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@697: #ifndef LEMON_BELLMAN_FORD_H
kpeter@697: #define LEMON_BELLMAN_FORD_H
kpeter@696: 
kpeter@696: /// \ingroup shortest_path
kpeter@696: /// \file
kpeter@696: /// \brief Bellman-Ford algorithm.
kpeter@696: 
kpeter@781: #include <lemon/list_graph.h>
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@697: #include <lemon/path.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@697:   /// This operation traits class defines all computational operations
kpeter@697:   /// and constants that are used in the Bellman-Ford algorithm.
kpeter@697:   /// The default implementation is based on the \c numeric_limits class.
kpeter@697:   /// If the numeric type does not have infinity value, then the maximum
kpeter@697:   /// value is used as extremal infinity value.
kpeter@696:   template <
kpeter@697:     typename V, 
kpeter@697:     bool has_inf = std::numeric_limits<V>::has_infinity>
kpeter@696:   struct BellmanFordDefaultOperationTraits {
kpeter@697:     /// \e
kpeter@697:     typedef V Value;
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@697:     /// \brief Gives back \c true only if the first value is less than
kpeter@697:     /// 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@697:   template <typename V>
kpeter@697:   struct BellmanFordDefaultOperationTraits<V, false> {
kpeter@697:     typedef V Value;
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@697:   /// \param GR The type of the digraph.
kpeter@697:   /// \param LEN The type of the length map.
kpeter@697:   template<typename GR, typename LEN>
kpeter@696:   struct BellmanFordDefaultTraits {
kpeter@697:     /// The type of the digraph the algorithm runs on. 
kpeter@697:     typedef GR 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@697:     /// It must conform to the \ref concepts::ReadMap "ReadMap" concept.
kpeter@697:     typedef LEN LengthMap;
kpeter@696: 
kpeter@697:     /// The type of the arc lengths.
kpeter@697:     typedef typename LEN::Value Value;
kpeter@696: 
kpeter@696:     /// \brief Operation traits for Bellman-Ford algorithm.
kpeter@696:     ///
kpeter@697:     /// It defines the used operations and the infinity value for the
kpeter@697:     /// given \c Value type.
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@697:     /// It must conform to the \ref concepts::WriteMap "WriteMap" concept.
kpeter@697:     typedef typename GR::template NodeMap<typename GR::Arc> PredMap;
kpeter@696: 
kpeter@697:     /// \brief Instantiates a \c PredMap.
kpeter@696:     /// 
kpeter@696:     /// This function instantiates a \ref PredMap. 
kpeter@697:     /// \param g is the digraph to which we would like to define the
kpeter@697:     /// \ref PredMap.
kpeter@697:     static PredMap *createPredMap(const GR& g) {
kpeter@697:       return new PredMap(g);
kpeter@696:     }
kpeter@696: 
kpeter@697:     /// \brief The type of the map that stores the distances of the nodes.
kpeter@696:     ///
kpeter@697:     /// The type of the map that stores the distances of the nodes.
kpeter@697:     /// It must conform to the \ref concepts::WriteMap "WriteMap" concept.
kpeter@697:     typedef typename GR::template NodeMap<typename LEN::Value> DistMap;
kpeter@696: 
kpeter@697:     /// \brief Instantiates a \c DistMap.
kpeter@696:     ///
kpeter@696:     /// This function instantiates a \ref DistMap. 
kpeter@697:     /// \param g is the digraph to which we would like to define the 
kpeter@697:     /// \ref DistMap.
kpeter@697:     static DistMap *createDistMap(const GR& g) {
kpeter@697:       return new DistMap(g);
kpeter@696:     }
kpeter@696: 
kpeter@696:   };
kpeter@696:   
kpeter@696:   /// \brief %BellmanFord algorithm class.
kpeter@696:   ///
kpeter@696:   /// \ingroup shortest_path
kpeter@697:   /// This class provides an efficient implementation of the Bellman-Ford 
kpeter@697:   /// algorithm. The maximum time complexity of the algorithm is
kpeter@697:   /// <tt>O(ne)</tt>.
kpeter@697:   ///
kpeter@697:   /// The Bellman-Ford algorithm solves the single-source shortest path
kpeter@697:   /// problem when the arcs can have negative lengths, but the digraph
kpeter@697:   /// should not contain directed cycles with negative total length.
kpeter@697:   /// If all arc costs are non-negative, consider to use the Dijkstra
kpeter@697:   /// algorithm instead, since it is more efficient.
kpeter@697:   ///
kpeter@697:   /// 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@697:   /// kind of length. The type of the length values is determined by the
kpeter@697:   /// \ref concepts::ReadMap::Value "Value" type of the length map.
kpeter@696:   ///
kpeter@697:   /// There is also a \ref bellmanFord() "function-type interface" for the
kpeter@697:   /// Bellman-Ford algorithm, which is convenient in the simplier cases and
kpeter@697:   /// it can be used easier.
kpeter@696:   ///
kpeter@697:   /// \tparam GR The type of the digraph the algorithm runs on.
kpeter@697:   /// The default type is \ref ListDigraph.
kpeter@697:   /// \tparam LEN A \ref concepts::ReadMap "readable" arc map that specifies
kpeter@697:   /// the lengths of the arcs. The default map type is
kpeter@697:   /// \ref concepts::Digraph::ArcMap "GR::ArcMap<int>".
kpeter@825:   /// \tparam TR The traits class that defines various types used by the
kpeter@825:   /// algorithm. By default, it is \ref BellmanFordDefaultTraits
kpeter@825:   /// "BellmanFordDefaultTraits<GR, LEN>".
kpeter@825:   /// In most cases, this parameter should not be set directly,
kpeter@825:   /// consider to use the named template parameters instead.
kpeter@696: #ifdef DOXYGEN
kpeter@697:   template <typename GR, typename LEN, typename TR>
kpeter@696: #else
kpeter@697:   template <typename GR=ListDigraph,
kpeter@697:             typename LEN=typename GR::template ArcMap<int>,
kpeter@697:             typename TR=BellmanFordDefaultTraits<GR,LEN> >
kpeter@696: #endif
kpeter@696:   class BellmanFord {
kpeter@696:   public:
kpeter@696: 
kpeter@696:     ///The type of the underlying digraph.
kpeter@697:     typedef typename TR::Digraph Digraph;
kpeter@697:     
kpeter@697:     /// \brief The type of the arc lengths.
kpeter@697:     typedef typename TR::LengthMap::Value Value;
kpeter@697:     /// \brief The type of the map that stores the arc lengths.
kpeter@697:     typedef typename TR::LengthMap LengthMap;
kpeter@697:     /// \brief The type of the map that stores the last
kpeter@697:     /// arcs of the shortest paths.
kpeter@697:     typedef typename TR::PredMap PredMap;
kpeter@697:     /// \brief The type of the map that stores the distances of the nodes.
kpeter@697:     typedef typename TR::DistMap DistMap;
kpeter@697:     /// The type of the paths.
kpeter@697:     typedef PredMapPath<Digraph, PredMap> Path;
kpeter@697:     ///\brief The \ref BellmanFordDefaultOperationTraits
kpeter@697:     /// "operation traits class" of the algorithm.
kpeter@697:     typedef typename TR::OperationTraits OperationTraits;
kpeter@697: 
kpeter@697:     ///The \ref BellmanFordDefaultTraits "traits class" of the algorithm.
kpeter@697:     typedef TR Traits;
kpeter@697: 
kpeter@697:   private:
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@697: 
kpeter@697:     // Pointer to the underlying digraph.
kpeter@697:     const Digraph *_gr;
kpeter@697:     // Pointer to the length map
kpeter@697:     const LengthMap *_length;
kpeter@697:     // Pointer to the map of predecessors arcs.
kpeter@696:     PredMap *_pred;
kpeter@697:     // Indicates if _pred is locally allocated (true) or not.
kpeter@697:     bool _local_pred;
kpeter@697:     // Pointer to the map of distances.
kpeter@696:     DistMap *_dist;
kpeter@697:     // Indicates if _dist is locally allocated (true) or not.
kpeter@697:     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@697:     // Creates the maps if necessary.
kpeter@696:     void create_maps() {
kpeter@696:       if(!_pred) {
kpeter@697: 	_local_pred = true;
kpeter@697: 	_pred = Traits::createPredMap(*_gr);
kpeter@696:       }
kpeter@696:       if(!_dist) {
kpeter@697: 	_local_dist = true;
kpeter@697: 	_dist = Traits::createDistMap(*_gr);
kpeter@696:       }
kpeter@804:       if(!_mask) {
kpeter@804:         _mask = new MaskMap(*_gr);
kpeter@804:       }
kpeter@696:     }
kpeter@696:     
kpeter@696:   public :
kpeter@696:  
kpeter@696:     typedef BellmanFord Create;
kpeter@696: 
kpeter@697:     /// \name Named Template Parameters
kpeter@696: 
kpeter@696:     ///@{
kpeter@696: 
kpeter@696:     template <class T>
kpeter@697:     struct SetPredMapTraits : 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@697:     /// \brief \ref named-templ-param "Named parameter" for setting
kpeter@697:     /// \c PredMap type.
kpeter@696:     ///
kpeter@697:     /// \ref named-templ-param "Named parameter" for setting
kpeter@697:     /// \c PredMap type.
kpeter@697:     /// It must conform to the \ref concepts::WriteMap "WriteMap" concept.
kpeter@696:     template <class T>
kpeter@696:     struct SetPredMap 
kpeter@697:       : public BellmanFord< Digraph, LengthMap, SetPredMapTraits<T> > {
kpeter@697:       typedef BellmanFord< Digraph, LengthMap, SetPredMapTraits<T> > Create;
kpeter@696:     };
kpeter@696:     
kpeter@696:     template <class T>
kpeter@697:     struct SetDistMapTraits : 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@697:     /// \brief \ref named-templ-param "Named parameter" for setting
kpeter@697:     /// \c DistMap type.
kpeter@696:     ///
kpeter@697:     /// \ref named-templ-param "Named parameter" for setting
kpeter@697:     /// \c DistMap type.
kpeter@697:     /// It must conform to the \ref concepts::WriteMap "WriteMap" concept.
kpeter@696:     template <class T>
kpeter@696:     struct SetDistMap 
kpeter@697:       : public BellmanFord< Digraph, LengthMap, SetDistMapTraits<T> > {
kpeter@697:       typedef BellmanFord< Digraph, LengthMap, SetDistMapTraits<T> > Create;
kpeter@696:     };
kpeter@697: 
kpeter@696:     template <class T>
kpeter@697:     struct SetOperationTraitsTraits : public Traits {
kpeter@696:       typedef T OperationTraits;
kpeter@696:     };
kpeter@696:     
kpeter@696:     /// \brief \ref named-templ-param "Named parameter" for setting 
kpeter@697:     /// \c OperationTraits type.
kpeter@696:     ///
kpeter@697:     /// \ref named-templ-param "Named parameter" for setting
kpeter@697:     /// \c OperationTraits type.
kpeter@786:     /// For more information, see \ref BellmanFordDefaultOperationTraits.
kpeter@696:     template <class T>
kpeter@696:     struct SetOperationTraits
kpeter@697:       : public BellmanFord< Digraph, LengthMap, SetOperationTraitsTraits<T> > {
kpeter@697:       typedef BellmanFord< Digraph, LengthMap, SetOperationTraitsTraits<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@697:     /// Constructor.
kpeter@697:     /// \param g The digraph the algorithm runs on.
kpeter@697:     /// \param length The length map used by the algorithm.
kpeter@697:     BellmanFord(const Digraph& g, const LengthMap& length) :
kpeter@697:       _gr(&g), _length(&length),
kpeter@697:       _pred(0), _local_pred(false),
kpeter@697:       _dist(0), _local_dist(false), _mask(0) {}
kpeter@696:     
kpeter@696:     ///Destructor.
kpeter@696:     ~BellmanFord() {
kpeter@697:       if(_local_pred) delete _pred;
kpeter@697:       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@697:     /// \return <tt>(*this)</tt>
kpeter@697:     BellmanFord &lengthMap(const LengthMap &map) {
kpeter@697:       _length = &map;
kpeter@696:       return *this;
kpeter@696:     }
kpeter@696: 
kpeter@697:     /// \brief Sets the map that stores the predecessor arcs.
kpeter@696:     ///
kpeter@697:     /// Sets the map that stores the predecessor arcs.
kpeter@697:     /// If you don't use this function before calling \ref run()
kpeter@697:     /// or \ref init(), an instance will be allocated automatically.
kpeter@697:     /// The destructor deallocates this automatically allocated map,
kpeter@697:     /// of course.
kpeter@697:     /// \return <tt>(*this)</tt>
kpeter@697:     BellmanFord &predMap(PredMap &map) {
kpeter@697:       if(_local_pred) {
kpeter@696: 	delete _pred;
kpeter@697: 	_local_pred=false;
kpeter@696:       }
kpeter@697:       _pred = &map;
kpeter@696:       return *this;
kpeter@696:     }
kpeter@696: 
kpeter@697:     /// \brief Sets the map that stores the distances of the nodes.
kpeter@696:     ///
kpeter@697:     /// Sets the map that stores the distances of the nodes calculated
kpeter@697:     /// by the algorithm.
kpeter@697:     /// If you don't use this function before calling \ref run()
kpeter@697:     /// or \ref init(), an instance will be allocated automatically.
kpeter@697:     /// The destructor deallocates this automatically allocated map,
kpeter@697:     /// of course.
kpeter@697:     /// \return <tt>(*this)</tt>
kpeter@697:     BellmanFord &distMap(DistMap &map) {
kpeter@697:       if(_local_dist) {
kpeter@696: 	delete _dist;
kpeter@697: 	_local_dist=false;
kpeter@696:       }
kpeter@697:       _dist = &map;
kpeter@696:       return *this;
kpeter@696:     }
kpeter@696: 
kpeter@697:     /// \name Execution Control
kpeter@697:     /// The simplest way to execute the Bellman-Ford algorithm is to use
kpeter@697:     /// one of the member functions called \ref run().\n
kpeter@697:     /// If you need better control on the execution, you have to call
kpeter@697:     /// \ref init() first, then you can add several source nodes
kpeter@697:     /// with \ref addSource(). Finally the actual path computation can be
kpeter@697:     /// performed with \ref start(), \ref checkedStart() or
kpeter@697:     /// \ref limitedStart().
kpeter@696: 
kpeter@696:     ///@{
kpeter@696: 
kpeter@696:     /// \brief Initializes the internal data structures.
kpeter@696:     /// 
kpeter@697:     /// Initializes the internal data structures. The optional parameter
kpeter@697:     /// is the initial distance of each node.
kpeter@696:     void init(const Value value = OperationTraits::infinity()) {
kpeter@696:       create_maps();
kpeter@697:       for (NodeIt it(*_gr); 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@697: 	for (NodeIt it(*_gr); it != INVALID; ++it) {
kpeter@696: 	  _process.push_back(it);
kpeter@696: 	  _mask->set(it, true);
kpeter@696: 	}
kpeter@804:       } else {
kpeter@804: 	for (NodeIt it(*_gr); it != INVALID; ++it) {
kpeter@804: 	  _mask->set(it, false);
kpeter@804: 	}
kpeter@696:       }
kpeter@696:     }
kpeter@696:     
kpeter@696:     /// \brief Adds a new source node.
kpeter@696:     ///
kpeter@697:     /// This function adds a new source node. The optional second parameter
kpeter@697:     /// is the initial distance of the node.
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@697:     /// exactly for the paths of at most \c k arcs, then this function
kpeter@697:     /// will calculate the distances exactly for the paths of at most
kpeter@697:     /// <tt>k+1</tt> arcs. Performing \c k iterations using this function
kpeter@697:     /// calculates the shortest path distances exactly for the paths
kpeter@697:     /// consisting of at most \c k arcs.
kpeter@696:     ///
kpeter@696:     /// \warning The paths with limited arc number cannot be retrieved
kpeter@697:     /// easily with \ref path() or \ref predArc() functions. If you also
kpeter@697:     /// need the shortest paths and not only the distances, you should
kpeter@697:     /// store the \ref predMap() "predecessor map" after each iteration
kpeter@697:     /// and build the path manually.
kpeter@696:     ///
kpeter@696:     /// \return \c true when the algorithm have not found more shorter
kpeter@696:     /// paths.
kpeter@697:     ///
kpeter@697:     /// \see ActiveIt
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@697: 	for (OutArcIt it(*_gr, _process[i]); it != INVALID; ++it) {
kpeter@697: 	  Node target = _gr->target(it);
kpeter@697: 	  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@697:     /// If the algorithm calculated the distances in the previous round
kpeter@697:     /// at least for the paths of at most \c k arcs, then this function
kpeter@697:     /// will calculate the distances at least for the paths of at most
kpeter@697:     /// <tt>k+1</tt> arcs.
kpeter@697:     /// This function does not make it possible to calculate the shortest
kpeter@697:     /// path distances exactly for paths consisting of at most \c k arcs,
kpeter@697:     /// this is why it is called weak round.
kpeter@697:     ///
kpeter@697:     /// \return \c true when the algorithm have not found more shorter
kpeter@697:     /// paths.
kpeter@697:     ///
kpeter@697:     /// \see ActiveIt
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@697: 	for (OutArcIt it(*_gr, _process[i]); it != INVALID; ++it) {
kpeter@697: 	  Node target = _gr->target(it);
kpeter@696: 	  Value relaxed = 
kpeter@697: 	    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@697:     /// Executes the algorithm.
kpeter@696:     ///
kpeter@697:     /// This method runs the Bellman-Ford algorithm from the root node(s)
kpeter@697:     /// in order to compute the shortest path to each node.
kpeter@697:     ///
kpeter@697:     /// The algorithm computes
kpeter@697:     /// - the shortest path tree (forest),
kpeter@697:     /// - the distance of each node from the root(s).
kpeter@697:     ///
kpeter@697:     /// \pre init() must be called and at least one root node should be
kpeter@697:     /// added with addSource() before using this function.
kpeter@696:     void start() {
kpeter@697:       int num = countNodes(*_gr) - 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@697:     /// Executes the algorithm and checks the negative cycles.
kpeter@696:     ///
kpeter@697:     /// This method runs the Bellman-Ford algorithm from the root node(s)
kpeter@697:     /// in order to compute the shortest path to each node and also checks
kpeter@697:     /// if the digraph contains cycles with negative total length.
kpeter@697:     ///
kpeter@697:     /// The algorithm computes 
kpeter@697:     /// - the shortest path tree (forest),
kpeter@697:     /// - 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@697:     ///
kpeter@697:     /// \pre init() must be called and at least one root node should be
kpeter@697:     /// added with addSource() before using this function. 
kpeter@696:     bool checkedStart() {
kpeter@697:       int num = countNodes(*_gr);
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@697:     /// \brief Executes the algorithm with arc number limit.
kpeter@696:     ///
kpeter@697:     /// Executes the algorithm with arc number limit.
kpeter@696:     ///
kpeter@697:     /// This method runs the Bellman-Ford algorithm from the root node(s)
kpeter@697:     /// in order to compute the shortest path distance for each node
kpeter@697:     /// using only the paths consisting of at most \c num arcs.
kpeter@697:     ///
kpeter@697:     /// The algorithm computes
kpeter@697:     /// - the limited distance of each node from the root(s),
kpeter@697:     /// - the predecessor arc for each node.
kpeter@696:     ///
kpeter@696:     /// \warning The paths with limited arc number cannot be retrieved
kpeter@697:     /// easily with \ref path() or \ref predArc() functions. If you also
kpeter@697:     /// need the shortest paths and not only the distances, you should
kpeter@697:     /// store the \ref predMap() "predecessor map" after each iteration
kpeter@697:     /// and build the path manually.
kpeter@696:     ///
kpeter@697:     /// \pre init() must be called and at least one root node should be
kpeter@697:     /// added with addSource() before using this function. 
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@697:     /// \brief Runs the algorithm from the given root node.
kpeter@696:     ///    
kpeter@697:     /// This method runs the Bellman-Ford algorithm from the given root
kpeter@697:     /// node \c s in order to compute the shortest path to each node.
kpeter@696:     ///
kpeter@697:     /// The algorithm computes
kpeter@697:     /// - the shortest path tree (forest),
kpeter@697:     /// - the distance of each node from the root(s).
kpeter@697:     ///
kpeter@697:     /// \note bf.run(s) is just a shortcut of the following code.
kpeter@697:     /// \code
kpeter@697:     ///   bf.init();
kpeter@697:     ///   bf.addSource(s);
kpeter@697:     ///   bf.start();
kpeter@697:     /// \endcode
kpeter@696:     void run(Node s) {
kpeter@696:       init();
kpeter@696:       addSource(s);
kpeter@696:       start();
kpeter@696:     }
kpeter@696:     
kpeter@697:     /// \brief Runs the algorithm from the given root node with arc
kpeter@697:     /// number limit.
kpeter@696:     ///    
kpeter@697:     /// This method runs the Bellman-Ford algorithm from the given root
kpeter@697:     /// node \c s in order to compute the shortest path distance for each
kpeter@697:     /// node using only the paths consisting of at most \c num arcs.
kpeter@696:     ///
kpeter@697:     /// The algorithm computes
kpeter@697:     /// - the limited distance of each node from the root(s),
kpeter@697:     /// - the predecessor arc for each node.
kpeter@697:     ///
kpeter@697:     /// \warning The paths with limited arc number cannot be retrieved
kpeter@697:     /// easily with \ref path() or \ref predArc() functions. If you also
kpeter@697:     /// need the shortest paths and not only the distances, you should
kpeter@697:     /// store the \ref predMap() "predecessor map" after each iteration
kpeter@697:     /// and build the path manually.
kpeter@697:     ///
kpeter@697:     /// \note bf.run(s, num) is just a shortcut of the following code.
kpeter@697:     /// \code
kpeter@697:     ///   bf.init();
kpeter@697:     ///   bf.addSource(s);
kpeter@697:     ///   bf.limitedStart(num);
kpeter@697:     /// \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@697:     /// \brief LEMON iterator for getting the active nodes.
kpeter@696:     ///
kpeter@697:     /// This class provides a common style LEMON iterator that traverses
kpeter@697:     /// the active nodes of the Bellman-Ford algorithm after the last
kpeter@697:     /// phase. These nodes should be checked in the next phase to
kpeter@697:     /// find augmenting arcs outgoing from them.
kpeter@696:     class ActiveIt {
kpeter@696:     public:
kpeter@696: 
kpeter@696:       /// \brief Constructor.
kpeter@696:       ///
kpeter@697:       /// Constructor for getting the active nodes of the given BellmanFord
kpeter@697:       /// instance. 
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@697:       /// \brief Conversion to \c Node.
kpeter@696:       ///
kpeter@697:       /// Conversion to \c 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@697:     
kpeter@697:     /// \name Query Functions
kpeter@697:     /// The result of the Bellman-Ford algorithm can be obtained using these
kpeter@697:     /// functions.\n
kpeter@697:     /// Either \ref run() or \ref init() should be called before using them.
kpeter@697:     
kpeter@697:     ///@{
kpeter@696: 
kpeter@697:     /// \brief The shortest path to the given node.
kpeter@697:     ///    
kpeter@697:     /// Gives back the shortest path to the given node from the root(s).
kpeter@697:     ///
kpeter@697:     /// \warning \c t should be reached from the root(s).
kpeter@697:     ///
kpeter@697:     /// \pre Either \ref run() or \ref init() must be called before
kpeter@697:     /// using this function.
kpeter@697:     Path path(Node t) const
kpeter@697:     {
kpeter@697:       return Path(*_gr, *_pred, t);
kpeter@697:     }
kpeter@697: 	  
kpeter@697:     /// \brief The distance of the given node from the root(s).
kpeter@697:     ///
kpeter@697:     /// Returns the distance of the given node from the root(s).
kpeter@697:     ///
kpeter@697:     /// \warning If node \c v is not reached from the root(s), then
kpeter@697:     /// the return value of this function is undefined.
kpeter@697:     ///
kpeter@697:     /// \pre Either \ref run() or \ref init() must be called before
kpeter@697:     /// using this function.
kpeter@697:     Value dist(Node v) const { return (*_dist)[v]; }
kpeter@696: 
kpeter@697:     /// \brief Returns the 'previous arc' of the shortest path tree for
kpeter@697:     /// the given node.
kpeter@697:     ///
kpeter@697:     /// This function returns the 'previous arc' of the shortest path
kpeter@697:     /// tree for node \c v, i.e. it returns the last arc of a
kpeter@697:     /// shortest path from a root to \c v. It is \c INVALID if \c v
kpeter@697:     /// is not reached from the root(s) or if \c v is a root.
kpeter@697:     ///
kpeter@697:     /// The shortest path tree used here is equal to the shortest path
kpeter@786:     /// tree used in \ref predNode() and \ref predMap().
kpeter@697:     ///
kpeter@697:     /// \pre Either \ref run() or \ref init() must be called before
kpeter@697:     /// using this function.
kpeter@697:     Arc predArc(Node v) const { return (*_pred)[v]; }
kpeter@697: 
kpeter@697:     /// \brief Returns the 'previous node' of the shortest path tree for
kpeter@697:     /// the given node.
kpeter@697:     ///
kpeter@697:     /// This function returns the 'previous node' of the shortest path
kpeter@697:     /// tree for node \c v, i.e. it returns the last but one node of
kpeter@697:     /// a shortest path from a root to \c v. It is \c INVALID if \c v
kpeter@697:     /// is not reached from the root(s) or if \c v is a root.
kpeter@697:     ///
kpeter@697:     /// The shortest path tree used here is equal to the shortest path
kpeter@786:     /// tree used in \ref predArc() and \ref predMap().
kpeter@697:     ///
kpeter@697:     /// \pre Either \ref run() or \ref init() must be called before
kpeter@697:     /// using this function.
kpeter@697:     Node predNode(Node v) const { 
kpeter@697:       return (*_pred)[v] == INVALID ? INVALID : _gr->source((*_pred)[v]); 
kpeter@697:     }
kpeter@697:     
kpeter@697:     /// \brief Returns a const reference to the node map that stores the
kpeter@697:     /// distances of the nodes.
kpeter@697:     ///
kpeter@697:     /// Returns a const reference to the node map that stores the distances
kpeter@697:     /// of the nodes calculated by the algorithm.
kpeter@697:     ///
kpeter@697:     /// \pre Either \ref run() or \ref init() must be called before
kpeter@697:     /// using this function.
kpeter@697:     const DistMap &distMap() const { return *_dist;}
kpeter@697:  
kpeter@697:     /// \brief Returns a const reference to the node map that stores the
kpeter@697:     /// predecessor arcs.
kpeter@697:     ///
kpeter@697:     /// Returns a const reference to the node map that stores the predecessor
kpeter@697:     /// arcs, which form the shortest path tree (forest).
kpeter@697:     ///
kpeter@697:     /// \pre Either \ref run() or \ref init() must be called before
kpeter@697:     /// using this function.
kpeter@697:     const PredMap &predMap() const { return *_pred; }
kpeter@697:  
kpeter@697:     /// \brief Checks if a node is reached from the root(s).
kpeter@697:     ///
kpeter@697:     /// Returns \c true if \c v is reached from the root(s).
kpeter@697:     ///
kpeter@697:     /// \pre Either \ref run() or \ref init() must be called before
kpeter@697:     /// using this function.
kpeter@697:     bool reached(Node v) const {
kpeter@697:       return (*_dist)[v] != OperationTraits::infinity();
kpeter@696:     }
kpeter@696: 
kpeter@699:     /// \brief Gives back a negative cycle.
kpeter@699:     ///    
kpeter@699:     /// This function gives back a directed cycle with negative total
kpeter@699:     /// length if the algorithm has already found one.
kpeter@699:     /// Otherwise it gives back an empty path.
kpeter@781:     lemon::Path<Digraph> negativeCycle() const {
kpeter@699:       typename Digraph::template NodeMap<int> state(*_gr, -1);
kpeter@699:       lemon::Path<Digraph> cycle;
kpeter@699:       for (int i = 0; i < int(_process.size()); ++i) {
kpeter@699:         if (state[_process[i]] != -1) continue;
kpeter@699:         for (Node v = _process[i]; (*_pred)[v] != INVALID;
kpeter@699:              v = _gr->source((*_pred)[v])) {
kpeter@699:           if (state[v] == i) {
kpeter@699:             cycle.addFront((*_pred)[v]);
kpeter@699:             for (Node u = _gr->source((*_pred)[v]); u != v;
kpeter@699:                  u = _gr->source((*_pred)[u])) {
kpeter@699:               cycle.addFront((*_pred)[u]);
kpeter@699:             }
kpeter@699:             return cycle;
kpeter@699:           }
kpeter@699:           else if (state[v] >= 0) {
kpeter@699:             break;
kpeter@699:           }
kpeter@699:           state[v] = i;
kpeter@699:         }
kpeter@699:       }
kpeter@699:       return cycle;
kpeter@699:     }
kpeter@696:     
kpeter@696:     ///@}
kpeter@696:   };
kpeter@696:  
kpeter@697:   /// \brief Default traits class of bellmanFord() function.
kpeter@696:   ///
kpeter@697:   /// Default traits class of bellmanFord() function.
kpeter@697:   /// \tparam GR The type of the digraph.
kpeter@697:   /// \tparam LEN The type of the length map.
kpeter@697:   template <typename GR, typename LEN>
kpeter@696:   struct BellmanFordWizardDefaultTraits {
kpeter@697:     /// The type of the digraph the algorithm runs on. 
kpeter@697:     typedef GR 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@697:     typedef LEN LengthMap;
kpeter@696: 
kpeter@697:     /// The type of the arc lengths.
kpeter@697:     typedef typename LEN::Value Value;
kpeter@696: 
kpeter@696:     /// \brief Operation traits for Bellman-Ford algorithm.
kpeter@696:     ///
kpeter@697:     /// It defines the used operations and the infinity value for the
kpeter@697:     /// given \c Value type.
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@697:     /// The type of the map that stores the last arcs of the shortest paths.
kpeter@697:     /// It must conform to the \ref concepts::WriteMap "WriteMap" concept.
kpeter@697:     typedef typename GR::template NodeMap<typename GR::Arc> PredMap;
kpeter@696: 
kpeter@697:     /// \brief Instantiates a \c PredMap.
kpeter@696:     /// 
kpeter@697:     /// This function instantiates a \ref PredMap.
kpeter@697:     /// \param g is the digraph to which we would like to define the
kpeter@697:     /// \ref PredMap.
kpeter@697:     static PredMap *createPredMap(const GR &g) {
kpeter@697:       return new PredMap(g);
kpeter@696:     }
kpeter@697: 
kpeter@697:     /// \brief The type of the map that stores the distances of the nodes.
kpeter@696:     ///
kpeter@697:     /// The type of the map that stores the distances of the nodes.
kpeter@697:     /// It must conform to the \ref concepts::WriteMap "WriteMap" concept.
kpeter@697:     typedef typename GR::template NodeMap<Value> DistMap;
kpeter@697: 
kpeter@697:     /// \brief Instantiates a \c DistMap.
kpeter@696:     ///
kpeter@696:     /// This function instantiates a \ref DistMap. 
kpeter@697:     /// \param g is the digraph to which we would like to define the
kpeter@697:     /// \ref DistMap.
kpeter@697:     static DistMap *createDistMap(const GR &g) {
kpeter@697:       return new DistMap(g);
kpeter@696:     }
kpeter@697: 
kpeter@697:     ///The type of the shortest paths.
kpeter@697: 
kpeter@697:     ///The type of the shortest paths.
kpeter@697:     ///It must meet the \ref concepts::Path "Path" concept.
kpeter@697:     typedef lemon::Path<Digraph> Path;
kpeter@696:   };
kpeter@696:   
kpeter@697:   /// \brief Default traits class used by BellmanFordWizard.
kpeter@696:   ///
kpeter@697:   /// Default traits class used by BellmanFordWizard.
kpeter@697:   /// \tparam GR The type of the digraph.
kpeter@697:   /// \tparam LEN The type of the length map.
kpeter@697:   template <typename GR, typename LEN>
kpeter@696:   class BellmanFordWizardBase 
kpeter@697:     : public BellmanFordWizardDefaultTraits<GR, LEN> {
kpeter@696: 
kpeter@697:     typedef BellmanFordWizardDefaultTraits<GR, LEN> Base;
kpeter@696:   protected:
kpeter@697:     // Type of the nodes in the digraph.
kpeter@696:     typedef typename Base::Digraph::Node Node;
kpeter@696: 
kpeter@697:     // Pointer to the underlying digraph.
kpeter@696:     void *_graph;
kpeter@697:     // Pointer to the length map
kpeter@696:     void *_length;
kpeter@697:     // Pointer to the map of predecessors arcs.
kpeter@696:     void *_pred;
kpeter@697:     // Pointer to the map of distances.
kpeter@696:     void *_dist;
kpeter@697:     //Pointer to the shortest path to the target node.
kpeter@697:     void *_path;
kpeter@697:     //Pointer to the distance of the target node.
kpeter@697:     void *_di;
kpeter@696: 
kpeter@696:     public:
kpeter@696:     /// Constructor.
kpeter@696:     
kpeter@697:     /// This constructor does not require parameters, it initiates
kpeter@697:     /// all of the attributes to default values \c 0.
kpeter@697:     BellmanFordWizardBase() :
kpeter@697:       _graph(0), _length(0), _pred(0), _dist(0), _path(0), _di(0) {}
kpeter@696: 
kpeter@696:     /// Constructor.
kpeter@696:     
kpeter@697:     /// This constructor requires two parameters,
kpeter@697:     /// others are initiated to \c 0.
kpeter@697:     /// \param gr The digraph the algorithm runs on.
kpeter@697:     /// \param len The length map.
kpeter@697:     BellmanFordWizardBase(const GR& gr, 
kpeter@697: 			  const LEN& len) :
kpeter@697:       _graph(reinterpret_cast<void*>(const_cast<GR*>(&gr))), 
kpeter@697:       _length(reinterpret_cast<void*>(const_cast<LEN*>(&len))), 
kpeter@697:       _pred(0), _dist(0), _path(0), _di(0) {}
kpeter@696: 
kpeter@696:   };
kpeter@696:   
kpeter@697:   /// \brief Auxiliary class for the function-type interface of the
kpeter@697:   /// \ref BellmanFord "Bellman-Ford" algorithm.
kpeter@697:   ///
kpeter@697:   /// This auxiliary class is created to implement the
kpeter@697:   /// \ref bellmanFord() "function-type interface" of the
kpeter@697:   /// \ref BellmanFord "Bellman-Ford" algorithm.
kpeter@697:   /// It does not have own \ref run() method, it uses the
kpeter@697:   /// functions and features of the plain \ref BellmanFord.
kpeter@697:   ///
kpeter@697:   /// This class should only be used through the \ref bellmanFord()
kpeter@697:   /// function, which makes it easier to use the algorithm.
kpeter@825:   ///
kpeter@825:   /// \tparam TR The traits class that defines various types used by the
kpeter@825:   /// algorithm.
kpeter@697:   template<class TR>
kpeter@697:   class BellmanFordWizard : public TR {
kpeter@697:     typedef TR Base;
kpeter@696: 
kpeter@697:     typedef typename TR::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@697:     typedef typename TR::LengthMap LengthMap;
kpeter@696:     typedef typename LengthMap::Value Value;
kpeter@697:     typedef typename TR::PredMap PredMap;
kpeter@697:     typedef typename TR::DistMap DistMap;
kpeter@697:     typedef typename TR::Path Path;
kpeter@696: 
kpeter@696:   public:
kpeter@696:     /// Constructor.
kpeter@697:     BellmanFordWizard() : TR() {}
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@697:     /// \param gr The digraph the algorithm runs on.
kpeter@697:     /// \param len The length map.
kpeter@697:     BellmanFordWizard(const Digraph& gr, const LengthMap& len) 
kpeter@697:       : TR(gr, len) {}
kpeter@696: 
kpeter@696:     /// \brief Copy constructor
kpeter@697:     BellmanFordWizard(const TR &b) : TR(b) {}
kpeter@696: 
kpeter@696:     ~BellmanFordWizard() {}
kpeter@696: 
kpeter@697:     /// \brief Runs the Bellman-Ford algorithm from the given source node.
kpeter@696:     ///    
kpeter@697:     /// This method runs the Bellman-Ford algorithm from the given source
kpeter@697:     /// node in order to compute the shortest path to each node.
kpeter@697:     void run(Node s) {
kpeter@697:       BellmanFord<Digraph,LengthMap,TR> 
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@697:       bf.run(s);
kpeter@696:     }
kpeter@696: 
kpeter@697:     /// \brief Runs the Bellman-Ford algorithm to find the shortest path
kpeter@697:     /// between \c s and \c t.
kpeter@696:     ///
kpeter@697:     /// This method runs the Bellman-Ford algorithm from node \c s
kpeter@697:     /// in order to compute the shortest path to node \c t.
kpeter@697:     /// Actually, it computes the shortest path to each node, but using
kpeter@697:     /// this function you can retrieve the distance and the shortest path
kpeter@697:     /// for a single target node easier.
kpeter@697:     ///
kpeter@697:     /// \return \c true if \c t is reachable form \c s.
kpeter@697:     bool run(Node s, Node t) {
kpeter@697:       BellmanFord<Digraph,LengthMap,TR>
kpeter@697:         bf(*reinterpret_cast<const Digraph*>(Base::_graph),
kpeter@697:            *reinterpret_cast<const LengthMap*>(Base::_length));
kpeter@697:       if (Base::_pred) bf.predMap(*reinterpret_cast<PredMap*>(Base::_pred));
kpeter@697:       if (Base::_dist) bf.distMap(*reinterpret_cast<DistMap*>(Base::_dist));
kpeter@697:       bf.run(s);
kpeter@697:       if (Base::_path) *reinterpret_cast<Path*>(Base::_path) = bf.path(t);
kpeter@697:       if (Base::_di) *reinterpret_cast<Value*>(Base::_di) = bf.dist(t);
kpeter@697:       return bf.reached(t);
kpeter@696:     }
kpeter@696: 
kpeter@696:     template<class T>
kpeter@697:     struct SetPredMapBase : public Base {
kpeter@696:       typedef T PredMap;
kpeter@696:       static PredMap *createPredMap(const Digraph &) { return 0; };
kpeter@697:       SetPredMapBase(const TR &b) : TR(b) {}
kpeter@696:     };
kpeter@696:     
kpeter@697:     /// \brief \ref named-templ-param "Named parameter" for setting
kpeter@697:     /// the predecessor map.
kpeter@696:     ///
kpeter@697:     /// \ref named-templ-param "Named parameter" for setting
kpeter@697:     /// the map that stores the predecessor arcs of the nodes.
kpeter@696:     template<class T>
kpeter@697:     BellmanFordWizard<SetPredMapBase<T> > predMap(const T &t) {
kpeter@696:       Base::_pred=reinterpret_cast<void*>(const_cast<T*>(&t));
kpeter@697:       return BellmanFordWizard<SetPredMapBase<T> >(*this);
kpeter@696:     }
kpeter@696:     
kpeter@696:     template<class T>
kpeter@697:     struct SetDistMapBase : public Base {
kpeter@696:       typedef T DistMap;
kpeter@696:       static DistMap *createDistMap(const Digraph &) { return 0; };
kpeter@697:       SetDistMapBase(const TR &b) : TR(b) {}
kpeter@696:     };
kpeter@696:     
kpeter@697:     /// \brief \ref named-templ-param "Named parameter" for setting
kpeter@697:     /// the distance map.
kpeter@696:     ///
kpeter@697:     /// \ref named-templ-param "Named parameter" for setting
kpeter@697:     /// the map that stores the distances of the nodes calculated
kpeter@697:     /// by the algorithm.
kpeter@696:     template<class T>
kpeter@697:     BellmanFordWizard<SetDistMapBase<T> > distMap(const T &t) {
kpeter@696:       Base::_dist=reinterpret_cast<void*>(const_cast<T*>(&t));
kpeter@697:       return BellmanFordWizard<SetDistMapBase<T> >(*this);
kpeter@696:     }
kpeter@696: 
kpeter@696:     template<class T>
kpeter@697:     struct SetPathBase : public Base {
kpeter@697:       typedef T Path;
kpeter@697:       SetPathBase(const TR &b) : TR(b) {}
kpeter@696:     };
kpeter@697: 
kpeter@697:     /// \brief \ref named-func-param "Named parameter" for getting
kpeter@697:     /// the shortest path to the target node.
kpeter@696:     ///
kpeter@697:     /// \ref named-func-param "Named parameter" for getting
kpeter@697:     /// the shortest path to the target node.
kpeter@697:     template<class T>
kpeter@697:     BellmanFordWizard<SetPathBase<T> > path(const T &t)
kpeter@697:     {
kpeter@697:       Base::_path=reinterpret_cast<void*>(const_cast<T*>(&t));
kpeter@697:       return BellmanFordWizard<SetPathBase<T> >(*this);
kpeter@697:     }
kpeter@697: 
kpeter@697:     /// \brief \ref named-func-param "Named parameter" for getting
kpeter@697:     /// the distance of the target node.
kpeter@696:     ///
kpeter@697:     /// \ref named-func-param "Named parameter" for getting
kpeter@697:     /// the distance of the target node.
kpeter@697:     BellmanFordWizard dist(const Value &d)
kpeter@697:     {
kpeter@697:       Base::_di=reinterpret_cast<void*>(const_cast<Value*>(&d));
kpeter@696:       return *this;
kpeter@696:     }
kpeter@696:     
kpeter@696:   };
kpeter@696:   
kpeter@697:   /// \brief Function type interface for the \ref BellmanFord "Bellman-Ford"
kpeter@697:   /// algorithm.
kpeter@696:   ///
kpeter@696:   /// \ingroup shortest_path
kpeter@697:   /// Function type interface for the \ref BellmanFord "Bellman-Ford"
kpeter@697:   /// 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@697:   /// The following examples show how to use these parameters.
kpeter@697:   /// \code
kpeter@697:   ///   // Compute shortest path from node s to each node
kpeter@697:   ///   bellmanFord(g,length).predMap(preds).distMap(dists).run(s);
kpeter@697:   ///
kpeter@697:   ///   // Compute shortest path from s to t
kpeter@697:   ///   bool reached = bellmanFord(g,length).path(p).dist(d).run(s,t);
kpeter@697:   /// \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@697:   template<typename GR, typename LEN>
kpeter@697:   BellmanFordWizard<BellmanFordWizardBase<GR,LEN> >
kpeter@697:   bellmanFord(const GR& digraph,
kpeter@697: 	      const LEN& length)
kpeter@697:   {
kpeter@697:     return BellmanFordWizard<BellmanFordWizardBase<GR,LEN> >(digraph, length);
kpeter@696:   }
kpeter@696: 
kpeter@696: } //END OF NAMESPACE LEMON
kpeter@696: 
kpeter@696: #endif
kpeter@696: