@696: 
kpeter@696:     /// \brief The type of the map that stores the last
kpeter@696:     /// arcs of the shortest paths.
kpeter@696:     /// 
kpeter@696:     /// The type of the map that stores the last
kpeter@696:     /// arcs of the shortest paths.
kpeter@696:     /// It must meet the \ref concepts::WriteMap "WriteMap" concept.
kpeter@696:     typedef NullMap <typename _Digraph::Node,typename _Digraph::Arc> PredMap;
kpeter@696: 
kpeter@696:     /// \brief Instantiates a PredMap.
kpeter@696:     /// 
kpeter@696:     /// This function instantiates a \ref PredMap. 
kpeter@696:     static PredMap *createPredMap(const _Digraph &) {
kpeter@696:       return new PredMap();
kpeter@696:     }
kpeter@696:     /// \brief The type of the map that stores the dists of the nodes.
kpeter@696:     ///
kpeter@696:     /// The type of the map that stores the dists of the nodes.
kpeter@696:     /// It must meet the \ref concepts::WriteMap "WriteMap" concept.
kpeter@696:     typedef NullMap<typename Digraph::Node, Value> DistMap;
kpeter@696:     /// \brief Instantiates a DistMap.
kpeter@696:     ///
kpeter@696:     /// This function instantiates a \ref DistMap. 
kpeter@696:     static DistMap *createDistMap(const _Digraph &) {
kpeter@696:       return new DistMap();
kpeter@696:     }
kpeter@696:   };
kpeter@696:   
kpeter@696:   /// \brief Default traits used by \ref BellmanFordWizard
kpeter@696:   ///
kpeter@696:   /// To make it easier to use BellmanFord algorithm
kpeter@696:   /// we have created a wizard class.
kpeter@696:   /// This \ref BellmanFordWizard class needs default traits,
kpeter@696:   /// as well as the \ref BellmanFord class.
kpeter@696:   /// The \ref BellmanFordWizardBase is a class to be the default traits of the
kpeter@696:   /// \ref BellmanFordWizard class.
kpeter@696:   /// \todo More named parameters are required...
kpeter@696:   template<class _Digraph,class _LengthMap>
kpeter@696:   class BellmanFordWizardBase 
kpeter@696:     : public BellmanFordWizardDefaultTraits<_Digraph,_LengthMap> {
kpeter@696: 
kpeter@696:     typedef BellmanFordWizardDefaultTraits<_Digraph,_LengthMap> Base;
kpeter@696:   protected:
kpeter@696:     /// Type of the nodes in the digraph.
kpeter@696:     typedef typename Base::Digraph::Node Node;
kpeter@696: 
kpeter@696:     /// Pointer to the underlying digraph.
kpeter@696:     void *_graph;
kpeter@696:     /// Pointer to the length map
kpeter@696:     void *_length;
kpeter@696:     ///Pointer to the map of predecessors arcs.
kpeter@696:     void *_pred;
kpeter@696:     ///Pointer to the map of distances.
kpeter@696:     void *_dist;
kpeter@696:     ///Pointer to the source node.
kpeter@696:     Node _source;
kpeter@696: 
kpeter@696:     public:
kpeter@696:     /// Constructor.
kpeter@696:     
kpeter@696:     /// This constructor does not require parameters, therefore it initiates
kpeter@696:     /// all of the attributes to default values (0, INVALID).
kpeter@696:     BellmanFordWizardBase() : _graph(0), _length(0), _pred(0),
kpeter@696: 			   _dist(0), _source(INVALID) {}
kpeter@696: 
kpeter@696:     /// Constructor.
kpeter@696:     
kpeter@696:     /// This constructor requires some parameters,
kpeter@696:     /// listed in the parameters list.
kpeter@696:     /// Others are initiated to 0.
kpeter@696:     /// \param digraph is the initial value of  \ref _graph
kpeter@696:     /// \param length is the initial value of  \ref _length
kpeter@696:     /// \param source is the initial value of  \ref _source
kpeter@696:     BellmanFordWizardBase(const _Digraph& digraph, 
kpeter@696: 			  const _LengthMap& length, 
kpeter@696: 			  Node source = INVALID) :
kpeter@696:       _graph(reinterpret_cast<void*>(const_cast<_Digraph*>(&digraph))), 
kpeter@696:       _length(reinterpret_cast<void*>(const_cast<_LengthMap*>(&length))), 
kpeter@696:       _pred(0), _dist(0), _source(source) {}
kpeter@696: 
kpeter@696:   };
kpeter@696:   
kpeter@696:   /// A class to make the usage of BellmanFord algorithm easier
kpeter@696: 
kpeter@696:   /// This class is created to make it easier to use BellmanFord algorithm.
kpeter@696:   /// It uses the functions and features of the plain \ref BellmanFord,
kpeter@696:   /// but it is much simpler to use it.
kpeter@696:   ///
kpeter@696:   /// Simplicity means that the way to change the types defined
kpeter@696:   /// in the traits class is based on functions that returns the new class
kpeter@696:   /// and not on templatable built-in classes.
kpeter@696:   /// When using the plain \ref BellmanFord
kpeter@696:   /// the new class with the modified type comes from
kpeter@696:   /// the original class by using the ::
kpeter@696:   /// operator. In the case of \ref BellmanFordWizard only
kpeter@696:   /// a function have to be called and it will
kpeter@696:   /// return the needed class.
kpeter@696:   ///
kpeter@696:   /// It does not have own \ref run method. When its \ref run method is called
kpeter@696:   /// it initiates a plain \ref BellmanFord class, and calls the \ref 
kpeter@696:   /// BellmanFord::run method of it.
kpeter@696:   template<class _Traits>
kpeter@696:   class BellmanFordWizard : public _Traits {
kpeter@696:     typedef _Traits Base;
kpeter@696: 
kpeter@696:     ///The type of the underlying digraph.
kpeter@696:     typedef typename _Traits::Digraph Digraph;
kpeter@696: 
kpeter@696:     typedef typename Digraph::Node Node;
kpeter@696:     typedef typename Digraph::NodeIt NodeIt;
kpeter@696:     typedef typename Digraph::Arc Arc;
kpeter@696:     typedef typename Digraph::OutArcIt ArcIt;
kpeter@696:     
kpeter@696:     ///The type of the map that stores the arc lengths.
kpeter@696:     typedef typename _Traits::LengthMap LengthMap;
kpeter@696: 
kpeter@696:     ///The type of the length of the arcs.
kpeter@696:     typedef typename LengthMap::Value Value;
kpeter@696: 
kpeter@696:     ///\brief The type of the map that stores the last
kpeter@696:     ///arcs of the shortest paths.
kpeter@696:     typedef typename _Traits::PredMap PredMap;
kpeter@696: 
kpeter@696:     ///The type of the map that stores the dists of the nodes.
kpeter@696:     typedef typename _Traits::DistMap DistMap;
kpeter@696: 
kpeter@696:   public:
kpeter@696:     /// Constructor.
kpeter@696:     BellmanFordWizard() : _Traits() {}
kpeter@696: 
kpeter@696:     /// \brief Constructor that requires parameters.
kpeter@696:     ///
kpeter@696:     /// Constructor that requires parameters.
kpeter@696:     /// These parameters will be the default values for the traits class.
kpeter@696:     BellmanFordWizard(const Digraph& digraph, const LengthMap& length, 
kpeter@696: 		      Node src = INVALID) 
kpeter@696:       : _Traits(digraph, length, src) {}
kpeter@696: 
kpeter@696:     /// \brief Copy constructor
kpeter@696:     BellmanFordWizard(const _Traits &b) : _Traits(b) {}
kpeter@696: 
kpeter@696:     ~BellmanFordWizard() {}
kpeter@696: 
kpeter@696:     /// \brief Runs BellmanFord algorithm from a given node.
kpeter@696:     ///    
kpeter@696:     /// Runs BellmanFord algorithm from a given node.
kpeter@696:     /// The node can be given by the \ref source function.
kpeter@696:     void run() {
kpeter@696:       LEMON_ASSERT(Base::_source != INVALID, "Source node is not given");
kpeter@696:       BellmanFord<Digraph,LengthMap,_Traits> 
kpeter@696: 	bf(*reinterpret_cast<const Digraph*>(Base::_graph), 
kpeter@696:            *reinterpret_cast<const LengthMap*>(Base::_length));
kpeter@696:       if (Base::_pred) bf.predMap(*reinterpret_cast<PredMap*>(Base::_pred));
kpeter@696:       if (Base::_dist) bf.distMap(*reinterpret_cast<DistMap*>(Base::_dist));
kpeter@696:       bf.run(Base::_source);
kpeter@696:     }
kpeter@696: 
kpeter@696:     /// \brief Runs BellmanFord algorithm from the given node.
kpeter@696:     ///
kpeter@696:     /// Runs BellmanFord algorithm from the given node.
kpeter@696:     /// \param src is the given source.
kpeter@696:     void run(Node src) {
kpeter@696:       Base::_source = src;
kpeter@696:       run();
kpeter@696:     }
kpeter@696: 
kpeter@696:     template<class T>
kpeter@696:     struct DefPredMapBase : public Base {
kpeter@696:       typedef T PredMap;
kpeter@696:       static PredMap *createPredMap(const Digraph &) { return 0; };
kpeter@696:       DefPredMapBase(const _Traits &b) : _Traits(b) {}
kpeter@696:     };
kpeter@696:     
kpeter@696:     ///\brief \ref named-templ-param "Named parameter"
kpeter@696:     ///function for setting PredMap type
kpeter@696:     ///
kpeter@696:     /// \ref named-templ-param "Named parameter"
kpeter@696:     ///function for setting PredMap type
kpeter@696:     ///
kpeter@696:     template<class T>
kpeter@696:     BellmanFordWizard<DefPredMapBase<T> > predMap(const T &t) 
kpeter@696:     {
kpeter@696:       Base::_pred=reinterpret_cast<void*>(const_cast<T*>(&t));
kpeter@696:       return BellmanFordWizard<DefPredMapBase<T> >(*this);
kpeter@696:     }
kpeter@696:     
kpeter@696:     template<class T>
kpeter@696:     struct DefDistMapBase : public Base {
kpeter@696:       typedef T DistMap;
kpeter@696:       static DistMap *createDistMap(const Digraph &) { return 0; };
kpeter@696:       DefDistMapBase(const _Traits &b) : _Traits(b) {}
kpeter@696:     };
kpeter@696:     
kpeter@696:     ///\brief \ref named-templ-param "Named parameter"
kpeter@696:     ///function for setting DistMap type
kpeter@696:     ///
kpeter@696:     /// \ref named-templ-param "Named parameter"
kpeter@696:     ///function for setting DistMap type
kpeter@696:     ///
kpeter@696:     template<class T>
kpeter@696:     BellmanFordWizard<DefDistMapBase<T> > distMap(const T &t) {
kpeter@696:       Base::_dist=reinterpret_cast<void*>(const_cast<T*>(&t));
kpeter@696:       return BellmanFordWizard<DefDistMapBase<T> >(*this);
kpeter@696:     }
kpeter@696: 
kpeter@696:     template<class T>
kpeter@696:     struct DefOperationTraitsBase : public Base {
kpeter@696:       typedef T OperationTraits;
kpeter@696:       DefOperationTraitsBase(const _Traits &b) : _Traits(b) {}
kpeter@696:     };
kpeter@696:     
kpeter@696:     ///\brief \ref named-templ-param "Named parameter"
kpeter@696:     ///function for setting OperationTraits type
kpeter@696:     ///
kpeter@696:     /// \ref named-templ-param "Named parameter"
kpeter@696:     ///function for setting OperationTraits type
kpeter@696:     ///
kpeter@696:     template<class T>
kpeter@696:     BellmanFordWizard<DefOperationTraitsBase<T> > distMap() {
kpeter@696:       return BellmanFordWizard<DefDistMapBase<T> >(*this);
kpeter@696:     }
kpeter@696:     
kpeter@696:     /// \brief Sets the source node, from which the BellmanFord algorithm runs.
kpeter@696:     ///
kpeter@696:     /// Sets the source node, from which the BellmanFord algorithm runs.
kpeter@696:     /// \param src is the source node.
kpeter@696:     BellmanFordWizard<_Traits>& source(Node src) {
kpeter@696:       Base::_source = src;
kpeter@696:       return *this;
kpeter@696:     }
kpeter@696:     
kpeter@696:   };
kpeter@696:   
kpeter@696:   /// \brief Function type interface for BellmanFord algorithm.
kpeter@696:   ///
kpeter@696:   /// \ingroup shortest_path
kpeter@696:   /// Function type interface for BellmanFord algorithm.
kpeter@696:   ///
kpeter@696:   /// This function also has several \ref named-templ-func-param 
kpeter@696:   /// "named parameters", they are declared as the members of class 
kpeter@696:   /// \ref BellmanFordWizard.
kpeter@696:   /// The following
kpeter@696:   /// example shows how to use these parameters.
kpeter@696:   ///\code
kpeter@696:   /// bellmanford(g,length,source).predMap(preds).run();
kpeter@696:   ///\endcode
kpeter@696:   /// \warning Don't forget to put the \ref BellmanFordWizard::run() "run()"
kpeter@696:   /// to the end of the parameter list.
kpeter@696:   /// \sa BellmanFordWizard
kpeter@696:   /// \sa BellmanFord
kpeter@696:   template<class _Digraph, class _LengthMap>
kpeter@696:   BellmanFordWizard<BellmanFordWizardBase<_Digraph,_LengthMap> >
kpeter@696:   bellmanFord(const _Digraph& digraph,
kpeter@696: 	      const _LengthMap& length, 
kpeter@696: 	      typename _Digraph::Node source = INVALID) {
kpeter@696:     return BellmanFordWizard<BellmanFordWizardBase<_Digraph,_LengthMap> >
kpeter@696:       (digraph, length, source);
kpeter@696:   }
kpeter@696: 
kpeter@696: } //END OF NAMESPACE LEMON
kpeter@696: 
kpeter@696: #endif
kpeter@696: