alpar@877: /* -*- mode: C++; indent-tabs-mode: nil; -*-
kpeter@696: *
alpar@877: * This file is a part of LEMON, a generic C++ optimization library.
kpeter@696: *
alpar@877: * Copyright (C) 2003-2010
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:
alpar@879: /// \brief Default OperationTraits for the BellmanFord algorithm class.
alpar@877: ///
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 <
alpar@877: typename V,
kpeter@697: bool has_inf = std::numeric_limits<V>::has_infinity>
kpeter@696: struct BellmanFordDefaultOperationTraits {
alpar@879: /// \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: };
alpar@877:
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 {
alpar@877: /// 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.
alpar@879: /// \see BellmanFordDefaultOperationTraits
kpeter@696: typedef BellmanFordDefaultOperationTraits<Value> OperationTraits;
alpar@877:
alpar@877: /// \brief The type of the map that stores the last arcs of the
kpeter@696: /// shortest paths.
alpar@877: ///
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.
alpar@877: ///
alpar@877: /// 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: ///
alpar@877: /// This function instantiates a \ref DistMap.
alpar@877: /// \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: };
alpar@877:
kpeter@696: /// \brief %BellmanFord algorithm class.
kpeter@696: ///
kpeter@696: /// \ingroup shortest_path
alpar@877: /// 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
alpar@877: /// \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;
alpar@877:
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) {
alpar@877: _local_pred = true;
alpar@877: _pred = Traits::createPredMap(*_gr);
kpeter@696: }
kpeter@696: if(!_dist) {
alpar@877: _local_dist = true;
alpar@877: _dist = Traits::createDistMap(*_gr);
kpeter@696: }
kpeter@804: if(!_mask) {
kpeter@804: _mask = new MaskMap(*_gr);
kpeter@804: }
kpeter@696: }
alpar@877:
kpeter@696: public :
alpar@877:
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>
alpar@877: struct SetPredMap
kpeter@697: : public BellmanFord< Digraph, LengthMap, SetPredMapTraits<T> > {
kpeter@697: typedef BellmanFord< Digraph, LengthMap, SetPredMapTraits<T> > Create;
kpeter@696: };
alpar@877:
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>
alpar@877: 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: };
alpar@877:
alpar@877: /// \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: };
alpar@877:
kpeter@696: ///@}
kpeter@696:
kpeter@696: protected:
alpar@877:
kpeter@696: BellmanFord() {}
kpeter@696:
alpar@877: public:
alpar@877:
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) {}
alpar@877:
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 = ↦
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) {
alpar@877: delete _pred;
alpar@877: _local_pred=false;
kpeter@696: }
kpeter@697: _pred = ↦
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) {
alpar@877: delete _dist;
alpar@877: _local_dist=false;
kpeter@696: }
kpeter@697: _dist = ↦
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.
alpar@877: ///
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) {
alpar@877: _pred->set(it, INVALID);
alpar@877: _dist->set(it, value);
kpeter@696: }
kpeter@696: _process.clear();
kpeter@696: if (OperationTraits::less(value, OperationTraits::infinity())) {
alpar@877: for (NodeIt it(*_gr); it != INVALID; ++it) {
alpar@877: _process.push_back(it);
alpar@877: _mask->set(it, true);
alpar@877: }
kpeter@804: } else {
alpar@877: for (NodeIt it(*_gr); it != INVALID; ++it) {
alpar@877: _mask->set(it, false);
alpar@877: }
kpeter@696: }
kpeter@696: }
alpar@877:
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]) {
alpar@877: _process.push_back(source);
alpar@877: _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) {
alpar@877: _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) {
alpar@877: values[i] = (*_dist)[_process[i]];
kpeter@696: }
kpeter@696: for (int i = 0; i < int(_process.size()); ++i) {
alpar@877: for (OutArcIt it(*_gr, _process[i]); it != INVALID; ++it) {
alpar@877: Node target = _gr->target(it);
alpar@877: Value relaxed = OperationTraits::plus(values[i], (*_length)[it]);
alpar@877: if (OperationTraits::less(relaxed, (*_dist)[target])) {
alpar@877: _pred->set(target, it);
alpar@877: _dist->set(target, relaxed);
alpar@877: if (!(*_mask)[target]) {
alpar@877: _mask->set(target, true);
alpar@877: nextProcess.push_back(target);
alpar@877: }
alpar@877: }
alpar@877: }
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) {
alpar@877: _mask->set(_process[i], false);
kpeter@696: }
kpeter@696: std::vector<Node> nextProcess;
kpeter@696: for (int i = 0; i < int(_process.size()); ++i) {
alpar@877: for (OutArcIt it(*_gr, _process[i]); it != INVALID; ++it) {
alpar@877: Node target = _gr->target(it);
alpar@877: Value relaxed =
alpar@877: OperationTraits::plus((*_dist)[_process[i]], (*_length)[it]);
alpar@877: if (OperationTraits::less(relaxed, (*_dist)[target])) {
alpar@877: _pred->set(target, it);
alpar@877: _dist->set(target, relaxed);
alpar@877: if (!(*_mask)[target]) {
alpar@877: _mask->set(target, true);
alpar@877: nextProcess.push_back(target);
alpar@877: }
alpar@877: }
alpar@877: }
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) {
alpar@877: 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: ///
alpar@877: /// The algorithm computes
kpeter@697: /// - the shortest path tree (forest),
kpeter@697: /// - the distance of each node from the root(s).
alpar@877: ///
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
alpar@877: /// 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) {
alpar@877: 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
alpar@877: /// added with addSource() before using this function.
kpeter@696: void limitedStart(int num) {
kpeter@696: for (int i = 0; i < num; ++i) {
alpar@877: if (processNextRound()) break;
kpeter@696: }
kpeter@696: }
alpar@877:
kpeter@697: /// \brief Runs the algorithm from the given root node.
alpar@877: ///
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: }
alpar@877:
kpeter@697: /// \brief Runs the algorithm from the given root node with arc
kpeter@697: /// number limit.
alpar@877: ///
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: }
alpar@877:
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
alpar@877: /// 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.
alpar@877: 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;
alpar@877: return *this;
kpeter@696: }
kpeter@696:
alpar@877: bool operator==(const ActiveIt& it) const {
alpar@877: return static_cast<Node>(*this) == static_cast<Node>(it);
kpeter@696: }
alpar@877: bool operator!=(const ActiveIt& it) const {
alpar@877: return static_cast<Node>(*this) != static_cast<Node>(it);
kpeter@696: }
alpar@877: bool operator<(const ActiveIt& it) const {
alpar@877: return static_cast<Node>(*this) < static_cast<Node>(it);
kpeter@696: }
alpar@877:
kpeter@696: private:
kpeter@696: const BellmanFord* _algorithm;
kpeter@696: int _index;
kpeter@696: };
alpar@877:
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.
alpar@877:
kpeter@697: ///@{
kpeter@696:
kpeter@697: /// \brief The shortest path to the given node.
alpar@877: ///
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: }
alpar@877:
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.
alpar@877: Node predNode(Node v) const {
alpar@877: return (*_pred)[v] == INVALID ? INVALID : _gr->source((*_pred)[v]);
kpeter@697: }
alpar@877:
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;}
alpar@877:
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; }
alpar@877:
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.
alpar@877: ///
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: }
alpar@877:
kpeter@696: ///@}
kpeter@696: };
alpar@877:
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 {
alpar@877: /// 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.
alpar@879: /// \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.
alpar@877: ///
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.
alpar@877: ///
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: ///
alpar@877: /// 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: };
alpar@877:
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>
alpar@877: 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.
alpar@877:
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.
alpar@877:
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.
alpar@877: BellmanFordWizardBase(const GR& gr,
alpar@877: const LEN& len) :
alpar@877: _graph(reinterpret_cast<void*>(const_cast<GR*>(&gr))),
alpar@877: _length(reinterpret_cast<void*>(const_cast<LEN*>(&len))),
kpeter@697: _pred(0), _dist(0), _path(0), _di(0) {}
kpeter@696:
kpeter@696: };
alpar@877:
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;
alpar@877:
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.
alpar@877: 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.
alpar@877: ///
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) {
alpar@877: BellmanFord<Digraph,LengthMap,TR>
alpar@877: 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: };
alpar@877:
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: }
alpar@877:
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: };
alpar@877:
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: }
alpar@877:
kpeter@696: };
alpar@877:
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: ///
alpar@877: /// This function also has several \ref named-templ-func-param
alpar@877: /// "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,
alpar@877: 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: