Port Euler walk tools from SVN -r3512 (#65)
authorAlpar Juttner <alpar@cs.elte.hu>
Mon, 23 Feb 2009 11:30:15 +0000 (2009-02-23)
changeset 52042d4b889903a
parent 519 c786cd201266
child 521 3af83b6be1df
Port Euler walk tools from SVN -r3512 (#65)
lemon/Makefile.am
lemon/euler.h
     1.1 --- a/lemon/Makefile.am	Mon Feb 23 11:58:39 2009 +0100
     1.2 +++ b/lemon/Makefile.am	Mon Feb 23 11:30:15 2009 +0000
     1.3 @@ -64,6 +64,7 @@
     1.4  	lemon/edge_set.h \
     1.5  	lemon/elevator.h \
     1.6  	lemon/error.h \
     1.7 +	lemon/euler.h \
     1.8  	lemon/full_graph.h \
     1.9  	lemon/glpk.h \
    1.10  	lemon/graph_to_eps.h \
     2.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     2.2 +++ b/lemon/euler.h	Mon Feb 23 11:30:15 2009 +0000
     2.3 @@ -0,0 +1,267 @@
     2.4 +/* -*- mode: C++; indent-tabs-mode: nil; -*-
     2.5 + *
     2.6 + * This file is a part of LEMON, a generic C++ optimization library.
     2.7 + *
     2.8 + * Copyright (C) 2003-2009
     2.9 + * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
    2.10 + * (Egervary Research Group on Combinatorial Optimization, EGRES).
    2.11 + *
    2.12 + * Permission to use, modify and distribute this software is granted
    2.13 + * provided that this copyright notice appears in all copies. For
    2.14 + * precise terms see the accompanying LICENSE file.
    2.15 + *
    2.16 + * This software is provided "AS IS" with no warranty of any kind,
    2.17 + * express or implied, and with no claim as to its suitability for any
    2.18 + * purpose.
    2.19 + *
    2.20 + */
    2.21 +
    2.22 +#ifndef LEMON_EULER_H
    2.23 +#define LEMON_EULER_H
    2.24 +
    2.25 +#include<lemon/core.h>
    2.26 +#include<lemon/adaptors.h>
    2.27 +#include<lemon/connectivity.h>
    2.28 +#include <list>
    2.29 +
    2.30 +/// \ingroup graph_prop
    2.31 +/// \file
    2.32 +/// \brief Euler tour
    2.33 +///
    2.34 +///This file provides an Euler tour iterator and ways to check
    2.35 +///if a digraph is euler.
    2.36 +
    2.37 +
    2.38 +namespace lemon {
    2.39 +
    2.40 +  ///Euler iterator for digraphs.
    2.41 +
    2.42 +  /// \ingroup graph_prop
    2.43 +  ///This iterator converts to the \c Arc type of the digraph and using
    2.44 +  ///operator ++, it provides an Euler tour of a \e directed
    2.45 +  ///graph (if there exists).
    2.46 +  ///
    2.47 +  ///For example
    2.48 +  ///if the given digraph is Euler (i.e it has only one nontrivial component
    2.49 +  ///and the in-degree is equal to the out-degree for all nodes),
    2.50 +  ///the following code will put the arcs of \c g
    2.51 +  ///to the vector \c et according to an
    2.52 +  ///Euler tour of \c g.
    2.53 +  ///\code
    2.54 +  ///  std::vector<ListDigraph::Arc> et;
    2.55 +  ///  for(DiEulerIt<ListDigraph> e(g),e!=INVALID;++e)
    2.56 +  ///    et.push_back(e);
    2.57 +  ///\endcode
    2.58 +  ///If \c g is not Euler then the resulted tour will not be full or closed.
    2.59 +  ///\sa EulerIt
    2.60 +  ///\todo Test required
    2.61 +  template<class Digraph>
    2.62 +  class DiEulerIt
    2.63 +  {
    2.64 +    typedef typename Digraph::Node Node;
    2.65 +    typedef typename Digraph::NodeIt NodeIt;
    2.66 +    typedef typename Digraph::Arc Arc;
    2.67 +    typedef typename Digraph::ArcIt ArcIt;
    2.68 +    typedef typename Digraph::OutArcIt OutArcIt;
    2.69 +    typedef typename Digraph::InArcIt InArcIt;
    2.70 +
    2.71 +    const Digraph &g;
    2.72 +    typename Digraph::template NodeMap<OutArcIt> nedge;
    2.73 +    std::list<Arc> euler;
    2.74 +
    2.75 +  public:
    2.76 +
    2.77 +    ///Constructor
    2.78 +
    2.79 +    ///\param _g A digraph.
    2.80 +    ///\param start The starting point of the tour. If it is not given
    2.81 +    ///       the tour will start from the first node.
    2.82 +    DiEulerIt(const Digraph &_g,typename Digraph::Node start=INVALID)
    2.83 +      : g(_g), nedge(g)
    2.84 +    {
    2.85 +      if(start==INVALID) start=NodeIt(g);
    2.86 +      for(NodeIt n(g);n!=INVALID;++n) nedge[n]=OutArcIt(g,n);
    2.87 +      while(nedge[start]!=INVALID) {
    2.88 +        euler.push_back(nedge[start]);
    2.89 +        Node next=g.target(nedge[start]);
    2.90 +        ++nedge[start];
    2.91 +        start=next;
    2.92 +      }
    2.93 +    }
    2.94 +
    2.95 +    ///Arc Conversion
    2.96 +    operator Arc() { return euler.empty()?INVALID:euler.front(); }
    2.97 +    bool operator==(Invalid) { return euler.empty(); }
    2.98 +    bool operator!=(Invalid) { return !euler.empty(); }
    2.99 +
   2.100 +    ///Next arc of the tour
   2.101 +    DiEulerIt &operator++() {
   2.102 +      Node s=g.target(euler.front());
   2.103 +      euler.pop_front();
   2.104 +      //This produces a warning.Strange.
   2.105 +      //std::list<Arc>::iterator next=euler.begin();
   2.106 +      typename std::list<Arc>::iterator next=euler.begin();
   2.107 +      while(nedge[s]!=INVALID) {
   2.108 +        euler.insert(next,nedge[s]);
   2.109 +        Node n=g.target(nedge[s]);
   2.110 +        ++nedge[s];
   2.111 +        s=n;
   2.112 +      }
   2.113 +      return *this;
   2.114 +    }
   2.115 +    ///Postfix incrementation
   2.116 +
   2.117 +    ///\warning This incrementation
   2.118 +    ///returns an \c Arc, not an \ref DiEulerIt, as one may
   2.119 +    ///expect.
   2.120 +    Arc operator++(int)
   2.121 +    {
   2.122 +      Arc e=*this;
   2.123 +      ++(*this);
   2.124 +      return e;
   2.125 +    }
   2.126 +  };
   2.127 +
   2.128 +  ///Euler iterator for graphs.
   2.129 +
   2.130 +  /// \ingroup graph_prop
   2.131 +  ///This iterator converts to the \c Arc (or \c Edge)
   2.132 +  ///type of the digraph and using
   2.133 +  ///operator ++, it provides an Euler tour of an undirected
   2.134 +  ///digraph (if there exists).
   2.135 +  ///
   2.136 +  ///For example
   2.137 +  ///if the given digraph if Euler (i.e it has only one nontrivial component
   2.138 +  ///and the degree of each node is even),
   2.139 +  ///the following code will print the arc IDs according to an
   2.140 +  ///Euler tour of \c g.
   2.141 +  ///\code
   2.142 +  ///  for(EulerIt<ListGraph> e(g),e!=INVALID;++e) {
   2.143 +  ///    std::cout << g.id(Edge(e)) << std::eol;
   2.144 +  ///  }
   2.145 +  ///\endcode
   2.146 +  ///Although the iterator provides an Euler tour of an graph,
   2.147 +  ///it still returns Arcs in order to indicate the direction of the tour.
   2.148 +  ///(But Arc will convert to Edges, of course).
   2.149 +  ///
   2.150 +  ///If \c g is not Euler then the resulted tour will not be full or closed.
   2.151 +  ///\sa EulerIt
   2.152 +  ///\todo Test required
   2.153 +  template<class Digraph>
   2.154 +  class EulerIt
   2.155 +  {
   2.156 +    typedef typename Digraph::Node Node;
   2.157 +    typedef typename Digraph::NodeIt NodeIt;
   2.158 +    typedef typename Digraph::Arc Arc;
   2.159 +    typedef typename Digraph::Edge Edge;
   2.160 +    typedef typename Digraph::ArcIt ArcIt;
   2.161 +    typedef typename Digraph::OutArcIt OutArcIt;
   2.162 +    typedef typename Digraph::InArcIt InArcIt;
   2.163 +
   2.164 +    const Digraph &g;
   2.165 +    typename Digraph::template NodeMap<OutArcIt> nedge;
   2.166 +    typename Digraph::template EdgeMap<bool> visited;
   2.167 +    std::list<Arc> euler;
   2.168 +
   2.169 +  public:
   2.170 +
   2.171 +    ///Constructor
   2.172 +
   2.173 +    ///\param _g An graph.
   2.174 +    ///\param start The starting point of the tour. If it is not given
   2.175 +    ///       the tour will start from the first node.
   2.176 +    EulerIt(const Digraph &_g,typename Digraph::Node start=INVALID)
   2.177 +      : g(_g), nedge(g), visited(g,false)
   2.178 +    {
   2.179 +      if(start==INVALID) start=NodeIt(g);
   2.180 +      for(NodeIt n(g);n!=INVALID;++n) nedge[n]=OutArcIt(g,n);
   2.181 +      while(nedge[start]!=INVALID) {
   2.182 +        euler.push_back(nedge[start]);
   2.183 +        visited[nedge[start]]=true;
   2.184 +        Node next=g.target(nedge[start]);
   2.185 +        ++nedge[start];
   2.186 +        start=next;
   2.187 +        while(nedge[start]!=INVALID && visited[nedge[start]]) ++nedge[start];
   2.188 +      }
   2.189 +    }
   2.190 +
   2.191 +    ///Arc Conversion
   2.192 +    operator Arc() const { return euler.empty()?INVALID:euler.front(); }
   2.193 +    ///Arc Conversion
   2.194 +    operator Edge() const { return euler.empty()?INVALID:euler.front(); }
   2.195 +    ///\e
   2.196 +    bool operator==(Invalid) const { return euler.empty(); }
   2.197 +    ///\e
   2.198 +    bool operator!=(Invalid) const { return !euler.empty(); }
   2.199 +
   2.200 +    ///Next arc of the tour
   2.201 +    EulerIt &operator++() {
   2.202 +      Node s=g.target(euler.front());
   2.203 +      euler.pop_front();
   2.204 +      typename std::list<Arc>::iterator next=euler.begin();
   2.205 +
   2.206 +      while(nedge[s]!=INVALID) {
   2.207 +        while(nedge[s]!=INVALID && visited[nedge[s]]) ++nedge[s];
   2.208 +        if(nedge[s]==INVALID) break;
   2.209 +        else {
   2.210 +          euler.insert(next,nedge[s]);
   2.211 +          visited[nedge[s]]=true;
   2.212 +          Node n=g.target(nedge[s]);
   2.213 +          ++nedge[s];
   2.214 +          s=n;
   2.215 +        }
   2.216 +      }
   2.217 +      return *this;
   2.218 +    }
   2.219 +
   2.220 +    ///Postfix incrementation
   2.221 +
   2.222 +    ///\warning This incrementation
   2.223 +    ///returns an \c Arc, not an \ref EulerIt, as one may
   2.224 +    ///expect.
   2.225 +    Arc operator++(int)
   2.226 +    {
   2.227 +      Arc e=*this;
   2.228 +      ++(*this);
   2.229 +      return e;
   2.230 +    }
   2.231 +  };
   2.232 +
   2.233 +
   2.234 +  ///Checks if the graph is Euler
   2.235 +
   2.236 +  /// \ingroup graph_prop
   2.237 +  ///Checks if the graph is Euler. It works for both directed and undirected
   2.238 +  ///graphs.
   2.239 +  ///\note By definition, a digraph is called \e Euler if
   2.240 +  ///and only if it is connected and the number of its incoming and outgoing
   2.241 +  ///arcs are the same for each node.
   2.242 +  ///Similarly, an undirected graph is called \e Euler if
   2.243 +  ///and only if it is connected and the number of incident arcs is even
   2.244 +  ///for each node. <em>Therefore, there are digraphs which are not Euler, but
   2.245 +  ///still have an Euler tour</em>.
   2.246 +  ///\todo Test required
   2.247 +  template<class Digraph>
   2.248 +#ifdef DOXYGEN
   2.249 +  bool
   2.250 +#else
   2.251 +  typename enable_if<UndirectedTagIndicator<Digraph>,bool>::type
   2.252 +  euler(const Digraph &g)
   2.253 +  {
   2.254 +    for(typename Digraph::NodeIt n(g);n!=INVALID;++n)
   2.255 +      if(countIncEdges(g,n)%2) return false;
   2.256 +    return connected(g);
   2.257 +  }
   2.258 +  template<class Digraph>
   2.259 +  typename disable_if<UndirectedTagIndicator<Digraph>,bool>::type
   2.260 +#endif
   2.261 +  euler(const Digraph &g)
   2.262 +  {
   2.263 +    for(typename Digraph::NodeIt n(g);n!=INVALID;++n)
   2.264 +      if(countInArcs(g,n)!=countOutArcs(g,n)) return false;
   2.265 +    return connected(Undirector<const Digraph>(g));
   2.266 +  }
   2.267 +
   2.268 +}
   2.269 +
   2.270 +#endif