lemon/bellman_ford.h
author Balazs Dezso <deba@inf.elte.hu>
Fri, 25 Sep 2009 21:51:36 +0200
changeset 869 636dadefe1e6
parent 697 9496ed797f20
child 781 6f10c6ec5a21
child 786 e20173729589
permissions -rw-r--r--
Add fractional matching algorithms (#314)
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/* -*- C++ -*-
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 *
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 * This file is a part of LEMON, a generic C++ optimization library
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 *
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 * Copyright (C) 2003-2008
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 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
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 * (Egervary Research Group on Combinatorial Optimization, EGRES).
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 *
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 * Permission to use, modify and distribute this software is granted
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 * provided that this copyright notice appears in all copies. For
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 * precise terms see the accompanying LICENSE file.
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 *
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 * This software is provided "AS IS" with no warranty of any kind,
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 * express or implied, and with no claim as to its suitability for any
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 * purpose.
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 *
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 */
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#ifndef LEMON_BELLMAN_FORD_H
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#define LEMON_BELLMAN_FORD_H
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/// \ingroup shortest_path
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/// \file
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/// \brief Bellman-Ford algorithm.
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#include <lemon/bits/path_dump.h>
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#include <lemon/core.h>
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#include <lemon/error.h>
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#include <lemon/maps.h>
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#include <lemon/path.h>
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#include <limits>
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namespace lemon {
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  /// \brief Default OperationTraits for the BellmanFord algorithm class.
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  ///  
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  /// This operation traits class defines all computational operations
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  /// and constants that are used in the Bellman-Ford algorithm.
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  /// The default implementation is based on the \c numeric_limits class.
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  /// If the numeric type does not have infinity value, then the maximum
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  /// value is used as extremal infinity value.
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  template <
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    typename V, 
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    bool has_inf = std::numeric_limits<V>::has_infinity>
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  struct BellmanFordDefaultOperationTraits {
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    /// \e
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    typedef V Value;
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    /// \brief Gives back the zero value of the type.
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    static Value zero() {
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      return static_cast<Value>(0);
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    }
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    /// \brief Gives back the positive infinity value of the type.
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    static Value infinity() {
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      return std::numeric_limits<Value>::infinity();
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    }
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    /// \brief Gives back the sum of the given two elements.
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    static Value plus(const Value& left, const Value& right) {
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      return left + right;
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    }
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    /// \brief Gives back \c true only if the first value is less than
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    /// the second.
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    static bool less(const Value& left, const Value& right) {
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      return left < right;
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    }
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  };
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  template <typename V>
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  struct BellmanFordDefaultOperationTraits<V, false> {
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    typedef V Value;
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    static Value zero() {
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      return static_cast<Value>(0);
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    }
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    static Value infinity() {
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      return std::numeric_limits<Value>::max();
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    }
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    static Value plus(const Value& left, const Value& right) {
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      if (left == infinity() || right == infinity()) return infinity();
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      return left + right;
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    }
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    static bool less(const Value& left, const Value& right) {
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      return left < right;
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    }
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  };
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  /// \brief Default traits class of BellmanFord class.
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  ///
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  /// Default traits class of BellmanFord class.
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  /// \param GR The type of the digraph.
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  /// \param LEN The type of the length map.
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  template<typename GR, typename LEN>
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  struct BellmanFordDefaultTraits {
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    /// The type of the digraph the algorithm runs on. 
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    typedef GR Digraph;
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    /// \brief The type of the map that stores the arc lengths.
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    ///
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    /// The type of the map that stores the arc lengths.
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    /// It must conform to the \ref concepts::ReadMap "ReadMap" concept.
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    typedef LEN LengthMap;
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    /// The type of the arc lengths.
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    typedef typename LEN::Value Value;
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    /// \brief Operation traits for Bellman-Ford algorithm.
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    ///
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    /// It defines the used operations and the infinity value for the
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    /// given \c Value type.
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    /// \see BellmanFordDefaultOperationTraits
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    typedef BellmanFordDefaultOperationTraits<Value> OperationTraits;
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    /// \brief The type of the map that stores the last arcs of the 
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    /// shortest paths.
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    /// 
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    /// The type of the map that stores the last
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    /// arcs of the shortest paths.
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    /// It must conform to the \ref concepts::WriteMap "WriteMap" concept.
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    typedef typename GR::template NodeMap<typename GR::Arc> PredMap;
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    /// \brief Instantiates a \c PredMap.
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    /// 
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    /// This function instantiates a \ref PredMap. 
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    /// \param g is the digraph to which we would like to define the
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    /// \ref PredMap.
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    static PredMap *createPredMap(const GR& g) {
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      return new PredMap(g);
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    }
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    /// \brief The type of the map that stores the distances of the nodes.
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    ///
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    /// The type of the map that stores the distances of the nodes.
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    /// It must conform to the \ref concepts::WriteMap "WriteMap" concept.
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    typedef typename GR::template NodeMap<typename LEN::Value> DistMap;
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    /// \brief Instantiates a \c DistMap.
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    ///
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    /// This function instantiates a \ref DistMap. 
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    /// \param g is the digraph to which we would like to define the 
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    /// \ref DistMap.
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    static DistMap *createDistMap(const GR& g) {
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      return new DistMap(g);
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    }
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  };
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  /// \brief %BellmanFord algorithm class.
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  ///
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  /// \ingroup shortest_path
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  /// This class provides an efficient implementation of the Bellman-Ford 
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  /// algorithm. The maximum time complexity of the algorithm is
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  /// <tt>O(ne)</tt>.
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  ///
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  /// The Bellman-Ford algorithm solves the single-source shortest path
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  /// problem when the arcs can have negative lengths, but the digraph
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  /// should not contain directed cycles with negative total length.
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  /// If all arc costs are non-negative, consider to use the Dijkstra
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  /// algorithm instead, since it is more efficient.
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  ///
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  /// The arc lengths are passed to the algorithm using a
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  /// \ref concepts::ReadMap "ReadMap", so it is easy to change it to any 
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  /// kind of length. The type of the length values is determined by the
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  /// \ref concepts::ReadMap::Value "Value" type of the length map.
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  ///
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  /// There is also a \ref bellmanFord() "function-type interface" for the
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  /// Bellman-Ford algorithm, which is convenient in the simplier cases and
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  /// it can be used easier.
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  ///
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  /// \tparam GR The type of the digraph the algorithm runs on.
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  /// The default type is \ref ListDigraph.
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  /// \tparam LEN A \ref concepts::ReadMap "readable" arc map that specifies
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  /// the lengths of the arcs. The default map type is
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  /// \ref concepts::Digraph::ArcMap "GR::ArcMap<int>".
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#ifdef DOXYGEN
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  template <typename GR, typename LEN, typename TR>
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#else
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  template <typename GR=ListDigraph,
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            typename LEN=typename GR::template ArcMap<int>,
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            typename TR=BellmanFordDefaultTraits<GR,LEN> >
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#endif
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  class BellmanFord {
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  public:
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    ///The type of the underlying digraph.
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    typedef typename TR::Digraph Digraph;
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    /// \brief The type of the arc lengths.
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    typedef typename TR::LengthMap::Value Value;
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    /// \brief The type of the map that stores the arc lengths.
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    typedef typename TR::LengthMap LengthMap;
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    /// \brief The type of the map that stores the last
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    /// arcs of the shortest paths.
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    typedef typename TR::PredMap PredMap;
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    /// \brief The type of the map that stores the distances of the nodes.
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    typedef typename TR::DistMap DistMap;
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    /// The type of the paths.
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    typedef PredMapPath<Digraph, PredMap> Path;
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    ///\brief The \ref BellmanFordDefaultOperationTraits
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    /// "operation traits class" of the algorithm.
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    typedef typename TR::OperationTraits OperationTraits;
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    ///The \ref BellmanFordDefaultTraits "traits class" of the algorithm.
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    typedef TR Traits;
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  private:
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    typedef typename Digraph::Node Node;
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    typedef typename Digraph::NodeIt NodeIt;
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    typedef typename Digraph::Arc Arc;
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    typedef typename Digraph::OutArcIt OutArcIt;
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    // Pointer to the underlying digraph.
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    const Digraph *_gr;
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    // Pointer to the length map
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    const LengthMap *_length;
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    // Pointer to the map of predecessors arcs.
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    PredMap *_pred;
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    // Indicates if _pred is locally allocated (true) or not.
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    bool _local_pred;
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    // Pointer to the map of distances.
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    DistMap *_dist;
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    // Indicates if _dist is locally allocated (true) or not.
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    bool _local_dist;
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    typedef typename Digraph::template NodeMap<bool> MaskMap;
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    MaskMap *_mask;
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    std::vector<Node> _process;
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    // Creates the maps if necessary.
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    void create_maps() {
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      if(!_pred) {
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	_local_pred = true;
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	_pred = Traits::createPredMap(*_gr);
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      }
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      if(!_dist) {
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	_local_dist = true;
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	_dist = Traits::createDistMap(*_gr);
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      }
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      _mask = new MaskMap(*_gr, false);
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    }
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  public :
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    typedef BellmanFord Create;
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    /// \name Named Template Parameters
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    ///@{
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    template <class T>
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    struct SetPredMapTraits : public Traits {
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      typedef T PredMap;
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      static PredMap *createPredMap(const Digraph&) {
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        LEMON_ASSERT(false, "PredMap is not initialized");
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        return 0; // ignore warnings
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      }
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    };
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    /// \brief \ref named-templ-param "Named parameter" for setting
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    /// \c PredMap type.
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    ///
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    /// \ref named-templ-param "Named parameter" for setting
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    /// \c PredMap type.
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    /// It must conform to the \ref concepts::WriteMap "WriteMap" concept.
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    template <class T>
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    struct SetPredMap 
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      : public BellmanFord< Digraph, LengthMap, SetPredMapTraits<T> > {
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      typedef BellmanFord< Digraph, LengthMap, SetPredMapTraits<T> > Create;
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    };
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    template <class T>
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    struct SetDistMapTraits : public Traits {
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      typedef T DistMap;
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      static DistMap *createDistMap(const Digraph&) {
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        LEMON_ASSERT(false, "DistMap is not initialized");
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        return 0; // ignore warnings
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      }
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    };
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    /// \brief \ref named-templ-param "Named parameter" for setting
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    /// \c DistMap type.
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    ///
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    /// \ref named-templ-param "Named parameter" for setting
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    /// \c DistMap type.
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    /// It must conform to the \ref concepts::WriteMap "WriteMap" concept.
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    template <class T>
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    struct SetDistMap 
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      : public BellmanFord< Digraph, LengthMap, SetDistMapTraits<T> > {
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      typedef BellmanFord< Digraph, LengthMap, SetDistMapTraits<T> > Create;
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    };
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    template <class T>
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    struct SetOperationTraitsTraits : public Traits {
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      typedef T OperationTraits;
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    };
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    /// \brief \ref named-templ-param "Named parameter" for setting 
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    /// \c OperationTraits type.
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    ///
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    /// \ref named-templ-param "Named parameter" for setting
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    /// \c OperationTraits type.
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    /// For more information see \ref BellmanFordDefaultOperationTraits.
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    template <class T>
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    struct SetOperationTraits
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      : public BellmanFord< Digraph, LengthMap, SetOperationTraitsTraits<T> > {
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      typedef BellmanFord< Digraph, LengthMap, SetOperationTraitsTraits<T> >
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      Create;
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    };
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    ///@}
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  protected:
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    BellmanFord() {}
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  public:      
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    /// \brief Constructor.
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    ///
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    /// Constructor.
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    /// \param g The digraph the algorithm runs on.
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    /// \param length The length map used by the algorithm.
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    BellmanFord(const Digraph& g, const LengthMap& length) :
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      _gr(&g), _length(&length),
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      _pred(0), _local_pred(false),
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      _dist(0), _local_dist(false), _mask(0) {}
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    ///Destructor.
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    ~BellmanFord() {
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      if(_local_pred) delete _pred;
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      if(_local_dist) delete _dist;
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      if(_mask) delete _mask;
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    }
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    /// \brief Sets the length map.
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    ///
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    /// Sets the length map.
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    /// \return <tt>(*this)</tt>
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    BellmanFord &lengthMap(const LengthMap &map) {
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      _length = &map;
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      return *this;
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    }
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    /// \brief Sets the map that stores the predecessor arcs.
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    ///
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    /// Sets the map that stores the predecessor arcs.
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    /// If you don't use this function before calling \ref run()
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    /// or \ref init(), an instance will be allocated automatically.
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    /// The destructor deallocates this automatically allocated map,
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    /// of course.
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    /// \return <tt>(*this)</tt>
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    BellmanFord &predMap(PredMap &map) {
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      if(_local_pred) {
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	delete _pred;
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	_local_pred=false;
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      }
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      _pred = &map;
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      return *this;
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    }
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    /// \brief Sets the map that stores the distances of the nodes.
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    ///
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    /// Sets the map that stores the distances of the nodes calculated
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    /// by the algorithm.
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    /// If you don't use this function before calling \ref run()
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    /// or \ref init(), an instance will be allocated automatically.
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    /// The destructor deallocates this automatically allocated map,
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    /// of course.
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    /// \return <tt>(*this)</tt>
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    BellmanFord &distMap(DistMap &map) {
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      if(_local_dist) {
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	delete _dist;
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	_local_dist=false;
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      }
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      _dist = &map;
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      return *this;
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    }
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    /// \name Execution Control
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    /// The simplest way to execute the Bellman-Ford algorithm is to use
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    /// one of the member functions called \ref run().\n
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    /// If you need better control on the execution, you have to call
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    /// \ref init() first, then you can add several source nodes
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    /// with \ref addSource(). Finally the actual path computation can be
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    /// performed with \ref start(), \ref checkedStart() or
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    /// \ref limitedStart().
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    ///@{
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    /// \brief Initializes the internal data structures.
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    /// 
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    /// Initializes the internal data structures. The optional parameter
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    /// is the initial distance of each node.
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    void init(const Value value = OperationTraits::infinity()) {
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      create_maps();
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      for (NodeIt it(*_gr); it != INVALID; ++it) {
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   397
	_pred->set(it, INVALID);
kpeter@696
   398
	_dist->set(it, value);
kpeter@696
   399
      }
kpeter@696
   400
      _process.clear();
kpeter@696
   401
      if (OperationTraits::less(value, OperationTraits::infinity())) {
kpeter@697
   402
	for (NodeIt it(*_gr); it != INVALID; ++it) {
kpeter@696
   403
	  _process.push_back(it);
kpeter@696
   404
	  _mask->set(it, true);
kpeter@696
   405
	}
kpeter@696
   406
      }
kpeter@696
   407
    }
kpeter@696
   408
    
kpeter@696
   409
    /// \brief Adds a new source node.
kpeter@696
   410
    ///
kpeter@697
   411
    /// This function adds a new source node. The optional second parameter
kpeter@697
   412
    /// is the initial distance of the node.
kpeter@696
   413
    void addSource(Node source, Value dst = OperationTraits::zero()) {
kpeter@696
   414
      _dist->set(source, dst);
kpeter@696
   415
      if (!(*_mask)[source]) {
kpeter@696
   416
	_process.push_back(source);
kpeter@696
   417
	_mask->set(source, true);
kpeter@696
   418
      }
kpeter@696
   419
    }
kpeter@696
   420
kpeter@696
   421
    /// \brief Executes one round from the Bellman-Ford algorithm.
kpeter@696
   422
    ///
kpeter@696
   423
    /// If the algoritm calculated the distances in the previous round
kpeter@697
   424
    /// exactly for the paths of at most \c k arcs, then this function
kpeter@697
   425
    /// will calculate the distances exactly for the paths of at most
kpeter@697
   426
    /// <tt>k+1</tt> arcs. Performing \c k iterations using this function
kpeter@697
   427
    /// calculates the shortest path distances exactly for the paths
kpeter@697
   428
    /// consisting of at most \c k arcs.
kpeter@696
   429
    ///
kpeter@696
   430
    /// \warning The paths with limited arc number cannot be retrieved
kpeter@697
   431
    /// easily with \ref path() or \ref predArc() functions. If you also
kpeter@697
   432
    /// need the shortest paths and not only the distances, you should
kpeter@697
   433
    /// store the \ref predMap() "predecessor map" after each iteration
kpeter@697
   434
    /// and build the path manually.
kpeter@696
   435
    ///
kpeter@696
   436
    /// \return \c true when the algorithm have not found more shorter
kpeter@696
   437
    /// paths.
kpeter@697
   438
    ///
kpeter@697
   439
    /// \see ActiveIt
kpeter@696
   440
    bool processNextRound() {
kpeter@696
   441
      for (int i = 0; i < int(_process.size()); ++i) {
kpeter@696
   442
	_mask->set(_process[i], false);
kpeter@696
   443
      }
kpeter@696
   444
      std::vector<Node> nextProcess;
kpeter@696
   445
      std::vector<Value> values(_process.size());
kpeter@696
   446
      for (int i = 0; i < int(_process.size()); ++i) {
kpeter@696
   447
	values[i] = (*_dist)[_process[i]];
kpeter@696
   448
      }
kpeter@696
   449
      for (int i = 0; i < int(_process.size()); ++i) {
kpeter@697
   450
	for (OutArcIt it(*_gr, _process[i]); it != INVALID; ++it) {
kpeter@697
   451
	  Node target = _gr->target(it);
kpeter@697
   452
	  Value relaxed = OperationTraits::plus(values[i], (*_length)[it]);
kpeter@696
   453
	  if (OperationTraits::less(relaxed, (*_dist)[target])) {
kpeter@696
   454
	    _pred->set(target, it);
kpeter@696
   455
	    _dist->set(target, relaxed);
kpeter@696
   456
	    if (!(*_mask)[target]) {
kpeter@696
   457
	      _mask->set(target, true);
kpeter@696
   458
	      nextProcess.push_back(target);
kpeter@696
   459
	    }
kpeter@696
   460
	  }	  
kpeter@696
   461
	}
kpeter@696
   462
      }
kpeter@696
   463
      _process.swap(nextProcess);
kpeter@696
   464
      return _process.empty();
kpeter@696
   465
    }
kpeter@696
   466
kpeter@696
   467
    /// \brief Executes one weak round from the Bellman-Ford algorithm.
kpeter@696
   468
    ///
kpeter@697
   469
    /// If the algorithm calculated the distances in the previous round
kpeter@697
   470
    /// at least for the paths of at most \c k arcs, then this function
kpeter@697
   471
    /// will calculate the distances at least for the paths of at most
kpeter@697
   472
    /// <tt>k+1</tt> arcs.
kpeter@697
   473
    /// This function does not make it possible to calculate the shortest
kpeter@697
   474
    /// path distances exactly for paths consisting of at most \c k arcs,
kpeter@697
   475
    /// this is why it is called weak round.
kpeter@697
   476
    ///
kpeter@697
   477
    /// \return \c true when the algorithm have not found more shorter
kpeter@697
   478
    /// paths.
kpeter@697
   479
    ///
kpeter@697
   480
    /// \see ActiveIt
kpeter@696
   481
    bool processNextWeakRound() {
kpeter@696
   482
      for (int i = 0; i < int(_process.size()); ++i) {
kpeter@696
   483
	_mask->set(_process[i], false);
kpeter@696
   484
      }
kpeter@696
   485
      std::vector<Node> nextProcess;
kpeter@696
   486
      for (int i = 0; i < int(_process.size()); ++i) {
kpeter@697
   487
	for (OutArcIt it(*_gr, _process[i]); it != INVALID; ++it) {
kpeter@697
   488
	  Node target = _gr->target(it);
kpeter@696
   489
	  Value relaxed = 
kpeter@697
   490
	    OperationTraits::plus((*_dist)[_process[i]], (*_length)[it]);
kpeter@696
   491
	  if (OperationTraits::less(relaxed, (*_dist)[target])) {
kpeter@696
   492
	    _pred->set(target, it);
kpeter@696
   493
	    _dist->set(target, relaxed);
kpeter@696
   494
	    if (!(*_mask)[target]) {
kpeter@696
   495
	      _mask->set(target, true);
kpeter@696
   496
	      nextProcess.push_back(target);
kpeter@696
   497
	    }
kpeter@696
   498
	  }	  
kpeter@696
   499
	}
kpeter@696
   500
      }
kpeter@696
   501
      _process.swap(nextProcess);
kpeter@696
   502
      return _process.empty();
kpeter@696
   503
    }
kpeter@696
   504
kpeter@696
   505
    /// \brief Executes the algorithm.
kpeter@696
   506
    ///
kpeter@697
   507
    /// Executes the algorithm.
kpeter@696
   508
    ///
kpeter@697
   509
    /// This method runs the Bellman-Ford algorithm from the root node(s)
kpeter@697
   510
    /// in order to compute the shortest path to each node.
kpeter@697
   511
    ///
kpeter@697
   512
    /// The algorithm computes
kpeter@697
   513
    /// - the shortest path tree (forest),
kpeter@697
   514
    /// - the distance of each node from the root(s).
kpeter@697
   515
    ///
kpeter@697
   516
    /// \pre init() must be called and at least one root node should be
kpeter@697
   517
    /// added with addSource() before using this function.
kpeter@696
   518
    void start() {
kpeter@697
   519
      int num = countNodes(*_gr) - 1;
kpeter@696
   520
      for (int i = 0; i < num; ++i) {
kpeter@696
   521
	if (processNextWeakRound()) break;
kpeter@696
   522
      }
kpeter@696
   523
    }
kpeter@696
   524
kpeter@696
   525
    /// \brief Executes the algorithm and checks the negative cycles.
kpeter@696
   526
    ///
kpeter@697
   527
    /// Executes the algorithm and checks the negative cycles.
kpeter@696
   528
    ///
kpeter@697
   529
    /// This method runs the Bellman-Ford algorithm from the root node(s)
kpeter@697
   530
    /// in order to compute the shortest path to each node and also checks
kpeter@697
   531
    /// if the digraph contains cycles with negative total length.
kpeter@697
   532
    ///
kpeter@697
   533
    /// The algorithm computes 
kpeter@697
   534
    /// - the shortest path tree (forest),
kpeter@697
   535
    /// - the distance of each node from the root(s).
kpeter@696
   536
    /// 
kpeter@696
   537
    /// \return \c false if there is a negative cycle in the digraph.
kpeter@697
   538
    ///
kpeter@697
   539
    /// \pre init() must be called and at least one root node should be
kpeter@697
   540
    /// added with addSource() before using this function. 
kpeter@696
   541
    bool checkedStart() {
kpeter@697
   542
      int num = countNodes(*_gr);
kpeter@696
   543
      for (int i = 0; i < num; ++i) {
kpeter@696
   544
	if (processNextWeakRound()) return true;
kpeter@696
   545
      }
kpeter@696
   546
      return _process.empty();
kpeter@696
   547
    }
kpeter@696
   548
kpeter@697
   549
    /// \brief Executes the algorithm with arc number limit.
kpeter@696
   550
    ///
kpeter@697
   551
    /// Executes the algorithm with arc number limit.
kpeter@696
   552
    ///
kpeter@697
   553
    /// This method runs the Bellman-Ford algorithm from the root node(s)
kpeter@697
   554
    /// in order to compute the shortest path distance for each node
kpeter@697
   555
    /// using only the paths consisting of at most \c num arcs.
kpeter@697
   556
    ///
kpeter@697
   557
    /// The algorithm computes
kpeter@697
   558
    /// - the limited distance of each node from the root(s),
kpeter@697
   559
    /// - the predecessor arc for each node.
kpeter@696
   560
    ///
kpeter@696
   561
    /// \warning The paths with limited arc number cannot be retrieved
kpeter@697
   562
    /// easily with \ref path() or \ref predArc() functions. If you also
kpeter@697
   563
    /// need the shortest paths and not only the distances, you should
kpeter@697
   564
    /// store the \ref predMap() "predecessor map" after each iteration
kpeter@697
   565
    /// and build the path manually.
kpeter@696
   566
    ///
kpeter@697
   567
    /// \pre init() must be called and at least one root node should be
kpeter@697
   568
    /// added with addSource() before using this function. 
kpeter@696
   569
    void limitedStart(int num) {
kpeter@696
   570
      for (int i = 0; i < num; ++i) {
kpeter@696
   571
	if (processNextRound()) break;
kpeter@696
   572
      }
kpeter@696
   573
    }
kpeter@696
   574
    
kpeter@697
   575
    /// \brief Runs the algorithm from the given root node.
kpeter@696
   576
    ///    
kpeter@697
   577
    /// This method runs the Bellman-Ford algorithm from the given root
kpeter@697
   578
    /// node \c s in order to compute the shortest path to each node.
kpeter@696
   579
    ///
kpeter@697
   580
    /// The algorithm computes
kpeter@697
   581
    /// - the shortest path tree (forest),
kpeter@697
   582
    /// - the distance of each node from the root(s).
kpeter@697
   583
    ///
kpeter@697
   584
    /// \note bf.run(s) is just a shortcut of the following code.
kpeter@697
   585
    /// \code
kpeter@697
   586
    ///   bf.init();
kpeter@697
   587
    ///   bf.addSource(s);
kpeter@697
   588
    ///   bf.start();
kpeter@697
   589
    /// \endcode
kpeter@696
   590
    void run(Node s) {
kpeter@696
   591
      init();
kpeter@696
   592
      addSource(s);
kpeter@696
   593
      start();
kpeter@696
   594
    }
kpeter@696
   595
    
kpeter@697
   596
    /// \brief Runs the algorithm from the given root node with arc
kpeter@697
   597
    /// number limit.
kpeter@696
   598
    ///    
kpeter@697
   599
    /// This method runs the Bellman-Ford algorithm from the given root
kpeter@697
   600
    /// node \c s in order to compute the shortest path distance for each
kpeter@697
   601
    /// node using only the paths consisting of at most \c num arcs.
kpeter@696
   602
    ///
kpeter@697
   603
    /// The algorithm computes
kpeter@697
   604
    /// - the limited distance of each node from the root(s),
kpeter@697
   605
    /// - the predecessor arc for each node.
kpeter@697
   606
    ///
kpeter@697
   607
    /// \warning The paths with limited arc number cannot be retrieved
kpeter@697
   608
    /// easily with \ref path() or \ref predArc() functions. If you also
kpeter@697
   609
    /// need the shortest paths and not only the distances, you should
kpeter@697
   610
    /// store the \ref predMap() "predecessor map" after each iteration
kpeter@697
   611
    /// and build the path manually.
kpeter@697
   612
    ///
kpeter@697
   613
    /// \note bf.run(s, num) is just a shortcut of the following code.
kpeter@697
   614
    /// \code
kpeter@697
   615
    ///   bf.init();
kpeter@697
   616
    ///   bf.addSource(s);
kpeter@697
   617
    ///   bf.limitedStart(num);
kpeter@697
   618
    /// \endcode
kpeter@696
   619
    void run(Node s, int num) {
kpeter@696
   620
      init();
kpeter@696
   621
      addSource(s);
kpeter@696
   622
      limitedStart(num);
kpeter@696
   623
    }
kpeter@696
   624
    
kpeter@696
   625
    ///@}
kpeter@696
   626
kpeter@697
   627
    /// \brief LEMON iterator for getting the active nodes.
kpeter@696
   628
    ///
kpeter@697
   629
    /// This class provides a common style LEMON iterator that traverses
kpeter@697
   630
    /// the active nodes of the Bellman-Ford algorithm after the last
kpeter@697
   631
    /// phase. These nodes should be checked in the next phase to
kpeter@697
   632
    /// find augmenting arcs outgoing from them.
kpeter@696
   633
    class ActiveIt {
kpeter@696
   634
    public:
kpeter@696
   635
kpeter@696
   636
      /// \brief Constructor.
kpeter@696
   637
      ///
kpeter@697
   638
      /// Constructor for getting the active nodes of the given BellmanFord
kpeter@697
   639
      /// instance. 
kpeter@696
   640
      ActiveIt(const BellmanFord& algorithm) : _algorithm(&algorithm)
kpeter@696
   641
      {
kpeter@696
   642
        _index = _algorithm->_process.size() - 1;
kpeter@696
   643
      }
kpeter@696
   644
kpeter@696
   645
      /// \brief Invalid constructor.
kpeter@696
   646
      ///
kpeter@696
   647
      /// Invalid constructor.
kpeter@696
   648
      ActiveIt(Invalid) : _algorithm(0), _index(-1) {}
kpeter@696
   649
kpeter@697
   650
      /// \brief Conversion to \c Node.
kpeter@696
   651
      ///
kpeter@697
   652
      /// Conversion to \c Node.
kpeter@696
   653
      operator Node() const { 
kpeter@696
   654
        return _index >= 0 ? _algorithm->_process[_index] : INVALID;
kpeter@696
   655
      }
kpeter@696
   656
kpeter@696
   657
      /// \brief Increment operator.
kpeter@696
   658
      ///
kpeter@696
   659
      /// Increment operator.
kpeter@696
   660
      ActiveIt& operator++() {
kpeter@696
   661
        --_index;
kpeter@696
   662
        return *this; 
kpeter@696
   663
      }
kpeter@696
   664
kpeter@696
   665
      bool operator==(const ActiveIt& it) const { 
kpeter@696
   666
        return static_cast<Node>(*this) == static_cast<Node>(it); 
kpeter@696
   667
      }
kpeter@696
   668
      bool operator!=(const ActiveIt& it) const { 
kpeter@696
   669
        return static_cast<Node>(*this) != static_cast<Node>(it); 
kpeter@696
   670
      }
kpeter@696
   671
      bool operator<(const ActiveIt& it) const { 
kpeter@696
   672
        return static_cast<Node>(*this) < static_cast<Node>(it); 
kpeter@696
   673
      }
kpeter@696
   674
      
kpeter@696
   675
    private:
kpeter@696
   676
      const BellmanFord* _algorithm;
kpeter@696
   677
      int _index;
kpeter@696
   678
    };
kpeter@697
   679
    
kpeter@697
   680
    /// \name Query Functions
kpeter@697
   681
    /// The result of the Bellman-Ford algorithm can be obtained using these
kpeter@697
   682
    /// functions.\n
kpeter@697
   683
    /// Either \ref run() or \ref init() should be called before using them.
kpeter@697
   684
    
kpeter@697
   685
    ///@{
kpeter@696
   686
kpeter@697
   687
    /// \brief The shortest path to the given node.
kpeter@697
   688
    ///    
kpeter@697
   689
    /// Gives back the shortest path to the given node from the root(s).
kpeter@697
   690
    ///
kpeter@697
   691
    /// \warning \c t should be reached from the root(s).
kpeter@697
   692
    ///
kpeter@697
   693
    /// \pre Either \ref run() or \ref init() must be called before
kpeter@697
   694
    /// using this function.
kpeter@697
   695
    Path path(Node t) const
kpeter@697
   696
    {
kpeter@697
   697
      return Path(*_gr, *_pred, t);
kpeter@697
   698
    }
kpeter@697
   699
	  
kpeter@697
   700
    /// \brief The distance of the given node from the root(s).
kpeter@697
   701
    ///
kpeter@697
   702
    /// Returns the distance of the given node from the root(s).
kpeter@697
   703
    ///
kpeter@697
   704
    /// \warning If node \c v is not reached from the root(s), then
kpeter@697
   705
    /// the return value of this function is undefined.
kpeter@697
   706
    ///
kpeter@697
   707
    /// \pre Either \ref run() or \ref init() must be called before
kpeter@697
   708
    /// using this function.
kpeter@697
   709
    Value dist(Node v) const { return (*_dist)[v]; }
kpeter@696
   710
kpeter@697
   711
    /// \brief Returns the 'previous arc' of the shortest path tree for
kpeter@697
   712
    /// the given node.
kpeter@697
   713
    ///
kpeter@697
   714
    /// This function returns the 'previous arc' of the shortest path
kpeter@697
   715
    /// tree for node \c v, i.e. it returns the last arc of a
kpeter@697
   716
    /// shortest path from a root to \c v. It is \c INVALID if \c v
kpeter@697
   717
    /// is not reached from the root(s) or if \c v is a root.
kpeter@697
   718
    ///
kpeter@697
   719
    /// The shortest path tree used here is equal to the shortest path
kpeter@697
   720
    /// tree used in \ref predNode() and \predMap().
kpeter@697
   721
    ///
kpeter@697
   722
    /// \pre Either \ref run() or \ref init() must be called before
kpeter@697
   723
    /// using this function.
kpeter@697
   724
    Arc predArc(Node v) const { return (*_pred)[v]; }
kpeter@697
   725
kpeter@697
   726
    /// \brief Returns the 'previous node' of the shortest path tree for
kpeter@697
   727
    /// the given node.
kpeter@697
   728
    ///
kpeter@697
   729
    /// This function returns the 'previous node' of the shortest path
kpeter@697
   730
    /// tree for node \c v, i.e. it returns the last but one node of
kpeter@697
   731
    /// a shortest path from a root to \c v. It is \c INVALID if \c v
kpeter@697
   732
    /// is not reached from the root(s) or if \c v is a root.
kpeter@697
   733
    ///
kpeter@697
   734
    /// The shortest path tree used here is equal to the shortest path
kpeter@697
   735
    /// tree used in \ref predArc() and \predMap().
kpeter@697
   736
    ///
kpeter@697
   737
    /// \pre Either \ref run() or \ref init() must be called before
kpeter@697
   738
    /// using this function.
kpeter@697
   739
    Node predNode(Node v) const { 
kpeter@697
   740
      return (*_pred)[v] == INVALID ? INVALID : _gr->source((*_pred)[v]); 
kpeter@697
   741
    }
kpeter@697
   742
    
kpeter@697
   743
    /// \brief Returns a const reference to the node map that stores the
kpeter@697
   744
    /// distances of the nodes.
kpeter@697
   745
    ///
kpeter@697
   746
    /// Returns a const reference to the node map that stores the distances
kpeter@697
   747
    /// of the nodes calculated by the algorithm.
kpeter@697
   748
    ///
kpeter@697
   749
    /// \pre Either \ref run() or \ref init() must be called before
kpeter@697
   750
    /// using this function.
kpeter@697
   751
    const DistMap &distMap() const { return *_dist;}
kpeter@697
   752
 
kpeter@697
   753
    /// \brief Returns a const reference to the node map that stores the
kpeter@697
   754
    /// predecessor arcs.
kpeter@697
   755
    ///
kpeter@697
   756
    /// Returns a const reference to the node map that stores the predecessor
kpeter@697
   757
    /// arcs, which form the shortest path tree (forest).
kpeter@697
   758
    ///
kpeter@697
   759
    /// \pre Either \ref run() or \ref init() must be called before
kpeter@697
   760
    /// using this function.
kpeter@697
   761
    const PredMap &predMap() const { return *_pred; }
kpeter@697
   762
 
kpeter@697
   763
    /// \brief Checks if a node is reached from the root(s).
kpeter@697
   764
    ///
kpeter@697
   765
    /// Returns \c true if \c v is reached from the root(s).
kpeter@697
   766
    ///
kpeter@697
   767
    /// \pre Either \ref run() or \ref init() must be called before
kpeter@697
   768
    /// using this function.
kpeter@697
   769
    bool reached(Node v) const {
kpeter@697
   770
      return (*_dist)[v] != OperationTraits::infinity();
kpeter@696
   771
    }
kpeter@696
   772
kpeter@699
   773
    /// \brief Gives back a negative cycle.
kpeter@699
   774
    ///    
kpeter@699
   775
    /// This function gives back a directed cycle with negative total
kpeter@699
   776
    /// length if the algorithm has already found one.
kpeter@699
   777
    /// Otherwise it gives back an empty path.
kpeter@699
   778
    lemon::Path<Digraph> negativeCycle() {
kpeter@699
   779
      typename Digraph::template NodeMap<int> state(*_gr, -1);
kpeter@699
   780
      lemon::Path<Digraph> cycle;
kpeter@699
   781
      for (int i = 0; i < int(_process.size()); ++i) {
kpeter@699
   782
        if (state[_process[i]] != -1) continue;
kpeter@699
   783
        for (Node v = _process[i]; (*_pred)[v] != INVALID;
kpeter@699
   784
             v = _gr->source((*_pred)[v])) {
kpeter@699
   785
          if (state[v] == i) {
kpeter@699
   786
            cycle.addFront((*_pred)[v]);
kpeter@699
   787
            for (Node u = _gr->source((*_pred)[v]); u != v;
kpeter@699
   788
                 u = _gr->source((*_pred)[u])) {
kpeter@699
   789
              cycle.addFront((*_pred)[u]);
kpeter@699
   790
            }
kpeter@699
   791
            return cycle;
kpeter@699
   792
          }
kpeter@699
   793
          else if (state[v] >= 0) {
kpeter@699
   794
            break;
kpeter@699
   795
          }
kpeter@699
   796
          state[v] = i;
kpeter@699
   797
        }
kpeter@699
   798
      }
kpeter@699
   799
      return cycle;
kpeter@699
   800
    }
kpeter@696
   801
    
kpeter@696
   802
    ///@}
kpeter@696
   803
  };
kpeter@696
   804
 
kpeter@697
   805
  /// \brief Default traits class of bellmanFord() function.
kpeter@696
   806
  ///
kpeter@697
   807
  /// Default traits class of bellmanFord() function.
kpeter@697
   808
  /// \tparam GR The type of the digraph.
kpeter@697
   809
  /// \tparam LEN The type of the length map.
kpeter@697
   810
  template <typename GR, typename LEN>
kpeter@696
   811
  struct BellmanFordWizardDefaultTraits {
kpeter@697
   812
    /// The type of the digraph the algorithm runs on. 
kpeter@697
   813
    typedef GR Digraph;
kpeter@696
   814
kpeter@696
   815
    /// \brief The type of the map that stores the arc lengths.
kpeter@696
   816
    ///
kpeter@696
   817
    /// The type of the map that stores the arc lengths.
kpeter@696
   818
    /// It must meet the \ref concepts::ReadMap "ReadMap" concept.
kpeter@697
   819
    typedef LEN LengthMap;
kpeter@696
   820
kpeter@697
   821
    /// The type of the arc lengths.
kpeter@697
   822
    typedef typename LEN::Value Value;
kpeter@696
   823
kpeter@696
   824
    /// \brief Operation traits for Bellman-Ford algorithm.
kpeter@696
   825
    ///
kpeter@697
   826
    /// It defines the used operations and the infinity value for the
kpeter@697
   827
    /// given \c Value type.
kpeter@696
   828
    /// \see BellmanFordDefaultOperationTraits
kpeter@696
   829
    typedef BellmanFordDefaultOperationTraits<Value> OperationTraits;
kpeter@696
   830
kpeter@696
   831
    /// \brief The type of the map that stores the last
kpeter@696
   832
    /// arcs of the shortest paths.
kpeter@696
   833
    /// 
kpeter@697
   834
    /// The type of the map that stores the last arcs of the shortest paths.
kpeter@697
   835
    /// It must conform to the \ref concepts::WriteMap "WriteMap" concept.
kpeter@697
   836
    typedef typename GR::template NodeMap<typename GR::Arc> PredMap;
kpeter@696
   837
kpeter@697
   838
    /// \brief Instantiates a \c PredMap.
kpeter@696
   839
    /// 
kpeter@697
   840
    /// This function instantiates a \ref PredMap.
kpeter@697
   841
    /// \param g is the digraph to which we would like to define the
kpeter@697
   842
    /// \ref PredMap.
kpeter@697
   843
    static PredMap *createPredMap(const GR &g) {
kpeter@697
   844
      return new PredMap(g);
kpeter@696
   845
    }
kpeter@697
   846
kpeter@697
   847
    /// \brief The type of the map that stores the distances of the nodes.
kpeter@696
   848
    ///
kpeter@697
   849
    /// The type of the map that stores the distances of the nodes.
kpeter@697
   850
    /// It must conform to the \ref concepts::WriteMap "WriteMap" concept.
kpeter@697
   851
    typedef typename GR::template NodeMap<Value> DistMap;
kpeter@697
   852
kpeter@697
   853
    /// \brief Instantiates a \c DistMap.
kpeter@696
   854
    ///
kpeter@696
   855
    /// This function instantiates a \ref DistMap. 
kpeter@697
   856
    /// \param g is the digraph to which we would like to define the
kpeter@697
   857
    /// \ref DistMap.
kpeter@697
   858
    static DistMap *createDistMap(const GR &g) {
kpeter@697
   859
      return new DistMap(g);
kpeter@696
   860
    }
kpeter@697
   861
kpeter@697
   862
    ///The type of the shortest paths.
kpeter@697
   863
kpeter@697
   864
    ///The type of the shortest paths.
kpeter@697
   865
    ///It must meet the \ref concepts::Path "Path" concept.
kpeter@697
   866
    typedef lemon::Path<Digraph> Path;
kpeter@696
   867
  };
kpeter@696
   868
  
kpeter@697
   869
  /// \brief Default traits class used by BellmanFordWizard.
kpeter@696
   870
  ///
kpeter@697
   871
  /// Default traits class used by BellmanFordWizard.
kpeter@697
   872
  /// \tparam GR The type of the digraph.
kpeter@697
   873
  /// \tparam LEN The type of the length map.
kpeter@697
   874
  template <typename GR, typename LEN>
kpeter@696
   875
  class BellmanFordWizardBase 
kpeter@697
   876
    : public BellmanFordWizardDefaultTraits<GR, LEN> {
kpeter@696
   877
kpeter@697
   878
    typedef BellmanFordWizardDefaultTraits<GR, LEN> Base;
kpeter@696
   879
  protected:
kpeter@697
   880
    // Type of the nodes in the digraph.
kpeter@696
   881
    typedef typename Base::Digraph::Node Node;
kpeter@696
   882
kpeter@697
   883
    // Pointer to the underlying digraph.
kpeter@696
   884
    void *_graph;
kpeter@697
   885
    // Pointer to the length map
kpeter@696
   886
    void *_length;
kpeter@697
   887
    // Pointer to the map of predecessors arcs.
kpeter@696
   888
    void *_pred;
kpeter@697
   889
    // Pointer to the map of distances.
kpeter@696
   890
    void *_dist;
kpeter@697
   891
    //Pointer to the shortest path to the target node.
kpeter@697
   892
    void *_path;
kpeter@697
   893
    //Pointer to the distance of the target node.
kpeter@697
   894
    void *_di;
kpeter@696
   895
kpeter@696
   896
    public:
kpeter@696
   897
    /// Constructor.
kpeter@696
   898
    
kpeter@697
   899
    /// This constructor does not require parameters, it initiates
kpeter@697
   900
    /// all of the attributes to default values \c 0.
kpeter@697
   901
    BellmanFordWizardBase() :
kpeter@697
   902
      _graph(0), _length(0), _pred(0), _dist(0), _path(0), _di(0) {}
kpeter@696
   903
kpeter@696
   904
    /// Constructor.
kpeter@696
   905
    
kpeter@697
   906
    /// This constructor requires two parameters,
kpeter@697
   907
    /// others are initiated to \c 0.
kpeter@697
   908
    /// \param gr The digraph the algorithm runs on.
kpeter@697
   909
    /// \param len The length map.
kpeter@697
   910
    BellmanFordWizardBase(const GR& gr, 
kpeter@697
   911
			  const LEN& len) :
kpeter@697
   912
      _graph(reinterpret_cast<void*>(const_cast<GR*>(&gr))), 
kpeter@697
   913
      _length(reinterpret_cast<void*>(const_cast<LEN*>(&len))), 
kpeter@697
   914
      _pred(0), _dist(0), _path(0), _di(0) {}
kpeter@696
   915
kpeter@696
   916
  };
kpeter@696
   917
  
kpeter@697
   918
  /// \brief Auxiliary class for the function-type interface of the
kpeter@697
   919
  /// \ref BellmanFord "Bellman-Ford" algorithm.
kpeter@697
   920
  ///
kpeter@697
   921
  /// This auxiliary class is created to implement the
kpeter@697
   922
  /// \ref bellmanFord() "function-type interface" of the
kpeter@697
   923
  /// \ref BellmanFord "Bellman-Ford" algorithm.
kpeter@697
   924
  /// It does not have own \ref run() method, it uses the
kpeter@697
   925
  /// functions and features of the plain \ref BellmanFord.
kpeter@697
   926
  ///
kpeter@697
   927
  /// This class should only be used through the \ref bellmanFord()
kpeter@697
   928
  /// function, which makes it easier to use the algorithm.
kpeter@697
   929
  template<class TR>
kpeter@697
   930
  class BellmanFordWizard : public TR {
kpeter@697
   931
    typedef TR Base;
kpeter@696
   932
kpeter@697
   933
    typedef typename TR::Digraph Digraph;
kpeter@696
   934
kpeter@696
   935
    typedef typename Digraph::Node Node;
kpeter@696
   936
    typedef typename Digraph::NodeIt NodeIt;
kpeter@696
   937
    typedef typename Digraph::Arc Arc;
kpeter@696
   938
    typedef typename Digraph::OutArcIt ArcIt;
kpeter@696
   939
    
kpeter@697
   940
    typedef typename TR::LengthMap LengthMap;
kpeter@696
   941
    typedef typename LengthMap::Value Value;
kpeter@697
   942
    typedef typename TR::PredMap PredMap;
kpeter@697
   943
    typedef typename TR::DistMap DistMap;
kpeter@697
   944
    typedef typename TR::Path Path;
kpeter@696
   945
kpeter@696
   946
  public:
kpeter@696
   947
    /// Constructor.
kpeter@697
   948
    BellmanFordWizard() : TR() {}
kpeter@696
   949
kpeter@696
   950
    /// \brief Constructor that requires parameters.
kpeter@696
   951
    ///
kpeter@696
   952
    /// Constructor that requires parameters.
kpeter@696
   953
    /// These parameters will be the default values for the traits class.
kpeter@697
   954
    /// \param gr The digraph the algorithm runs on.
kpeter@697
   955
    /// \param len The length map.
kpeter@697
   956
    BellmanFordWizard(const Digraph& gr, const LengthMap& len) 
kpeter@697
   957
      : TR(gr, len) {}
kpeter@696
   958
kpeter@696
   959
    /// \brief Copy constructor
kpeter@697
   960
    BellmanFordWizard(const TR &b) : TR(b) {}
kpeter@696
   961
kpeter@696
   962
    ~BellmanFordWizard() {}
kpeter@696
   963
kpeter@697
   964
    /// \brief Runs the Bellman-Ford algorithm from the given source node.
kpeter@696
   965
    ///    
kpeter@697
   966
    /// This method runs the Bellman-Ford algorithm from the given source
kpeter@697
   967
    /// node in order to compute the shortest path to each node.
kpeter@697
   968
    void run(Node s) {
kpeter@697
   969
      BellmanFord<Digraph,LengthMap,TR> 
kpeter@696
   970
	bf(*reinterpret_cast<const Digraph*>(Base::_graph), 
kpeter@696
   971
           *reinterpret_cast<const LengthMap*>(Base::_length));
kpeter@696
   972
      if (Base::_pred) bf.predMap(*reinterpret_cast<PredMap*>(Base::_pred));
kpeter@696
   973
      if (Base::_dist) bf.distMap(*reinterpret_cast<DistMap*>(Base::_dist));
kpeter@697
   974
      bf.run(s);
kpeter@696
   975
    }
kpeter@696
   976
kpeter@697
   977
    /// \brief Runs the Bellman-Ford algorithm to find the shortest path
kpeter@697
   978
    /// between \c s and \c t.
kpeter@696
   979
    ///
kpeter@697
   980
    /// This method runs the Bellman-Ford algorithm from node \c s
kpeter@697
   981
    /// in order to compute the shortest path to node \c t.
kpeter@697
   982
    /// Actually, it computes the shortest path to each node, but using
kpeter@697
   983
    /// this function you can retrieve the distance and the shortest path
kpeter@697
   984
    /// for a single target node easier.
kpeter@697
   985
    ///
kpeter@697
   986
    /// \return \c true if \c t is reachable form \c s.
kpeter@697
   987
    bool run(Node s, Node t) {
kpeter@697
   988
      BellmanFord<Digraph,LengthMap,TR>
kpeter@697
   989
        bf(*reinterpret_cast<const Digraph*>(Base::_graph),
kpeter@697
   990
           *reinterpret_cast<const LengthMap*>(Base::_length));
kpeter@697
   991
      if (Base::_pred) bf.predMap(*reinterpret_cast<PredMap*>(Base::_pred));
kpeter@697
   992
      if (Base::_dist) bf.distMap(*reinterpret_cast<DistMap*>(Base::_dist));
kpeter@697
   993
      bf.run(s);
kpeter@697
   994
      if (Base::_path) *reinterpret_cast<Path*>(Base::_path) = bf.path(t);
kpeter@697
   995
      if (Base::_di) *reinterpret_cast<Value*>(Base::_di) = bf.dist(t);
kpeter@697
   996
      return bf.reached(t);
kpeter@696
   997
    }
kpeter@696
   998
kpeter@696
   999
    template<class T>
kpeter@697
  1000
    struct SetPredMapBase : public Base {
kpeter@696
  1001
      typedef T PredMap;
kpeter@696
  1002
      static PredMap *createPredMap(const Digraph &) { return 0; };
kpeter@697
  1003
      SetPredMapBase(const TR &b) : TR(b) {}
kpeter@696
  1004
    };
kpeter@696
  1005
    
kpeter@697
  1006
    /// \brief \ref named-templ-param "Named parameter" for setting
kpeter@697
  1007
    /// the predecessor map.
kpeter@696
  1008
    ///
kpeter@697
  1009
    /// \ref named-templ-param "Named parameter" for setting
kpeter@697
  1010
    /// the map that stores the predecessor arcs of the nodes.
kpeter@696
  1011
    template<class T>
kpeter@697
  1012
    BellmanFordWizard<SetPredMapBase<T> > predMap(const T &t) {
kpeter@696
  1013
      Base::_pred=reinterpret_cast<void*>(const_cast<T*>(&t));
kpeter@697
  1014
      return BellmanFordWizard<SetPredMapBase<T> >(*this);
kpeter@696
  1015
    }
kpeter@696
  1016
    
kpeter@696
  1017
    template<class T>
kpeter@697
  1018
    struct SetDistMapBase : public Base {
kpeter@696
  1019
      typedef T DistMap;
kpeter@696
  1020
      static DistMap *createDistMap(const Digraph &) { return 0; };
kpeter@697
  1021
      SetDistMapBase(const TR &b) : TR(b) {}
kpeter@696
  1022
    };
kpeter@696
  1023
    
kpeter@697
  1024
    /// \brief \ref named-templ-param "Named parameter" for setting
kpeter@697
  1025
    /// the distance map.
kpeter@696
  1026
    ///
kpeter@697
  1027
    /// \ref named-templ-param "Named parameter" for setting
kpeter@697
  1028
    /// the map that stores the distances of the nodes calculated
kpeter@697
  1029
    /// by the algorithm.
kpeter@696
  1030
    template<class T>
kpeter@697
  1031
    BellmanFordWizard<SetDistMapBase<T> > distMap(const T &t) {
kpeter@696
  1032
      Base::_dist=reinterpret_cast<void*>(const_cast<T*>(&t));
kpeter@697
  1033
      return BellmanFordWizard<SetDistMapBase<T> >(*this);
kpeter@696
  1034
    }
kpeter@696
  1035
kpeter@696
  1036
    template<class T>
kpeter@697
  1037
    struct SetPathBase : public Base {
kpeter@697
  1038
      typedef T Path;
kpeter@697
  1039
      SetPathBase(const TR &b) : TR(b) {}
kpeter@696
  1040
    };
kpeter@697
  1041
kpeter@697
  1042
    /// \brief \ref named-func-param "Named parameter" for getting
kpeter@697
  1043
    /// the shortest path to the target node.
kpeter@696
  1044
    ///
kpeter@697
  1045
    /// \ref named-func-param "Named parameter" for getting
kpeter@697
  1046
    /// the shortest path to the target node.
kpeter@697
  1047
    template<class T>
kpeter@697
  1048
    BellmanFordWizard<SetPathBase<T> > path(const T &t)
kpeter@697
  1049
    {
kpeter@697
  1050
      Base::_path=reinterpret_cast<void*>(const_cast<T*>(&t));
kpeter@697
  1051
      return BellmanFordWizard<SetPathBase<T> >(*this);
kpeter@697
  1052
    }
kpeter@697
  1053
kpeter@697
  1054
    /// \brief \ref named-func-param "Named parameter" for getting
kpeter@697
  1055
    /// the distance of the target node.
kpeter@696
  1056
    ///
kpeter@697
  1057
    /// \ref named-func-param "Named parameter" for getting
kpeter@697
  1058
    /// the distance of the target node.
kpeter@697
  1059
    BellmanFordWizard dist(const Value &d)
kpeter@697
  1060
    {
kpeter@697
  1061
      Base::_di=reinterpret_cast<void*>(const_cast<Value*>(&d));
kpeter@696
  1062
      return *this;
kpeter@696
  1063
    }
kpeter@696
  1064
    
kpeter@696
  1065
  };
kpeter@696
  1066
  
kpeter@697
  1067
  /// \brief Function type interface for the \ref BellmanFord "Bellman-Ford"
kpeter@697
  1068
  /// algorithm.
kpeter@696
  1069
  ///
kpeter@696
  1070
  /// \ingroup shortest_path
kpeter@697
  1071
  /// Function type interface for the \ref BellmanFord "Bellman-Ford"
kpeter@697
  1072
  /// algorithm.
kpeter@696
  1073
  ///
kpeter@696
  1074
  /// This function also has several \ref named-templ-func-param 
kpeter@696
  1075
  /// "named parameters", they are declared as the members of class 
kpeter@696
  1076
  /// \ref BellmanFordWizard.
kpeter@697
  1077
  /// The following examples show how to use these parameters.
kpeter@697
  1078
  /// \code
kpeter@697
  1079
  ///   // Compute shortest path from node s to each node
kpeter@697
  1080
  ///   bellmanFord(g,length).predMap(preds).distMap(dists).run(s);
kpeter@697
  1081
  ///
kpeter@697
  1082
  ///   // Compute shortest path from s to t
kpeter@697
  1083
  ///   bool reached = bellmanFord(g,length).path(p).dist(d).run(s,t);
kpeter@697
  1084
  /// \endcode
kpeter@696
  1085
  /// \warning Don't forget to put the \ref BellmanFordWizard::run() "run()"
kpeter@696
  1086
  /// to the end of the parameter list.
kpeter@696
  1087
  /// \sa BellmanFordWizard
kpeter@696
  1088
  /// \sa BellmanFord
kpeter@697
  1089
  template<typename GR, typename LEN>
kpeter@697
  1090
  BellmanFordWizard<BellmanFordWizardBase<GR,LEN> >
kpeter@697
  1091
  bellmanFord(const GR& digraph,
kpeter@697
  1092
	      const LEN& length)
kpeter@697
  1093
  {
kpeter@697
  1094
    return BellmanFordWizard<BellmanFordWizardBase<GR,LEN> >(digraph, length);
kpeter@696
  1095
  }
kpeter@696
  1096
kpeter@696
  1097
} //END OF NAMESPACE LEMON
kpeter@696
  1098
kpeter@696
  1099
#endif
kpeter@696
  1100