lemon/dfs.h
author Balazs Dezso <deba@inf.elte.hu>
Thu, 04 Mar 2010 15:20:59 +0100
changeset 951 41d7ac528c3a
parent 525 9605e051942f
child 760 4ac30454f1c1
child 763 f47b6c94577e
child 1009 c85f53572941
permissions -rw-r--r--
Uniforming primal scale to 2 (#314)
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/* -*- mode: C++; indent-tabs-mode: nil; -*-
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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) 2003-2009
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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_DFS_H
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#define LEMON_DFS_H
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///\ingroup search
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///\file
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///\brief DFS algorithm.
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#include <lemon/list_graph.h>
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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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namespace lemon {
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  ///Default traits class of Dfs class.
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  ///Default traits class of Dfs class.
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  ///\tparam GR Digraph type.
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  template<class GR>
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  struct DfsDefaultTraits
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  {
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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 predecessor
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    ///arcs of the %DFS paths.
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    ///
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    ///The type of the map that stores the predecessor
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    ///arcs of the %DFS paths.
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    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
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    typedef typename Digraph::template NodeMap<typename Digraph::Arc> PredMap;
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    ///Instantiates a \c PredMap.
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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 Digraph &g)
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    {
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      return new PredMap(g);
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    }
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    ///The type of the map that indicates which nodes are processed.
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    ///The type of the map that indicates which nodes are processed.
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    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
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    typedef NullMap<typename Digraph::Node,bool> ProcessedMap;
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    ///Instantiates a \c ProcessedMap.
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    ///This function instantiates a \ref ProcessedMap.
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    ///\param g is the digraph, to which
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    ///we would like to define the \ref ProcessedMap.
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#ifdef DOXYGEN
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    static ProcessedMap *createProcessedMap(const Digraph &g)
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#else
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    static ProcessedMap *createProcessedMap(const Digraph &)
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#endif
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    {
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      return new ProcessedMap();
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    }
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    ///The type of the map that indicates which nodes are reached.
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    ///The type of the map that indicates which nodes are reached.
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    ///It must meet the \ref concepts::ReadWriteMap "ReadWriteMap" concept.
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    typedef typename Digraph::template NodeMap<bool> ReachedMap;
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    ///Instantiates a \c ReachedMap.
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    ///This function instantiates a \ref ReachedMap.
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    ///\param g is the digraph, to which
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    ///we would like to define the \ref ReachedMap.
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    static ReachedMap *createReachedMap(const Digraph &g)
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    {
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      return new ReachedMap(g);
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    }
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    ///The type of the map that stores the distances of the nodes.
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    ///The type of the map that stores the distances of the nodes.
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    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
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    typedef typename Digraph::template NodeMap<int> DistMap;
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    ///Instantiates a \c DistMap.
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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 Digraph &g)
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    {
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      return new DistMap(g);
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    }
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  };
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  ///%DFS algorithm class.
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  ///\ingroup search
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  ///This class provides an efficient implementation of the %DFS algorithm.
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  ///
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  ///There is also a \ref dfs() "function-type interface" for the DFS
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  ///algorithm, which is convenient in the simplier cases and it can be
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  ///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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#ifdef DOXYGEN
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  template <typename GR,
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            typename TR>
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#else
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  template <typename GR=ListDigraph,
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            typename TR=DfsDefaultTraits<GR> >
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#endif
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  class Dfs {
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  public:
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    ///The type of the digraph the algorithm runs on.
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    typedef typename TR::Digraph Digraph;
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    ///\brief The type of the map that stores the predecessor arcs of the
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    ///DFS paths.
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    typedef typename TR::PredMap PredMap;
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    ///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 map that indicates which nodes are reached.
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    typedef typename TR::ReachedMap ReachedMap;
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    ///The type of the map that indicates which nodes are processed.
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    typedef typename TR::ProcessedMap ProcessedMap;
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    ///The type of the paths.
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    typedef PredMapPath<Digraph, PredMap> Path;
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    ///The \ref DfsDefaultTraits "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 *G;
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    //Pointer to the map of predecessor 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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    //Pointer to the map of reached status of the nodes.
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    ReachedMap *_reached;
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    //Indicates if _reached is locally allocated (true) or not.
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    bool local_reached;
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    //Pointer to the map of processed status of the nodes.
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    ProcessedMap *_processed;
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    //Indicates if _processed is locally allocated (true) or not.
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    bool local_processed;
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    std::vector<typename Digraph::OutArcIt> _stack;
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    int _stack_head;
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    //Creates the maps if necessary.
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    void create_maps()
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    {
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      if(!_pred) {
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        local_pred = true;
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        _pred = Traits::createPredMap(*G);
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      }
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      if(!_dist) {
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        local_dist = true;
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        _dist = Traits::createDistMap(*G);
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      }
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      if(!_reached) {
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        local_reached = true;
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        _reached = Traits::createReachedMap(*G);
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      }
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      if(!_processed) {
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        local_processed = true;
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        _processed = Traits::createProcessedMap(*G);
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      }
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    }
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  protected:
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    Dfs() {}
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  public:
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    typedef Dfs 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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      {
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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 meet the \ref concepts::WriteMap "WriteMap" concept.
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    template <class T>
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    struct SetPredMap : public Dfs<Digraph, SetPredMapTraits<T> > {
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      typedef Dfs<Digraph, 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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      {
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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 meet the \ref concepts::WriteMap "WriteMap" concept.
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    template <class T>
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    struct SetDistMap : public Dfs< Digraph, SetDistMapTraits<T> > {
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      typedef Dfs<Digraph, SetDistMapTraits<T> > Create;
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    };
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    template <class T>
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    struct SetReachedMapTraits : public Traits {
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      typedef T ReachedMap;
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      static ReachedMap *createReachedMap(const Digraph &)
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      {
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        LEMON_ASSERT(false, "ReachedMap 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 ReachedMap type.
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    ///
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    ///\ref named-templ-param "Named parameter" for setting
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    ///\c ReachedMap type.
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    ///It must meet the \ref concepts::ReadWriteMap "ReadWriteMap" concept.
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    template <class T>
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    struct SetReachedMap : public Dfs< Digraph, SetReachedMapTraits<T> > {
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      typedef Dfs< Digraph, SetReachedMapTraits<T> > Create;
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    };
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    template <class T>
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    struct SetProcessedMapTraits : public Traits {
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      typedef T ProcessedMap;
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      static ProcessedMap *createProcessedMap(const Digraph &)
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      {
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        LEMON_ASSERT(false, "ProcessedMap 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 ProcessedMap type.
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    ///
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    ///\ref named-templ-param "Named parameter" for setting
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    ///\c ProcessedMap type.
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    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
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    template <class T>
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    struct SetProcessedMap : public Dfs< Digraph, SetProcessedMapTraits<T> > {
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      typedef Dfs< Digraph, SetProcessedMapTraits<T> > Create;
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    };
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    struct SetStandardProcessedMapTraits : public Traits {
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      typedef typename Digraph::template NodeMap<bool> ProcessedMap;
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      static ProcessedMap *createProcessedMap(const Digraph &g)
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      {
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        return new ProcessedMap(g);
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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 ProcessedMap type to be <tt>Digraph::NodeMap<bool></tt>.
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    ///
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    ///\ref named-templ-param "Named parameter" for setting
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    ///\c ProcessedMap type to be <tt>Digraph::NodeMap<bool></tt>.
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    ///If you don't set it explicitly, it will be automatically allocated.
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    struct SetStandardProcessedMap :
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      public Dfs< Digraph, SetStandardProcessedMapTraits > {
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      typedef Dfs< Digraph, SetStandardProcessedMapTraits > Create;
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    };
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    ///@}
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  public:
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    ///Constructor.
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    ///Constructor.
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    ///\param g The digraph the algorithm runs on.
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    Dfs(const Digraph &g) :
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      G(&g),
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      _pred(NULL), local_pred(false),
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      _dist(NULL), local_dist(false),
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      _reached(NULL), local_reached(false),
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      _processed(NULL), local_processed(false)
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    { }
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    ///Destructor.
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    ~Dfs()
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    {
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      if(local_pred) delete _pred;
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      if(local_dist) delete _dist;
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      if(local_reached) delete _reached;
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      if(local_processed) delete _processed;
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    }
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    ///Sets the map that stores the predecessor arcs.
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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(Node) "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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    Dfs &predMap(PredMap &m)
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    {
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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 = &m;
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      return *this;
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    }
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    ///Sets the map that indicates which nodes are reached.
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    ///Sets the map that indicates which nodes are reached.
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    ///If you don't use this function before calling \ref run(Node) "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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    Dfs &reachedMap(ReachedMap &m)
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    {
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      if(local_reached) {
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        delete _reached;
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        local_reached=false;
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      }
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      _reached = &m;
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      return *this;
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    }
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    ///Sets the map that indicates which nodes are processed.
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    ///Sets the map that indicates which nodes are processed.
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    ///If you don't use this function before calling \ref run(Node) "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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    Dfs &processedMap(ProcessedMap &m)
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    {
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      if(local_processed) {
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        delete _processed;
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        local_processed=false;
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      }
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      _processed = &m;
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      return *this;
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    }
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    ///Sets the map that stores the distances of the nodes.
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    ///Sets the map that stores the distances of the nodes calculated by
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    ///the algorithm.
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    ///If you don't use this function before calling \ref run(Node) "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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    Dfs &distMap(DistMap &m)
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    {
alpar@100
   401
      if(local_dist) {
alpar@209
   402
        delete _dist;
alpar@209
   403
        local_dist=false;
alpar@100
   404
      }
alpar@100
   405
      _dist = &m;
alpar@100
   406
      return *this;
alpar@100
   407
    }
alpar@100
   408
kpeter@244
   409
  public:
alpar@100
   410
kpeter@421
   411
    ///\name Execution Control
kpeter@421
   412
    ///The simplest way to execute the DFS algorithm is to use one of the
kpeter@421
   413
    ///member functions called \ref run(Node) "run()".\n
kpeter@421
   414
    ///If you need more control on the execution, first you have to call
kpeter@421
   415
    ///\ref init(), then you can add a source node with \ref addSource()
kpeter@421
   416
    ///and perform the actual computation with \ref start().
kpeter@421
   417
    ///This procedure can be repeated if there are nodes that have not
kpeter@421
   418
    ///been reached.
alpar@100
   419
alpar@100
   420
    ///@{
alpar@100
   421
kpeter@421
   422
    ///\brief Initializes the internal data structures.
kpeter@421
   423
    ///
alpar@100
   424
    ///Initializes the internal data structures.
alpar@100
   425
    void init()
alpar@100
   426
    {
alpar@100
   427
      create_maps();
alpar@100
   428
      _stack.resize(countNodes(*G));
alpar@100
   429
      _stack_head=-1;
alpar@100
   430
      for ( NodeIt u(*G) ; u!=INVALID ; ++u ) {
alpar@209
   431
        _pred->set(u,INVALID);
alpar@209
   432
        _reached->set(u,false);
alpar@209
   433
        _processed->set(u,false);
alpar@100
   434
      }
alpar@100
   435
    }
alpar@209
   436
alpar@100
   437
    ///Adds a new source node.
alpar@100
   438
alpar@100
   439
    ///Adds a new source node to the set of nodes to be processed.
alpar@100
   440
    ///
kpeter@421
   441
    ///\pre The stack must be empty. Otherwise the algorithm gives
kpeter@421
   442
    ///wrong results. (One of the outgoing arcs of all the source nodes
kpeter@421
   443
    ///except for the last one will not be visited and distances will
kpeter@421
   444
    ///also be wrong.)
alpar@100
   445
    void addSource(Node s)
alpar@100
   446
    {
kpeter@244
   447
      LEMON_DEBUG(emptyQueue(), "The stack is not empty.");
alpar@100
   448
      if(!(*_reached)[s])
alpar@209
   449
        {
alpar@209
   450
          _reached->set(s,true);
alpar@209
   451
          _pred->set(s,INVALID);
alpar@209
   452
          OutArcIt e(*G,s);
alpar@209
   453
          if(e!=INVALID) {
alpar@209
   454
            _stack[++_stack_head]=e;
alpar@209
   455
            _dist->set(s,_stack_head);
alpar@209
   456
          }
alpar@209
   457
          else {
alpar@209
   458
            _processed->set(s,true);
alpar@209
   459
            _dist->set(s,0);
alpar@209
   460
          }
alpar@209
   461
        }
alpar@100
   462
    }
alpar@209
   463
alpar@100
   464
    ///Processes the next arc.
alpar@100
   465
alpar@100
   466
    ///Processes the next arc.
alpar@100
   467
    ///
alpar@100
   468
    ///\return The processed arc.
alpar@100
   469
    ///
kpeter@244
   470
    ///\pre The stack must not be empty.
alpar@100
   471
    Arc processNextArc()
alpar@209
   472
    {
alpar@100
   473
      Node m;
alpar@100
   474
      Arc e=_stack[_stack_head];
alpar@100
   475
      if(!(*_reached)[m=G->target(e)]) {
alpar@209
   476
        _pred->set(m,e);
alpar@209
   477
        _reached->set(m,true);
alpar@209
   478
        ++_stack_head;
alpar@209
   479
        _stack[_stack_head] = OutArcIt(*G, m);
alpar@209
   480
        _dist->set(m,_stack_head);
alpar@100
   481
      }
alpar@100
   482
      else {
alpar@209
   483
        m=G->source(e);
alpar@209
   484
        ++_stack[_stack_head];
alpar@100
   485
      }
alpar@100
   486
      while(_stack_head>=0 && _stack[_stack_head]==INVALID) {
alpar@209
   487
        _processed->set(m,true);
alpar@209
   488
        --_stack_head;
alpar@209
   489
        if(_stack_head>=0) {
alpar@209
   490
          m=G->source(_stack[_stack_head]);
alpar@209
   491
          ++_stack[_stack_head];
alpar@209
   492
        }
alpar@100
   493
      }
alpar@100
   494
      return e;
alpar@100
   495
    }
kpeter@244
   496
alpar@100
   497
    ///Next arc to be processed.
alpar@100
   498
alpar@100
   499
    ///Next arc to be processed.
alpar@100
   500
    ///
kpeter@244
   501
    ///\return The next arc to be processed or \c INVALID if the stack
kpeter@244
   502
    ///is empty.
kpeter@244
   503
    OutArcIt nextArc() const
alpar@209
   504
    {
alpar@100
   505
      return _stack_head>=0?_stack[_stack_head]:INVALID;
alpar@100
   506
    }
alpar@100
   507
kpeter@421
   508
    ///Returns \c false if there are nodes to be processed.
kpeter@421
   509
kpeter@421
   510
    ///Returns \c false if there are nodes to be processed
kpeter@421
   511
    ///in the queue (stack).
kpeter@244
   512
    bool emptyQueue() const { return _stack_head<0; }
kpeter@244
   513
alpar@100
   514
    ///Returns the number of the nodes to be processed.
alpar@209
   515
kpeter@421
   516
    ///Returns the number of the nodes to be processed
kpeter@421
   517
    ///in the queue (stack).
kpeter@244
   518
    int queueSize() const { return _stack_head+1; }
alpar@209
   519
alpar@100
   520
    ///Executes the algorithm.
alpar@100
   521
alpar@100
   522
    ///Executes the algorithm.
alpar@100
   523
    ///
kpeter@244
   524
    ///This method runs the %DFS algorithm from the root node
kpeter@244
   525
    ///in order to compute the DFS path to each node.
alpar@100
   526
    ///
kpeter@244
   527
    /// The algorithm computes
kpeter@244
   528
    ///- the %DFS tree,
kpeter@244
   529
    ///- the distance of each node from the root in the %DFS tree.
alpar@100
   530
    ///
kpeter@244
   531
    ///\pre init() must be called and a root node should be
kpeter@244
   532
    ///added with addSource() before using this function.
kpeter@244
   533
    ///
kpeter@244
   534
    ///\note <tt>d.start()</tt> is just a shortcut of the following code.
kpeter@244
   535
    ///\code
kpeter@244
   536
    ///  while ( !d.emptyQueue() ) {
kpeter@244
   537
    ///    d.processNextArc();
kpeter@244
   538
    ///  }
kpeter@244
   539
    ///\endcode
alpar@100
   540
    void start()
alpar@100
   541
    {
alpar@100
   542
      while ( !emptyQueue() ) processNextArc();
alpar@100
   543
    }
alpar@209
   544
kpeter@244
   545
    ///Executes the algorithm until the given target node is reached.
alpar@100
   546
kpeter@244
   547
    ///Executes the algorithm until the given target node is reached.
alpar@100
   548
    ///
kpeter@244
   549
    ///This method runs the %DFS algorithm from the root node
kpeter@286
   550
    ///in order to compute the DFS path to \c t.
alpar@100
   551
    ///
kpeter@244
   552
    ///The algorithm computes
kpeter@286
   553
    ///- the %DFS path to \c t,
kpeter@286
   554
    ///- the distance of \c t from the root in the %DFS tree.
alpar@100
   555
    ///
kpeter@244
   556
    ///\pre init() must be called and a root node should be
kpeter@244
   557
    ///added with addSource() before using this function.
kpeter@286
   558
    void start(Node t)
alpar@100
   559
    {
kpeter@286
   560
      while ( !emptyQueue() && G->target(_stack[_stack_head])!=t )
alpar@209
   561
        processNextArc();
alpar@100
   562
    }
alpar@209
   563
alpar@100
   564
    ///Executes the algorithm until a condition is met.
alpar@100
   565
alpar@100
   566
    ///Executes the algorithm until a condition is met.
alpar@100
   567
    ///
kpeter@244
   568
    ///This method runs the %DFS algorithm from the root node
kpeter@244
   569
    ///until an arc \c a with <tt>am[a]</tt> true is found.
alpar@100
   570
    ///
kpeter@244
   571
    ///\param am A \c bool (or convertible) arc map. The algorithm
kpeter@244
   572
    ///will stop when it reaches an arc \c a with <tt>am[a]</tt> true.
alpar@100
   573
    ///
kpeter@244
   574
    ///\return The reached arc \c a with <tt>am[a]</tt> true or
alpar@100
   575
    ///\c INVALID if no such arc was found.
alpar@100
   576
    ///
kpeter@244
   577
    ///\pre init() must be called and a root node should be
kpeter@244
   578
    ///added with addSource() before using this function.
kpeter@244
   579
    ///
kpeter@244
   580
    ///\warning Contrary to \ref Bfs and \ref Dijkstra, \c am is an arc map,
alpar@100
   581
    ///not a node map.
kpeter@244
   582
    template<class ArcBoolMap>
kpeter@244
   583
    Arc start(const ArcBoolMap &am)
alpar@100
   584
    {
kpeter@244
   585
      while ( !emptyQueue() && !am[_stack[_stack_head]] )
alpar@100
   586
        processNextArc();
alpar@100
   587
      return emptyQueue() ? INVALID : _stack[_stack_head];
alpar@100
   588
    }
alpar@100
   589
kpeter@286
   590
    ///Runs the algorithm from the given source node.
alpar@209
   591
kpeter@244
   592
    ///This method runs the %DFS algorithm from node \c s
kpeter@244
   593
    ///in order to compute the DFS path to each node.
alpar@100
   594
    ///
kpeter@244
   595
    ///The algorithm computes
kpeter@244
   596
    ///- the %DFS tree,
kpeter@244
   597
    ///- the distance of each node from the root in the %DFS tree.
kpeter@244
   598
    ///
kpeter@244
   599
    ///\note <tt>d.run(s)</tt> is just a shortcut of the following code.
alpar@100
   600
    ///\code
alpar@100
   601
    ///  d.init();
kpeter@244
   602
    ///  d.addSource(s);
kpeter@244
   603
    ///  d.start();
kpeter@244
   604
    ///\endcode
kpeter@244
   605
    void run(Node s) {
kpeter@244
   606
      init();
kpeter@244
   607
      addSource(s);
kpeter@244
   608
      start();
kpeter@244
   609
    }
kpeter@244
   610
kpeter@244
   611
    ///Finds the %DFS path between \c s and \c t.
kpeter@244
   612
kpeter@244
   613
    ///This method runs the %DFS algorithm from node \c s
kpeter@286
   614
    ///in order to compute the DFS path to node \c t
kpeter@286
   615
    ///(it stops searching when \c t is processed)
kpeter@244
   616
    ///
kpeter@286
   617
    ///\return \c true if \c t is reachable form \c s.
kpeter@244
   618
    ///
kpeter@244
   619
    ///\note Apart from the return value, <tt>d.run(s,t)</tt> is
kpeter@244
   620
    ///just a shortcut of the following code.
kpeter@244
   621
    ///\code
kpeter@244
   622
    ///  d.init();
kpeter@244
   623
    ///  d.addSource(s);
kpeter@244
   624
    ///  d.start(t);
kpeter@244
   625
    ///\endcode
kpeter@286
   626
    bool run(Node s,Node t) {
kpeter@244
   627
      init();
kpeter@244
   628
      addSource(s);
kpeter@244
   629
      start(t);
kpeter@286
   630
      return reached(t);
kpeter@244
   631
    }
kpeter@244
   632
kpeter@244
   633
    ///Runs the algorithm to visit all nodes in the digraph.
kpeter@244
   634
kpeter@244
   635
    ///This method runs the %DFS algorithm in order to compute the
kpeter@244
   636
    ///%DFS path to each node.
kpeter@244
   637
    ///
kpeter@244
   638
    ///The algorithm computes
kpeter@421
   639
    ///- the %DFS tree (forest),
kpeter@421
   640
    ///- the distance of each node from the root(s) in the %DFS tree.
kpeter@244
   641
    ///
kpeter@244
   642
    ///\note <tt>d.run()</tt> is just a shortcut of the following code.
kpeter@244
   643
    ///\code
kpeter@244
   644
    ///  d.init();
kpeter@244
   645
    ///  for (NodeIt n(digraph); n != INVALID; ++n) {
kpeter@244
   646
    ///    if (!d.reached(n)) {
kpeter@244
   647
    ///      d.addSource(n);
alpar@100
   648
    ///      d.start();
alpar@100
   649
    ///    }
alpar@100
   650
    ///  }
alpar@100
   651
    ///\endcode
alpar@100
   652
    void run() {
alpar@100
   653
      init();
alpar@100
   654
      for (NodeIt it(*G); it != INVALID; ++it) {
alpar@100
   655
        if (!reached(it)) {
alpar@100
   656
          addSource(it);
alpar@100
   657
          start();
alpar@100
   658
        }
alpar@100
   659
      }
alpar@100
   660
    }
alpar@100
   661
alpar@100
   662
    ///@}
alpar@100
   663
alpar@100
   664
    ///\name Query Functions
kpeter@421
   665
    ///The results of the DFS algorithm can be obtained using these
alpar@100
   666
    ///functions.\n
kpeter@421
   667
    ///Either \ref run(Node) "run()" or \ref start() should be called
kpeter@421
   668
    ///before using them.
alpar@209
   669
alpar@100
   670
    ///@{
alpar@100
   671
kpeter@244
   672
    ///The DFS path to a node.
alpar@100
   673
kpeter@244
   674
    ///Returns the DFS path to a node.
kpeter@244
   675
    ///
kpeter@421
   676
    ///\warning \c t should be reached from the root(s).
kpeter@244
   677
    ///
kpeter@421
   678
    ///\pre Either \ref run(Node) "run()" or \ref init()
kpeter@421
   679
    ///must be called before using this function.
kpeter@244
   680
    Path path(Node t) const { return Path(*G, *_pred, t); }
alpar@209
   681
kpeter@421
   682
    ///The distance of a node from the root(s).
alpar@100
   683
kpeter@421
   684
    ///Returns the distance of a node from the root(s).
kpeter@244
   685
    ///
kpeter@421
   686
    ///\warning If node \c v is not reached from the root(s), then
kpeter@244
   687
    ///the return value of this function is undefined.
kpeter@244
   688
    ///
kpeter@421
   689
    ///\pre Either \ref run(Node) "run()" or \ref init()
kpeter@421
   690
    ///must be called before using this function.
alpar@100
   691
    int dist(Node v) const { return (*_dist)[v]; }
alpar@100
   692
kpeter@244
   693
    ///Returns the 'previous arc' of the %DFS tree for a node.
alpar@100
   694
kpeter@244
   695
    ///This function returns the 'previous arc' of the %DFS tree for the
kpeter@421
   696
    ///node \c v, i.e. it returns the last arc of a %DFS path from a
kpeter@421
   697
    ///root to \c v. It is \c INVALID if \c v is not reached from the
kpeter@421
   698
    ///root(s) or if \c v is a root.
kpeter@244
   699
    ///
kpeter@244
   700
    ///The %DFS tree used here is equal to the %DFS tree used in
alpar@100
   701
    ///\ref predNode().
kpeter@244
   702
    ///
kpeter@421
   703
    ///\pre Either \ref run(Node) "run()" or \ref init()
kpeter@421
   704
    ///must be called before using this function.
alpar@100
   705
    Arc predArc(Node v) const { return (*_pred)[v];}
alpar@100
   706
alpar@100
   707
    ///Returns the 'previous node' of the %DFS tree.
alpar@100
   708
kpeter@244
   709
    ///This function returns the 'previous node' of the %DFS
kpeter@244
   710
    ///tree for the node \c v, i.e. it returns the last but one node
kpeter@421
   711
    ///from a %DFS path from a root to \c v. It is \c INVALID
kpeter@421
   712
    ///if \c v is not reached from the root(s) or if \c v is a root.
kpeter@244
   713
    ///
kpeter@244
   714
    ///The %DFS tree used here is equal to the %DFS tree used in
kpeter@244
   715
    ///\ref predArc().
kpeter@244
   716
    ///
kpeter@421
   717
    ///\pre Either \ref run(Node) "run()" or \ref init()
kpeter@421
   718
    ///must be called before using this function.
alpar@100
   719
    Node predNode(Node v) const { return (*_pred)[v]==INVALID ? INVALID:
alpar@209
   720
                                  G->source((*_pred)[v]); }
alpar@209
   721
kpeter@244
   722
    ///\brief Returns a const reference to the node map that stores the
kpeter@244
   723
    ///distances of the nodes.
kpeter@244
   724
    ///
kpeter@244
   725
    ///Returns a const reference to the node map that stores the
kpeter@244
   726
    ///distances of the nodes calculated by the algorithm.
kpeter@244
   727
    ///
kpeter@421
   728
    ///\pre Either \ref run(Node) "run()" or \ref init()
kpeter@244
   729
    ///must be called before using this function.
alpar@100
   730
    const DistMap &distMap() const { return *_dist;}
alpar@209
   731
kpeter@244
   732
    ///\brief Returns a const reference to the node map that stores the
kpeter@244
   733
    ///predecessor arcs.
kpeter@244
   734
    ///
kpeter@244
   735
    ///Returns a const reference to the node map that stores the predecessor
kpeter@244
   736
    ///arcs, which form the DFS tree.
kpeter@244
   737
    ///
kpeter@421
   738
    ///\pre Either \ref run(Node) "run()" or \ref init()
alpar@100
   739
    ///must be called before using this function.
alpar@100
   740
    const PredMap &predMap() const { return *_pred;}
alpar@209
   741
kpeter@421
   742
    ///Checks if a node is reached from the root(s).
alpar@100
   743
kpeter@421
   744
    ///Returns \c true if \c v is reached from the root(s).
kpeter@421
   745
    ///
kpeter@421
   746
    ///\pre Either \ref run(Node) "run()" or \ref init()
alpar@100
   747
    ///must be called before using this function.
kpeter@244
   748
    bool reached(Node v) const { return (*_reached)[v]; }
alpar@209
   749
alpar@100
   750
    ///@}
alpar@100
   751
  };
alpar@100
   752
kpeter@244
   753
  ///Default traits class of dfs() function.
alpar@100
   754
kpeter@244
   755
  ///Default traits class of dfs() function.
kpeter@157
   756
  ///\tparam GR Digraph type.
alpar@100
   757
  template<class GR>
alpar@100
   758
  struct DfsWizardDefaultTraits
alpar@100
   759
  {
kpeter@244
   760
    ///The type of the digraph the algorithm runs on.
alpar@100
   761
    typedef GR Digraph;
kpeter@244
   762
kpeter@244
   763
    ///\brief The type of the map that stores the predecessor
alpar@100
   764
    ///arcs of the %DFS paths.
alpar@209
   765
    ///
kpeter@244
   766
    ///The type of the map that stores the predecessor
alpar@100
   767
    ///arcs of the %DFS paths.
alpar@100
   768
    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
kpeter@278
   769
    typedef typename Digraph::template NodeMap<typename Digraph::Arc> PredMap;
kpeter@301
   770
    ///Instantiates a PredMap.
alpar@209
   771
kpeter@301
   772
    ///This function instantiates a PredMap.
kpeter@244
   773
    ///\param g is the digraph, to which we would like to define the
kpeter@301
   774
    ///PredMap.
kpeter@244
   775
    static PredMap *createPredMap(const Digraph &g)
alpar@100
   776
    {
kpeter@278
   777
      return new PredMap(g);
alpar@100
   778
    }
alpar@100
   779
alpar@100
   780
    ///The type of the map that indicates which nodes are processed.
alpar@209
   781
alpar@100
   782
    ///The type of the map that indicates which nodes are processed.
alpar@100
   783
    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
kpeter@278
   784
    ///By default it is a NullMap.
alpar@100
   785
    typedef NullMap<typename Digraph::Node,bool> ProcessedMap;
kpeter@301
   786
    ///Instantiates a ProcessedMap.
alpar@209
   787
kpeter@301
   788
    ///This function instantiates a ProcessedMap.
alpar@100
   789
    ///\param g is the digraph, to which
kpeter@301
   790
    ///we would like to define the ProcessedMap.
alpar@100
   791
#ifdef DOXYGEN
kpeter@244
   792
    static ProcessedMap *createProcessedMap(const Digraph &g)
alpar@100
   793
#else
kpeter@244
   794
    static ProcessedMap *createProcessedMap(const Digraph &)
alpar@100
   795
#endif
alpar@100
   796
    {
alpar@100
   797
      return new ProcessedMap();
alpar@100
   798
    }
kpeter@244
   799
alpar@100
   800
    ///The type of the map that indicates which nodes are reached.
alpar@209
   801
alpar@100
   802
    ///The type of the map that indicates which nodes are reached.
kpeter@244
   803
    ///It must meet the \ref concepts::ReadWriteMap "ReadWriteMap" concept.
alpar@100
   804
    typedef typename Digraph::template NodeMap<bool> ReachedMap;
kpeter@301
   805
    ///Instantiates a ReachedMap.
alpar@209
   806
kpeter@301
   807
    ///This function instantiates a ReachedMap.
kpeter@244
   808
    ///\param g is the digraph, to which
kpeter@301
   809
    ///we would like to define the ReachedMap.
kpeter@244
   810
    static ReachedMap *createReachedMap(const Digraph &g)
alpar@100
   811
    {
kpeter@244
   812
      return new ReachedMap(g);
alpar@100
   813
    }
alpar@209
   814
kpeter@244
   815
    ///The type of the map that stores the distances of the nodes.
kpeter@244
   816
kpeter@244
   817
    ///The type of the map that stores the distances of the nodes.
alpar@100
   818
    ///It must meet the \ref concepts::WriteMap "WriteMap" concept.
kpeter@278
   819
    typedef typename Digraph::template NodeMap<int> DistMap;
kpeter@301
   820
    ///Instantiates a DistMap.
alpar@209
   821
kpeter@301
   822
    ///This function instantiates a DistMap.
alpar@210
   823
    ///\param g is the digraph, to which we would like to define
kpeter@301
   824
    ///the DistMap
kpeter@244
   825
    static DistMap *createDistMap(const Digraph &g)
alpar@100
   826
    {
kpeter@278
   827
      return new DistMap(g);
alpar@100
   828
    }
kpeter@278
   829
kpeter@278
   830
    ///The type of the DFS paths.
kpeter@278
   831
kpeter@278
   832
    ///The type of the DFS paths.
kpeter@278
   833
    ///It must meet the \ref concepts::Path "Path" concept.
kpeter@278
   834
    typedef lemon::Path<Digraph> Path;
alpar@100
   835
  };
alpar@209
   836
kpeter@313
   837
  /// Default traits class used by DfsWizard
alpar@100
   838
alpar@100
   839
  /// To make it easier to use Dfs algorithm
kpeter@244
   840
  /// we have created a wizard class.
alpar@100
   841
  /// This \ref DfsWizard class needs default traits,
kpeter@244
   842
  /// as well as the \ref Dfs class.
alpar@100
   843
  /// The \ref DfsWizardBase is a class to be the default traits of the
alpar@100
   844
  /// \ref DfsWizard class.
alpar@100
   845
  template<class GR>
alpar@100
   846
  class DfsWizardBase : public DfsWizardDefaultTraits<GR>
alpar@100
   847
  {
alpar@100
   848
alpar@100
   849
    typedef DfsWizardDefaultTraits<GR> Base;
alpar@100
   850
  protected:
kpeter@244
   851
    //The type of the nodes in the digraph.
alpar@100
   852
    typedef typename Base::Digraph::Node Node;
alpar@100
   853
kpeter@244
   854
    //Pointer to the digraph the algorithm runs on.
alpar@100
   855
    void *_g;
kpeter@244
   856
    //Pointer to the map of reached nodes.
alpar@100
   857
    void *_reached;
kpeter@244
   858
    //Pointer to the map of processed nodes.
alpar@100
   859
    void *_processed;
kpeter@244
   860
    //Pointer to the map of predecessors arcs.
alpar@100
   861
    void *_pred;
kpeter@244
   862
    //Pointer to the map of distances.
alpar@100
   863
    void *_dist;
kpeter@278
   864
    //Pointer to the DFS path to the target node.
kpeter@278
   865
    void *_path;
kpeter@278
   866
    //Pointer to the distance of the target node.
kpeter@278
   867
    int *_di;
alpar@209
   868
alpar@100
   869
    public:
alpar@100
   870
    /// Constructor.
alpar@209
   871
alpar@100
   872
    /// This constructor does not require parameters, therefore it initiates
kpeter@278
   873
    /// all of the attributes to \c 0.
alpar@100
   874
    DfsWizardBase() : _g(0), _reached(0), _processed(0), _pred(0),
kpeter@278
   875
                      _dist(0), _path(0), _di(0) {}
alpar@100
   876
alpar@100
   877
    /// Constructor.
alpar@209
   878
kpeter@278
   879
    /// This constructor requires one parameter,
kpeter@278
   880
    /// others are initiated to \c 0.
kpeter@244
   881
    /// \param g The digraph the algorithm runs on.
kpeter@278
   882
    DfsWizardBase(const GR &g) :
alpar@209
   883
      _g(reinterpret_cast<void*>(const_cast<GR*>(&g))),
kpeter@278
   884
      _reached(0), _processed(0), _pred(0), _dist(0),  _path(0), _di(0) {}
alpar@100
   885
alpar@100
   886
  };
alpar@209
   887
kpeter@278
   888
  /// Auxiliary class for the function-type interface of DFS algorithm.
alpar@100
   889
kpeter@278
   890
  /// This auxiliary class is created to implement the
kpeter@278
   891
  /// \ref dfs() "function-type interface" of \ref Dfs algorithm.
kpeter@421
   892
  /// It does not have own \ref run(Node) "run()" method, it uses the
kpeter@421
   893
  /// functions and features of the plain \ref Dfs.
alpar@100
   894
  ///
kpeter@278
   895
  /// This class should only be used through the \ref dfs() function,
kpeter@278
   896
  /// which makes it easier to use the algorithm.
alpar@100
   897
  template<class TR>
alpar@100
   898
  class DfsWizard : public TR
alpar@100
   899
  {
alpar@100
   900
    typedef TR Base;
alpar@100
   901
kpeter@244
   902
    ///The type of the digraph the algorithm runs on.
alpar@100
   903
    typedef typename TR::Digraph Digraph;
kpeter@244
   904
alpar@100
   905
    typedef typename Digraph::Node Node;
alpar@100
   906
    typedef typename Digraph::NodeIt NodeIt;
alpar@100
   907
    typedef typename Digraph::Arc Arc;
alpar@100
   908
    typedef typename Digraph::OutArcIt OutArcIt;
alpar@209
   909
kpeter@244
   910
    ///\brief The type of the map that stores the predecessor
kpeter@278
   911
    ///arcs of the DFS paths.
kpeter@244
   912
    typedef typename TR::PredMap PredMap;
kpeter@244
   913
    ///\brief The type of the map that stores the distances of the nodes.
kpeter@244
   914
    typedef typename TR::DistMap DistMap;
kpeter@244
   915
    ///\brief The type of the map that indicates which nodes are reached.
alpar@100
   916
    typedef typename TR::ReachedMap ReachedMap;
kpeter@244
   917
    ///\brief The type of the map that indicates which nodes are processed.
alpar@100
   918
    typedef typename TR::ProcessedMap ProcessedMap;
kpeter@278
   919
    ///The type of the DFS paths
kpeter@278
   920
    typedef typename TR::Path Path;
alpar@100
   921
alpar@100
   922
  public:
kpeter@244
   923
alpar@100
   924
    /// Constructor.
alpar@100
   925
    DfsWizard() : TR() {}
alpar@100
   926
alpar@100
   927
    /// Constructor that requires parameters.
alpar@100
   928
alpar@100
   929
    /// Constructor that requires parameters.
alpar@100
   930
    /// These parameters will be the default values for the traits class.
kpeter@278
   931
    /// \param g The digraph the algorithm runs on.
kpeter@278
   932
    DfsWizard(const Digraph &g) :
kpeter@278
   933
      TR(g) {}
alpar@100
   934
alpar@100
   935
    ///Copy constructor
alpar@100
   936
    DfsWizard(const TR &b) : TR(b) {}
alpar@100
   937
alpar@100
   938
    ~DfsWizard() {}
alpar@100
   939
kpeter@278
   940
    ///Runs DFS algorithm from the given source node.
alpar@209
   941
kpeter@278
   942
    ///This method runs DFS algorithm from node \c s
kpeter@278
   943
    ///in order to compute the DFS path to each node.
kpeter@278
   944
    void run(Node s)
kpeter@278
   945
    {
kpeter@278
   946
      Dfs<Digraph,TR> alg(*reinterpret_cast<const Digraph*>(Base::_g));
kpeter@278
   947
      if (Base::_pred)
kpeter@278
   948
        alg.predMap(*reinterpret_cast<PredMap*>(Base::_pred));
kpeter@278
   949
      if (Base::_dist)
kpeter@278
   950
        alg.distMap(*reinterpret_cast<DistMap*>(Base::_dist));
kpeter@278
   951
      if (Base::_reached)
kpeter@278
   952
        alg.reachedMap(*reinterpret_cast<ReachedMap*>(Base::_reached));
kpeter@278
   953
      if (Base::_processed)
kpeter@278
   954
        alg.processedMap(*reinterpret_cast<ProcessedMap*>(Base::_processed));
kpeter@278
   955
      if (s!=INVALID)
kpeter@278
   956
        alg.run(s);
kpeter@278
   957
      else
kpeter@278
   958
        alg.run();
kpeter@278
   959
    }
kpeter@278
   960
kpeter@278
   961
    ///Finds the DFS path between \c s and \c t.
kpeter@278
   962
kpeter@278
   963
    ///This method runs DFS algorithm from node \c s
kpeter@278
   964
    ///in order to compute the DFS path to node \c t
kpeter@278
   965
    ///(it stops searching when \c t is processed).
kpeter@278
   966
    ///
kpeter@278
   967
    ///\return \c true if \c t is reachable form \c s.
kpeter@278
   968
    bool run(Node s, Node t)
kpeter@278
   969
    {
kpeter@278
   970
      Dfs<Digraph,TR> alg(*reinterpret_cast<const Digraph*>(Base::_g));
kpeter@278
   971
      if (Base::_pred)
kpeter@278
   972
        alg.predMap(*reinterpret_cast<PredMap*>(Base::_pred));
kpeter@278
   973
      if (Base::_dist)
kpeter@278
   974
        alg.distMap(*reinterpret_cast<DistMap*>(Base::_dist));
kpeter@278
   975
      if (Base::_reached)
kpeter@278
   976
        alg.reachedMap(*reinterpret_cast<ReachedMap*>(Base::_reached));
kpeter@278
   977
      if (Base::_processed)
kpeter@278
   978
        alg.processedMap(*reinterpret_cast<ProcessedMap*>(Base::_processed));
kpeter@278
   979
      alg.run(s,t);
kpeter@278
   980
      if (Base::_path)
kpeter@278
   981
        *reinterpret_cast<Path*>(Base::_path) = alg.path(t);
kpeter@278
   982
      if (Base::_di)
kpeter@278
   983
        *Base::_di = alg.dist(t);
kpeter@278
   984
      return alg.reached(t);
kpeter@278
   985
      }
kpeter@278
   986
kpeter@278
   987
    ///Runs DFS algorithm to visit all nodes in the digraph.
kpeter@278
   988
kpeter@278
   989
    ///This method runs DFS algorithm in order to compute
kpeter@278
   990
    ///the DFS path to each node.
alpar@100
   991
    void run()
alpar@100
   992
    {
kpeter@278
   993
      run(INVALID);
kpeter@244
   994
    }
kpeter@244
   995
alpar@100
   996
    template<class T>
kpeter@257
   997
    struct SetPredMapBase : public Base {
alpar@100
   998
      typedef T PredMap;
alpar@100
   999
      static PredMap *createPredMap(const Digraph &) { return 0; };
kpeter@257
  1000
      SetPredMapBase(const TR &b) : TR(b) {}
alpar@100
  1001
    };
kpeter@278
  1002
    ///\brief \ref named-func-param "Named parameter"
kpeter@301
  1003
    ///for setting PredMap object.
alpar@100
  1004
    ///
kpeter@278
  1005
    ///\ref named-func-param "Named parameter"
kpeter@301
  1006
    ///for setting PredMap object.
alpar@100
  1007
    template<class T>
kpeter@257
  1008
    DfsWizard<SetPredMapBase<T> > predMap(const T &t)
alpar@100
  1009
    {
alpar@100
  1010
      Base::_pred=reinterpret_cast<void*>(const_cast<T*>(&t));
kpeter@257
  1011
      return DfsWizard<SetPredMapBase<T> >(*this);
alpar@100
  1012
    }
alpar@209
  1013
alpar@100
  1014
    template<class T>
kpeter@257
  1015
    struct SetReachedMapBase : public Base {
alpar@100
  1016
      typedef T ReachedMap;
alpar@100
  1017
      static ReachedMap *createReachedMap(const Digraph &) { return 0; };
kpeter@257
  1018
      SetReachedMapBase(const TR &b) : TR(b) {}
alpar@100
  1019
    };
kpeter@278
  1020
    ///\brief \ref named-func-param "Named parameter"
kpeter@301
  1021
    ///for setting ReachedMap object.
alpar@100
  1022
    ///
kpeter@278
  1023
    /// \ref named-func-param "Named parameter"
kpeter@301
  1024
    ///for setting ReachedMap object.
alpar@100
  1025
    template<class T>
kpeter@257
  1026
    DfsWizard<SetReachedMapBase<T> > reachedMap(const T &t)
alpar@100
  1027
    {
deba@158
  1028
      Base::_reached=reinterpret_cast<void*>(const_cast<T*>(&t));
kpeter@257
  1029
      return DfsWizard<SetReachedMapBase<T> >(*this);
alpar@100
  1030
    }
alpar@209
  1031
alpar@100
  1032
    template<class T>
kpeter@278
  1033
    struct SetDistMapBase : public Base {
kpeter@278
  1034
      typedef T DistMap;
kpeter@278
  1035
      static DistMap *createDistMap(const Digraph &) { return 0; };
kpeter@278
  1036
      SetDistMapBase(const TR &b) : TR(b) {}
kpeter@278
  1037
    };
kpeter@278
  1038
    ///\brief \ref named-func-param "Named parameter"
kpeter@301
  1039
    ///for setting DistMap object.
kpeter@278
  1040
    ///
kpeter@278
  1041
    /// \ref named-func-param "Named parameter"
kpeter@301
  1042
    ///for setting DistMap object.
kpeter@278
  1043
    template<class T>
kpeter@278
  1044
    DfsWizard<SetDistMapBase<T> > distMap(const T &t)
kpeter@278
  1045
    {
kpeter@278
  1046
      Base::_dist=reinterpret_cast<void*>(const_cast<T*>(&t));
kpeter@278
  1047
      return DfsWizard<SetDistMapBase<T> >(*this);
kpeter@278
  1048
    }
kpeter@278
  1049
kpeter@278
  1050
    template<class T>
kpeter@257
  1051
    struct SetProcessedMapBase : public Base {
alpar@100
  1052
      typedef T ProcessedMap;
alpar@100
  1053
      static ProcessedMap *createProcessedMap(const Digraph &) { return 0; };
kpeter@257
  1054
      SetProcessedMapBase(const TR &b) : TR(b) {}
alpar@100
  1055
    };
kpeter@278
  1056
    ///\brief \ref named-func-param "Named parameter"
kpeter@301
  1057
    ///for setting ProcessedMap object.
alpar@100
  1058
    ///
kpeter@278
  1059
    /// \ref named-func-param "Named parameter"
kpeter@301
  1060
    ///for setting ProcessedMap object.
alpar@100
  1061
    template<class T>
kpeter@257
  1062
    DfsWizard<SetProcessedMapBase<T> > processedMap(const T &t)
alpar@100
  1063
    {
deba@158
  1064
      Base::_processed=reinterpret_cast<void*>(const_cast<T*>(&t));
kpeter@257
  1065
      return DfsWizard<SetProcessedMapBase<T> >(*this);
alpar@100
  1066
    }
alpar@209
  1067
alpar@100
  1068
    template<class T>
kpeter@278
  1069
    struct SetPathBase : public Base {
kpeter@278
  1070
      typedef T Path;
kpeter@278
  1071
      SetPathBase(const TR &b) : TR(b) {}
alpar@100
  1072
    };
kpeter@278
  1073
    ///\brief \ref named-func-param "Named parameter"
kpeter@278
  1074
    ///for getting the DFS path to the target node.
alpar@100
  1075
    ///
kpeter@278
  1076
    ///\ref named-func-param "Named parameter"
kpeter@278
  1077
    ///for getting the DFS path to the target node.
alpar@100
  1078
    template<class T>
kpeter@278
  1079
    DfsWizard<SetPathBase<T> > path(const T &t)
alpar@100
  1080
    {
kpeter@278
  1081
      Base::_path=reinterpret_cast<void*>(const_cast<T*>(&t));
kpeter@278
  1082
      return DfsWizard<SetPathBase<T> >(*this);
kpeter@278
  1083
    }
kpeter@278
  1084
kpeter@278
  1085
    ///\brief \ref named-func-param "Named parameter"
kpeter@278
  1086
    ///for getting the distance of the target node.
kpeter@278
  1087
    ///
kpeter@278
  1088
    ///\ref named-func-param "Named parameter"
kpeter@278
  1089
    ///for getting the distance of the target node.
kpeter@278
  1090
    DfsWizard dist(const int &d)
kpeter@278
  1091
    {
kpeter@278
  1092
      Base::_di=const_cast<int*>(&d);
kpeter@278
  1093
      return *this;
alpar@100
  1094
    }
alpar@209
  1095
alpar@100
  1096
  };
alpar@209
  1097
kpeter@278
  1098
  ///Function-type interface for DFS algorithm.
alpar@100
  1099
alpar@100
  1100
  ///\ingroup search
kpeter@278
  1101
  ///Function-type interface for DFS algorithm.
alpar@100
  1102
  ///
kpeter@278
  1103
  ///This function also has several \ref named-func-param "named parameters",
alpar@100
  1104
  ///they are declared as the members of class \ref DfsWizard.
kpeter@278
  1105
  ///The following examples show how to use these parameters.
alpar@100
  1106
  ///\code
kpeter@278
  1107
  ///  // Compute the DFS tree
kpeter@278
  1108
  ///  dfs(g).predMap(preds).distMap(dists).run(s);
kpeter@278
  1109
  ///
kpeter@278
  1110
  ///  // Compute the DFS path from s to t
kpeter@278
  1111
  ///  bool reached = dfs(g).path(p).dist(d).run(s,t);
alpar@100
  1112
  ///\endcode
kpeter@421
  1113
  ///\warning Don't forget to put the \ref DfsWizard::run(Node) "run()"
alpar@100
  1114
  ///to the end of the parameter list.
alpar@100
  1115
  ///\sa DfsWizard
alpar@100
  1116
  ///\sa Dfs
alpar@100
  1117
  template<class GR>
alpar@100
  1118
  DfsWizard<DfsWizardBase<GR> >
kpeter@278
  1119
  dfs(const GR &digraph)
alpar@100
  1120
  {
kpeter@278
  1121
    return DfsWizard<DfsWizardBase<GR> >(digraph);
alpar@100
  1122
  }
alpar@100
  1123
alpar@100
  1124
#ifdef DOXYGEN
kpeter@244
  1125
  /// \brief Visitor class for DFS.
alpar@209
  1126
  ///
kpeter@244
  1127
  /// This class defines the interface of the DfsVisit events, and
kpeter@244
  1128
  /// it could be the base of a real visitor class.
kpeter@525
  1129
  template <typename GR>
alpar@100
  1130
  struct DfsVisitor {
kpeter@525
  1131
    typedef GR Digraph;
alpar@100
  1132
    typedef typename Digraph::Arc Arc;
alpar@100
  1133
    typedef typename Digraph::Node Node;
kpeter@244
  1134
    /// \brief Called for the source node of the DFS.
alpar@209
  1135
    ///
kpeter@244
  1136
    /// This function is called for the source node of the DFS.
kpeter@244
  1137
    void start(const Node& node) {}
kpeter@244
  1138
    /// \brief Called when the source node is leaved.
kpeter@244
  1139
    ///
kpeter@244
  1140
    /// This function is called when the source node is leaved.
kpeter@244
  1141
    void stop(const Node& node) {}
kpeter@244
  1142
    /// \brief Called when a node is reached first time.
kpeter@244
  1143
    ///
kpeter@244
  1144
    /// This function is called when a node is reached first time.
kpeter@244
  1145
    void reach(const Node& node) {}
kpeter@244
  1146
    /// \brief Called when an arc reaches a new node.
kpeter@244
  1147
    ///
kpeter@244
  1148
    /// This function is called when the DFS finds an arc whose target node
kpeter@244
  1149
    /// is not reached yet.
alpar@100
  1150
    void discover(const Arc& arc) {}
kpeter@244
  1151
    /// \brief Called when an arc is examined but its target node is
alpar@100
  1152
    /// already discovered.
alpar@209
  1153
    ///
kpeter@244
  1154
    /// This function is called when an arc is examined but its target node is
alpar@100
  1155
    /// already discovered.
alpar@100
  1156
    void examine(const Arc& arc) {}
kpeter@244
  1157
    /// \brief Called when the DFS steps back from a node.
alpar@209
  1158
    ///
kpeter@244
  1159
    /// This function is called when the DFS steps back from a node.
kpeter@244
  1160
    void leave(const Node& node) {}
kpeter@244
  1161
    /// \brief Called when the DFS steps back on an arc.
alpar@209
  1162
    ///
kpeter@244
  1163
    /// This function is called when the DFS steps back on an arc.
kpeter@244
  1164
    void backtrack(const Arc& arc) {}
alpar@100
  1165
  };
alpar@100
  1166
#else
kpeter@525
  1167
  template <typename GR>
alpar@100
  1168
  struct DfsVisitor {
kpeter@525
  1169
    typedef GR Digraph;
alpar@100
  1170
    typedef typename Digraph::Arc Arc;
alpar@100
  1171
    typedef typename Digraph::Node Node;
alpar@100
  1172
    void start(const Node&) {}
alpar@100
  1173
    void stop(const Node&) {}
kpeter@244
  1174
    void reach(const Node&) {}
kpeter@244
  1175
    void discover(const Arc&) {}
kpeter@244
  1176
    void examine(const Arc&) {}
kpeter@244
  1177
    void leave(const Node&) {}
kpeter@244
  1178
    void backtrack(const Arc&) {}
alpar@100
  1179
alpar@100
  1180
    template <typename _Visitor>
alpar@100
  1181
    struct Constraints {
alpar@100
  1182
      void constraints() {
alpar@209
  1183
        Arc arc;
alpar@209
  1184
        Node node;
alpar@209
  1185
        visitor.start(node);
alpar@209
  1186
        visitor.stop(arc);
kpeter@244
  1187
        visitor.reach(node);
kpeter@244
  1188
        visitor.discover(arc);
kpeter@244
  1189
        visitor.examine(arc);
kpeter@244
  1190
        visitor.leave(node);
kpeter@244
  1191
        visitor.backtrack(arc);
alpar@100
  1192
      }
alpar@100
  1193
      _Visitor& visitor;
alpar@100
  1194
    };
alpar@100
  1195
  };
alpar@100
  1196
#endif
alpar@100
  1197
alpar@100
  1198
  /// \brief Default traits class of DfsVisit class.
alpar@100
  1199
  ///
alpar@100
  1200
  /// Default traits class of DfsVisit class.
kpeter@244
  1201
  /// \tparam _Digraph The type of the digraph the algorithm runs on.
kpeter@525
  1202
  template<class GR>
alpar@100
  1203
  struct DfsVisitDefaultTraits {
alpar@100
  1204
kpeter@244
  1205
    /// \brief The type of the digraph the algorithm runs on.
kpeter@525
  1206
    typedef GR Digraph;
alpar@100
  1207
alpar@100
  1208
    /// \brief The type of the map that indicates which nodes are reached.
alpar@209
  1209
    ///
alpar@100
  1210
    /// The type of the map that indicates which nodes are reached.
kpeter@244
  1211
    /// It must meet the \ref concepts::ReadWriteMap "ReadWriteMap" concept.
alpar@100
  1212
    typedef typename Digraph::template NodeMap<bool> ReachedMap;
alpar@100
  1213
kpeter@301
  1214
    /// \brief Instantiates a ReachedMap.
alpar@100
  1215
    ///
kpeter@301
  1216
    /// This function instantiates a ReachedMap.
alpar@100
  1217
    /// \param digraph is the digraph, to which
kpeter@301
  1218
    /// we would like to define the ReachedMap.
alpar@100
  1219
    static ReachedMap *createReachedMap(const Digraph &digraph) {
alpar@100
  1220
      return new ReachedMap(digraph);
alpar@100
  1221
    }
alpar@100
  1222
alpar@100
  1223
  };
alpar@209
  1224
alpar@100
  1225
  /// \ingroup search
kpeter@244
  1226
  ///
kpeter@525
  1227
  /// \brief DFS algorithm class with visitor interface.
kpeter@244
  1228
  ///
kpeter@525
  1229
  /// This class provides an efficient implementation of the DFS algorithm
alpar@100
  1230
  /// with visitor interface.
alpar@100
  1231
  ///
kpeter@525
  1232
  /// The DfsVisit class provides an alternative interface to the Dfs
alpar@100
  1233
  /// class. It works with callback mechanism, the DfsVisit object calls
kpeter@244
  1234
  /// the member functions of the \c Visitor class on every DFS event.
alpar@100
  1235
  ///
kpeter@252
  1236
  /// This interface of the DFS algorithm should be used in special cases
kpeter@252
  1237
  /// when extra actions have to be performed in connection with certain
kpeter@252
  1238
  /// events of the DFS algorithm. Otherwise consider to use Dfs or dfs()
kpeter@252
  1239
  /// instead.
kpeter@252
  1240
  ///
kpeter@525
  1241
  /// \tparam GR The type of the digraph the algorithm runs on.
kpeter@525
  1242
  /// The default type is \ref ListDigraph.
kpeter@525
  1243
  /// The value of GR is not used directly by \ref DfsVisit,
kpeter@525
  1244
  /// it is only passed to \ref DfsVisitDefaultTraits.
kpeter@525
  1245
  /// \tparam VS The Visitor type that is used by the algorithm.
kpeter@525
  1246
  /// \ref DfsVisitor "DfsVisitor<GR>" is an empty visitor, which
kpeter@244
  1247
  /// does not observe the DFS events. If you want to observe the DFS
kpeter@244
  1248
  /// events, you should implement your own visitor class.
kpeter@525
  1249
  /// \tparam TR Traits class to set various data types used by the
alpar@100
  1250
  /// algorithm. The default traits class is
kpeter@525
  1251
  /// \ref DfsVisitDefaultTraits "DfsVisitDefaultTraits<GR>".
alpar@100
  1252
  /// See \ref DfsVisitDefaultTraits for the documentation of
kpeter@244
  1253
  /// a DFS visit traits class.
alpar@100
  1254
#ifdef DOXYGEN
kpeter@525
  1255
  template <typename GR, typename VS, typename TR>
alpar@100
  1256
#else
kpeter@525
  1257
  template <typename GR = ListDigraph,
kpeter@525
  1258
            typename VS = DfsVisitor<GR>,
kpeter@525
  1259
            typename TR = DfsVisitDefaultTraits<GR> >
alpar@100
  1260
#endif
alpar@100
  1261
  class DfsVisit {
alpar@100
  1262
  public:
alpar@209
  1263
kpeter@244
  1264
    ///The traits class.
kpeter@525
  1265
    typedef TR Traits;
alpar@100
  1266
kpeter@244
  1267
    ///The type of the digraph the algorithm runs on.
alpar@100
  1268
    typedef typename Traits::Digraph Digraph;
alpar@100
  1269
kpeter@244
  1270
    ///The visitor type used by the algorithm.
kpeter@525
  1271
    typedef VS Visitor;
alpar@100
  1272
kpeter@244
  1273
    ///The type of the map that indicates which nodes are reached.
alpar@100
  1274
    typedef typename Traits::ReachedMap ReachedMap;
alpar@100
  1275
alpar@100
  1276
  private:
alpar@100
  1277
alpar@100
  1278
    typedef typename Digraph::Node Node;
alpar@100
  1279
    typedef typename Digraph::NodeIt NodeIt;
alpar@100
  1280
    typedef typename Digraph::Arc Arc;
alpar@100
  1281
    typedef typename Digraph::OutArcIt OutArcIt;
alpar@100
  1282
kpeter@244
  1283
    //Pointer to the underlying digraph.
alpar@100
  1284
    const Digraph *_digraph;
kpeter@244
  1285
    //Pointer to the visitor object.
alpar@100
  1286
    Visitor *_visitor;
kpeter@244
  1287
    //Pointer to the map of reached status of the nodes.
alpar@100
  1288
    ReachedMap *_reached;
kpeter@244
  1289
    //Indicates if _reached is locally allocated (true) or not.
alpar@100
  1290
    bool local_reached;
alpar@100
  1291
alpar@100
  1292
    std::vector<typename Digraph::Arc> _stack;
alpar@100
  1293
    int _stack_head;
alpar@100
  1294
alpar@280
  1295
    //Creates the maps if necessary.
alpar@100
  1296
    void create_maps() {
alpar@100
  1297
      if(!_reached) {
alpar@209
  1298
        local_reached = true;
alpar@209
  1299
        _reached = Traits::createReachedMap(*_digraph);
alpar@100
  1300
      }
alpar@100
  1301
    }
alpar@100
  1302
alpar@100
  1303
  protected:
alpar@100
  1304
alpar@100
  1305
    DfsVisit() {}
alpar@209
  1306
alpar@100
  1307
  public:
alpar@100
  1308
alpar@100
  1309
    typedef DfsVisit Create;
alpar@100
  1310
kpeter@421
  1311
    /// \name Named Template Parameters
alpar@100
  1312
alpar@100
  1313
    ///@{
alpar@100
  1314
    template <class T>
kpeter@257
  1315
    struct SetReachedMapTraits : public Traits {
alpar@100
  1316
      typedef T ReachedMap;
alpar@100
  1317
      static ReachedMap *createReachedMap(const Digraph &digraph) {
deba@290
  1318
        LEMON_ASSERT(false, "ReachedMap is not initialized");
deba@290
  1319
        return 0; // ignore warnings
alpar@100
  1320
      }
alpar@100
  1321
    };
alpar@209
  1322
    /// \brief \ref named-templ-param "Named parameter" for setting
kpeter@244
  1323
    /// ReachedMap type.
alpar@100
  1324
    ///
kpeter@244
  1325
    /// \ref named-templ-param "Named parameter" for setting ReachedMap type.
alpar@100
  1326
    template <class T>
kpeter@257
  1327
    struct SetReachedMap : public DfsVisit< Digraph, Visitor,
kpeter@257
  1328
                                            SetReachedMapTraits<T> > {
kpeter@257
  1329
      typedef DfsVisit< Digraph, Visitor, SetReachedMapTraits<T> > Create;
alpar@100
  1330
    };
alpar@100
  1331
    ///@}
alpar@100
  1332
alpar@209
  1333
  public:
alpar@209
  1334
alpar@100
  1335
    /// \brief Constructor.
alpar@100
  1336
    ///
alpar@100
  1337
    /// Constructor.
alpar@100
  1338
    ///
kpeter@244
  1339
    /// \param digraph The digraph the algorithm runs on.
kpeter@244
  1340
    /// \param visitor The visitor object of the algorithm.
alpar@209
  1341
    DfsVisit(const Digraph& digraph, Visitor& visitor)
alpar@100
  1342
      : _digraph(&digraph), _visitor(&visitor),
alpar@209
  1343
        _reached(0), local_reached(false) {}
alpar@209
  1344
alpar@100
  1345
    /// \brief Destructor.
alpar@100
  1346
    ~DfsVisit() {
alpar@100
  1347
      if(local_reached) delete _reached;
alpar@100
  1348
    }
alpar@100
  1349
kpeter@244
  1350
    /// \brief Sets the map that indicates which nodes are reached.
alpar@100
  1351
    ///
kpeter@244
  1352
    /// Sets the map that indicates which nodes are reached.
kpeter@421
  1353
    /// If you don't use this function before calling \ref run(Node) "run()"
kpeter@421
  1354
    /// or \ref init(), an instance will be allocated automatically.
kpeter@421
  1355
    /// The destructor deallocates this automatically allocated map,
kpeter@421
  1356
    /// of course.
alpar@100
  1357
    /// \return <tt> (*this) </tt>
alpar@100
  1358
    DfsVisit &reachedMap(ReachedMap &m) {
alpar@100
  1359
      if(local_reached) {
alpar@209
  1360
        delete _reached;
alpar@209
  1361
        local_reached=false;
alpar@100
  1362
      }
alpar@100
  1363
      _reached = &m;
alpar@100
  1364
      return *this;
alpar@100
  1365
    }
alpar@100
  1366
alpar@100
  1367
  public:
kpeter@244
  1368
kpeter@421
  1369
    /// \name Execution Control
kpeter@421
  1370
    /// The simplest way to execute the DFS algorithm is to use one of the
kpeter@421
  1371
    /// member functions called \ref run(Node) "run()".\n
kpeter@421
  1372
    /// If you need more control on the execution, first you have to call
kpeter@421
  1373
    /// \ref init(), then you can add a source node with \ref addSource()
kpeter@421
  1374
    /// and perform the actual computation with \ref start().
kpeter@421
  1375
    /// This procedure can be repeated if there are nodes that have not
kpeter@421
  1376
    /// been reached.
alpar@100
  1377
alpar@100
  1378
    /// @{
kpeter@244
  1379
alpar@100
  1380
    /// \brief Initializes the internal data structures.
alpar@100
  1381
    ///
alpar@100
  1382
    /// Initializes the internal data structures.
alpar@100
  1383
    void init() {
alpar@100
  1384
      create_maps();
alpar@100
  1385
      _stack.resize(countNodes(*_digraph));
alpar@100
  1386
      _stack_head = -1;
alpar@100
  1387
      for (NodeIt u(*_digraph) ; u != INVALID ; ++u) {
alpar@209
  1388
        _reached->set(u, false);
alpar@100
  1389
      }
alpar@100
  1390
    }
alpar@209
  1391
kpeter@421
  1392
    /// \brief Adds a new source node.
alpar@100
  1393
    ///
kpeter@421
  1394
    /// Adds a new source node to the set of nodes to be processed.
kpeter@244
  1395
    ///
kpeter@421
  1396
    /// \pre The stack must be empty. Otherwise the algorithm gives
kpeter@421
  1397
    /// wrong results. (One of the outgoing arcs of all the source nodes
kpeter@421
  1398
    /// except for the last one will not be visited and distances will
kpeter@421
  1399
    /// also be wrong.)
kpeter@244
  1400
    void addSource(Node s)
kpeter@244
  1401
    {
kpeter@244
  1402
      LEMON_DEBUG(emptyQueue(), "The stack is not empty.");
alpar@100
  1403
      if(!(*_reached)[s]) {
alpar@209
  1404
          _reached->set(s,true);
alpar@209
  1405
          _visitor->start(s);
alpar@209
  1406
          _visitor->reach(s);
alpar@209
  1407
          Arc e;
alpar@209
  1408
          _digraph->firstOut(e, s);
alpar@209
  1409
          if (e != INVALID) {
alpar@209
  1410
            _stack[++_stack_head] = e;
alpar@209
  1411
          } else {
alpar@209
  1412
            _visitor->leave(s);
deba@435
  1413
            _visitor->stop(s);
alpar@209
  1414
          }
alpar@209
  1415
        }
alpar@100
  1416
    }
alpar@209
  1417
alpar@100
  1418
    /// \brief Processes the next arc.
alpar@100
  1419
    ///
alpar@100
  1420
    /// Processes the next arc.
alpar@100
  1421
    ///
alpar@100
  1422
    /// \return The processed arc.
alpar@100
  1423
    ///
kpeter@244
  1424
    /// \pre The stack must not be empty.
alpar@209
  1425
    Arc processNextArc() {
alpar@100
  1426
      Arc e = _stack[_stack_head];
alpar@100
  1427
      Node m = _digraph->target(e);
alpar@100
  1428
      if(!(*_reached)[m]) {
alpar@209
  1429
        _visitor->discover(e);
alpar@209
  1430
        _visitor->reach(m);
alpar@209
  1431
        _reached->set(m, true);
alpar@209
  1432
        _digraph->firstOut(_stack[++_stack_head], m);
alpar@100
  1433
      } else {
alpar@209
  1434
        _visitor->examine(e);
alpar@209
  1435
        m = _digraph->source(e);
alpar@209
  1436
        _digraph->nextOut(_stack[_stack_head]);
alpar@100
  1437
      }
alpar@100
  1438
      while (_stack_head>=0 && _stack[_stack_head] == INVALID) {
alpar@209
  1439
        _visitor->leave(m);
alpar@209
  1440
        --_stack_head;
alpar@209
  1441
        if (_stack_head >= 0) {
alpar@209
  1442
          _visitor->backtrack(_stack[_stack_head]);
alpar@209
  1443
          m = _digraph->source(_stack[_stack_head]);
alpar@209
  1444
          _digraph->nextOut(_stack[_stack_head]);
alpar@209
  1445
        } else {
alpar@209
  1446
          _visitor->stop(m);
alpar@209
  1447
        }
alpar@100
  1448
      }
alpar@100
  1449
      return e;
alpar@100
  1450
    }
alpar@100
  1451
alpar@100
  1452
    /// \brief Next arc to be processed.
alpar@100
  1453
    ///
alpar@100
  1454
    /// Next arc to be processed.
alpar@100
  1455
    ///
alpar@100
  1456
    /// \return The next arc to be processed or INVALID if the stack is
alpar@100
  1457
    /// empty.
kpeter@244
  1458
    Arc nextArc() const {
alpar@100
  1459
      return _stack_head >= 0 ? _stack[_stack_head] : INVALID;
alpar@100
  1460
    }
alpar@100
  1461
alpar@100
  1462
    /// \brief Returns \c false if there are nodes
kpeter@244
  1463
    /// to be processed.
alpar@100
  1464
    ///
alpar@100
  1465
    /// Returns \c false if there are nodes
kpeter@244
  1466
    /// to be processed in the queue (stack).
kpeter@244
  1467
    bool emptyQueue() const { return _stack_head < 0; }
alpar@100
  1468
alpar@100
  1469
    /// \brief Returns the number of the nodes to be processed.
alpar@100
  1470
    ///
kpeter@244
  1471
    /// Returns the number of the nodes to be processed in the queue (stack).
kpeter@244
  1472
    int queueSize() const { return _stack_head + 1; }
alpar@209
  1473
alpar@100
  1474
    /// \brief Executes the algorithm.
alpar@100
  1475
    ///
alpar@100
  1476
    /// Executes the algorithm.
alpar@100
  1477
    ///
kpeter@244
  1478
    /// This method runs the %DFS algorithm from the root node
kpeter@244
  1479
    /// in order to compute the %DFS path to each node.
kpeter@244
  1480
    ///
kpeter@244
  1481
    /// The algorithm computes
kpeter@244
  1482
    /// - the %DFS tree,
kpeter@244
  1483
    /// - the distance of each node from the root in the %DFS tree.
kpeter@244
  1484
    ///
kpeter@244
  1485
    /// \pre init() must be called and a root node should be
kpeter@244
  1486
    /// added with addSource() before using this function.
kpeter@244
  1487
    ///
kpeter@244
  1488
    /// \note <tt>d.start()</tt> is just a shortcut of the following code.
kpeter@244
  1489
    /// \code
kpeter@244
  1490
    ///   while ( !d.emptyQueue() ) {
kpeter@244
  1491
    ///     d.processNextArc();
kpeter@244
  1492
    ///   }
kpeter@244
  1493
    /// \endcode
alpar@100
  1494
    void start() {
alpar@100
  1495
      while ( !emptyQueue() ) processNextArc();
alpar@100
  1496
    }
alpar@209
  1497
kpeter@244
  1498
    /// \brief Executes the algorithm until the given target node is reached.
alpar@100
  1499
    ///
kpeter@244
  1500
    /// Executes the algorithm until the given target node is reached.
alpar@100
  1501
    ///
kpeter@244
  1502
    /// This method runs the %DFS algorithm from the root node
kpeter@286
  1503
    /// in order to compute the DFS path to \c t.
kpeter@244
  1504
    ///
kpeter@244
  1505
    /// The algorithm computes
kpeter@286
  1506
    /// - the %DFS path to \c t,
kpeter@286
  1507
    /// - the distance of \c t from the root in the %DFS tree.
kpeter@244
  1508
    ///
kpeter@244
  1509
    /// \pre init() must be called and a root node should be added
alpar@100
  1510
    /// with addSource() before using this function.
kpeter@286
  1511
    void start(Node t) {
kpeter@286
  1512
      while ( !emptyQueue() && _digraph->target(_stack[_stack_head]) != t )
alpar@209
  1513
        processNextArc();
alpar@100
  1514
    }
alpar@209
  1515
alpar@100
  1516
    /// \brief Executes the algorithm until a condition is met.
alpar@100
  1517
    ///
alpar@100
  1518
    /// Executes the algorithm until a condition is met.
alpar@100
  1519
    ///
kpeter@244
  1520
    /// This method runs the %DFS algorithm from the root node
kpeter@244
  1521
    /// until an arc \c a with <tt>am[a]</tt> true is found.
kpeter@244
  1522
    ///
kpeter@244
  1523
    /// \param am A \c bool (or convertible) arc map. The algorithm
kpeter@244
  1524
    /// will stop when it reaches an arc \c a with <tt>am[a]</tt> true.
kpeter@244
  1525
    ///
kpeter@244
  1526
    /// \return The reached arc \c a with <tt>am[a]</tt> true or
kpeter@244
  1527
    /// \c INVALID if no such arc was found.
kpeter@244
  1528
    ///
kpeter@244
  1529
    /// \pre init() must be called and a root node should be added
alpar@100
  1530
    /// with addSource() before using this function.
alpar@100
  1531
    ///
kpeter@244
  1532
    /// \warning Contrary to \ref Bfs and \ref Dijkstra, \c am is an arc map,
alpar@100
  1533
    /// not a node map.
kpeter@244
  1534
    template <typename AM>
kpeter@244
  1535
    Arc start(const AM &am) {
kpeter@244
  1536
      while ( !emptyQueue() && !am[_stack[_stack_head]] )
alpar@100
  1537
        processNextArc();
alpar@100
  1538
      return emptyQueue() ? INVALID : _stack[_stack_head];
alpar@100
  1539
    }
alpar@100
  1540
kpeter@286
  1541
    /// \brief Runs the algorithm from the given source node.
alpar@100
  1542
    ///
kpeter@244
  1543
    /// This method runs the %DFS algorithm from node \c s.
kpeter@244
  1544
    /// in order to compute the DFS path to each node.
kpeter@244
  1545
    ///
kpeter@244
  1546
    /// The algorithm computes
kpeter@244
  1547
    /// - the %DFS tree,
kpeter@244
  1548
    /// - the distance of each node from the root in the %DFS tree.
kpeter@244
  1549
    ///
kpeter@244
  1550
    /// \note <tt>d.run(s)</tt> is just a shortcut of the following code.
alpar@100
  1551
    ///\code
alpar@100
  1552
    ///   d.init();
alpar@100
  1553
    ///   d.addSource(s);
alpar@100
  1554
    ///   d.start();
alpar@100
  1555
    ///\endcode
alpar@100
  1556
    void run(Node s) {
alpar@100
  1557
      init();
alpar@100
  1558
      addSource(s);
alpar@100
  1559
      start();
alpar@100
  1560
    }
alpar@100
  1561
kpeter@244
  1562
    /// \brief Finds the %DFS path between \c s and \c t.
kpeter@244
  1563
kpeter@244
  1564
    /// This method runs the %DFS algorithm from node \c s
kpeter@286
  1565
    /// in order to compute the DFS path to node \c t
kpeter@286
  1566
    /// (it stops searching when \c t is processed).
kpeter@244
  1567
    ///
kpeter@286
  1568
    /// \return \c true if \c t is reachable form \c s.
kpeter@244
  1569
    ///
kpeter@244
  1570
    /// \note Apart from the return value, <tt>d.run(s,t)</tt> is
kpeter@244
  1571
    /// just a shortcut of the following code.
kpeter@244
  1572
    ///\code
kpeter@244
  1573
    ///   d.init();
kpeter@244
  1574
    ///   d.addSource(s);
kpeter@244
  1575
    ///   d.start(t);
kpeter@244
  1576
    ///\endcode
kpeter@286
  1577
    bool run(Node s,Node t) {
kpeter@244
  1578
      init();
kpeter@244
  1579
      addSource(s);
kpeter@244
  1580
      start(t);
kpeter@286
  1581
      return reached(t);
kpeter@244
  1582
    }
kpeter@244
  1583
kpeter@244
  1584
    /// \brief Runs the algorithm to visit all nodes in the digraph.
alpar@209
  1585
alpar@100
  1586
    /// This method runs the %DFS algorithm in order to
kpeter@244
  1587
    /// compute the %DFS path to each node.
alpar@100
  1588
    ///
kpeter@244
  1589
    /// The algorithm computes
kpeter@421
  1590
    /// - the %DFS tree (forest),
kpeter@421
  1591
    /// - the distance of each node from the root(s) in the %DFS tree.
kpeter@244
  1592
    ///
kpeter@244
  1593
    /// \note <tt>d.run()</tt> is just a shortcut of the following code.
alpar@100
  1594
    ///\code
kpeter@244
  1595
    ///   d.init();
kpeter@244
  1596
    ///   for (NodeIt n(digraph); n != INVALID; ++n) {
kpeter@244
  1597
    ///     if (!d.reached(n)) {
kpeter@244
  1598
    ///       d.addSource(n);
kpeter@244
  1599
    ///       d.start();
kpeter@244
  1600
    ///     }
kpeter@244
  1601
    ///   }
alpar@100
  1602
    ///\endcode
alpar@100
  1603
    void run() {
alpar@100
  1604
      init();
alpar@100
  1605
      for (NodeIt it(*_digraph); it != INVALID; ++it) {
alpar@100
  1606
        if (!reached(it)) {
alpar@100
  1607
          addSource(it);
alpar@100
  1608
          start();
alpar@100
  1609
        }
alpar@100
  1610
      }
alpar@100
  1611
    }
kpeter@244
  1612
alpar@100
  1613
    ///@}
alpar@100
  1614
alpar@100
  1615
    /// \name Query Functions
kpeter@421
  1616
    /// The results of the DFS algorithm can be obtained using these
alpar@100
  1617
    /// functions.\n
kpeter@421
  1618
    /// Either \ref run(Node) "run()" or \ref start() should be called
kpeter@421
  1619
    /// before using them.
kpeter@421
  1620
alpar@100
  1621
    ///@{
kpeter@244
  1622
kpeter@421
  1623
    /// \brief Checks if a node is reached from the root(s).
alpar@100
  1624
    ///
kpeter@421
  1625
    /// Returns \c true if \c v is reached from the root(s).
kpeter@421
  1626
    ///
kpeter@421
  1627
    /// \pre Either \ref run(Node) "run()" or \ref init()
alpar@100
  1628
    /// must be called before using this function.
kpeter@437
  1629
    bool reached(Node v) const { return (*_reached)[v]; }
kpeter@244
  1630
alpar@100
  1631
    ///@}
kpeter@244
  1632
alpar@100
  1633
  };
alpar@100
  1634
alpar@100
  1635
} //END OF NAMESPACE LEMON
alpar@100
  1636
alpar@100
  1637
#endif