Merge
authorAlpar Juttner <alpar@cs.elte.hu>
Wed, 04 Mar 2009 14:09:45 +0000
changeset 535d59dcc933e59
parent 530 fc6c7aab4b8d
parent 534 d6b40ebb2617
child 537 94387da47f79
Merge
     1.1 --- a/lemon/Makefile.am	Wed Mar 04 13:43:05 2009 +0000
     1.2 +++ b/lemon/Makefile.am	Wed Mar 04 14:09:45 2009 +0000
     1.3 @@ -68,6 +68,7 @@
     1.4  	lemon/euler.h \
     1.5  	lemon/full_graph.h \
     1.6  	lemon/glpk.h \
     1.7 +	lemon/gomory_hu.h \
     1.8  	lemon/graph_to_eps.h \
     1.9  	lemon/grid_graph.h \
    1.10  	lemon/hypercube_graph.h \
     2.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     2.2 +++ b/lemon/gomory_hu.h	Wed Mar 04 14:09:45 2009 +0000
     2.3 @@ -0,0 +1,551 @@
     2.4 +/* -*- C++ -*-
     2.5 + *
     2.6 + * This file is a part of LEMON, a generic C++ optimization library
     2.7 + *
     2.8 + * Copyright (C) 2003-2008
     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_GOMORY_HU_TREE_H
    2.23 +#define LEMON_GOMORY_HU_TREE_H
    2.24 +
    2.25 +#include <limits>
    2.26 +
    2.27 +#include <lemon/core.h>
    2.28 +#include <lemon/preflow.h>
    2.29 +#include <lemon/concept_check.h>
    2.30 +#include <lemon/concepts/maps.h>
    2.31 +
    2.32 +/// \ingroup min_cut
    2.33 +/// \file 
    2.34 +/// \brief Gomory-Hu cut tree in graphs.
    2.35 +
    2.36 +namespace lemon {
    2.37 +
    2.38 +  /// \ingroup min_cut
    2.39 +  ///
    2.40 +  /// \brief Gomory-Hu cut tree algorithm
    2.41 +  ///
    2.42 +  /// The Gomory-Hu tree is a tree on the node set of a given graph, but it
    2.43 +  /// may contain edges which are not in the original graph. It has the
    2.44 +  /// property that the minimum capacity edge of the path between two nodes 
    2.45 +  /// in this tree has the same weight as the minimum cut in the graph
    2.46 +  /// between these nodes. Moreover the components obtained by removing
    2.47 +  /// this edge from the tree determine the corresponding minimum cut.
    2.48 +  ///
    2.49 +  /// Therefore once this tree is computed, the minimum cut between any pair
    2.50 +  /// of nodes can easily be obtained.
    2.51 +  /// 
    2.52 +  /// The algorithm calculates \e n-1 distinct minimum cuts (currently with
    2.53 +  /// the \ref Preflow algorithm), therefore the algorithm has
    2.54 +  /// \f$(O(n^3\sqrt{e})\f$ overall time complexity. It calculates a
    2.55 +  /// rooted Gomory-Hu tree, its structure and the weights can be obtained
    2.56 +  /// by \c predNode(), \c predValue() and \c rootDist().
    2.57 +  /// 
    2.58 +  /// The members \c minCutMap() and \c minCutValue() calculate
    2.59 +  /// the minimum cut and the minimum cut value between any two nodes
    2.60 +  /// in the graph. You can also list (iterate on) the nodes and the
    2.61 +  /// edges of the cuts using \c MinCutNodeIt and \c MinCutEdgeIt.
    2.62 +  ///
    2.63 +  /// \tparam GR The type of the undirected graph the algorithm runs on.
    2.64 +  /// \tparam CAP The type of the edge map describing the edge capacities.
    2.65 +  /// It is \ref concepts::Graph::EdgeMap "GR::EdgeMap<int>" by default.
    2.66 +#ifdef DOXYGEN
    2.67 +  template <typename GR,
    2.68 +	    typename CAP>
    2.69 +#else
    2.70 +  template <typename GR,
    2.71 +	    typename CAP = typename GR::template EdgeMap<int> >
    2.72 +#endif
    2.73 +  class GomoryHu {
    2.74 +  public:
    2.75 +
    2.76 +    /// The graph type
    2.77 +    typedef GR Graph;
    2.78 +    /// The type of the edge capacity map
    2.79 +    typedef CAP Capacity;
    2.80 +    /// The value type of capacities
    2.81 +    typedef typename Capacity::Value Value;
    2.82 +    
    2.83 +  private:
    2.84 +
    2.85 +    TEMPLATE_GRAPH_TYPEDEFS(Graph);
    2.86 +
    2.87 +    const Graph& _graph;
    2.88 +    const Capacity& _capacity;
    2.89 +
    2.90 +    Node _root;
    2.91 +    typename Graph::template NodeMap<Node>* _pred;
    2.92 +    typename Graph::template NodeMap<Value>* _weight;
    2.93 +    typename Graph::template NodeMap<int>* _order;
    2.94 +
    2.95 +    void createStructures() {
    2.96 +      if (!_pred) {
    2.97 +	_pred = new typename Graph::template NodeMap<Node>(_graph);
    2.98 +      }
    2.99 +      if (!_weight) {
   2.100 +	_weight = new typename Graph::template NodeMap<Value>(_graph);
   2.101 +      }
   2.102 +      if (!_order) {
   2.103 +	_order = new typename Graph::template NodeMap<int>(_graph);
   2.104 +      }
   2.105 +    }
   2.106 +
   2.107 +    void destroyStructures() {
   2.108 +      if (_pred) {
   2.109 +	delete _pred;
   2.110 +      }
   2.111 +      if (_weight) {
   2.112 +	delete _weight;
   2.113 +      }
   2.114 +      if (_order) {
   2.115 +	delete _order;
   2.116 +      }
   2.117 +    }
   2.118 +  
   2.119 +  public:
   2.120 +
   2.121 +    /// \brief Constructor
   2.122 +    ///
   2.123 +    /// Constructor
   2.124 +    /// \param graph The undirected graph the algorithm runs on.
   2.125 +    /// \param capacity The edge capacity map.
   2.126 +    GomoryHu(const Graph& graph, const Capacity& capacity) 
   2.127 +      : _graph(graph), _capacity(capacity),
   2.128 +	_pred(0), _weight(0), _order(0) 
   2.129 +    {
   2.130 +      checkConcept<concepts::ReadMap<Edge, Value>, Capacity>();
   2.131 +    }
   2.132 +
   2.133 +
   2.134 +    /// \brief Destructor
   2.135 +    ///
   2.136 +    /// Destructor
   2.137 +    ~GomoryHu() {
   2.138 +      destroyStructures();
   2.139 +    }
   2.140 +
   2.141 +  private:
   2.142 +  
   2.143 +    // Initialize the internal data structures
   2.144 +    void init() {
   2.145 +      createStructures();
   2.146 +
   2.147 +      _root = NodeIt(_graph);
   2.148 +      for (NodeIt n(_graph); n != INVALID; ++n) {
   2.149 +	_pred->set(n, _root);
   2.150 +	_order->set(n, -1);
   2.151 +      }
   2.152 +      _pred->set(_root, INVALID);
   2.153 +      _weight->set(_root, std::numeric_limits<Value>::max()); 
   2.154 +    }
   2.155 +
   2.156 +
   2.157 +    // Start the algorithm
   2.158 +    void start() {
   2.159 +      Preflow<Graph, Capacity> fa(_graph, _capacity, _root, INVALID);
   2.160 +
   2.161 +      for (NodeIt n(_graph); n != INVALID; ++n) {
   2.162 +	if (n == _root) continue;
   2.163 +
   2.164 +	Node pn = (*_pred)[n];
   2.165 +	fa.source(n);
   2.166 +	fa.target(pn);
   2.167 +
   2.168 +	fa.runMinCut();
   2.169 +
   2.170 +	_weight->set(n, fa.flowValue());
   2.171 +
   2.172 +	for (NodeIt nn(_graph); nn != INVALID; ++nn) {
   2.173 +	  if (nn != n && fa.minCut(nn) && (*_pred)[nn] == pn) {
   2.174 +	    _pred->set(nn, n);
   2.175 +	  }
   2.176 +	}
   2.177 +	if ((*_pred)[pn] != INVALID && fa.minCut((*_pred)[pn])) {
   2.178 +	  _pred->set(n, (*_pred)[pn]);
   2.179 +	  _pred->set(pn, n);
   2.180 +	  _weight->set(n, (*_weight)[pn]);
   2.181 +	  _weight->set(pn, fa.flowValue());	
   2.182 +	}
   2.183 +      }
   2.184 +
   2.185 +      _order->set(_root, 0);
   2.186 +      int index = 1;
   2.187 +
   2.188 +      for (NodeIt n(_graph); n != INVALID; ++n) {
   2.189 +	std::vector<Node> st;
   2.190 +	Node nn = n;
   2.191 +	while ((*_order)[nn] == -1) {
   2.192 +	  st.push_back(nn);
   2.193 +	  nn = (*_pred)[nn];
   2.194 +	}
   2.195 +	while (!st.empty()) {
   2.196 +	  _order->set(st.back(), index++);
   2.197 +	  st.pop_back();
   2.198 +	}
   2.199 +      }
   2.200 +    }
   2.201 +
   2.202 +  public:
   2.203 +
   2.204 +    ///\name Execution Control
   2.205 + 
   2.206 +    ///@{
   2.207 +
   2.208 +    /// \brief Run the Gomory-Hu algorithm.
   2.209 +    ///
   2.210 +    /// This function runs the Gomory-Hu algorithm.
   2.211 +    void run() {
   2.212 +      init();
   2.213 +      start();
   2.214 +    }
   2.215 +    
   2.216 +    /// @}
   2.217 +
   2.218 +    ///\name Query Functions
   2.219 +    ///The results of the algorithm can be obtained using these
   2.220 +    ///functions.\n
   2.221 +    ///\ref run() "run()" should be called before using them.\n
   2.222 +    ///See also \ref MinCutNodeIt and \ref MinCutEdgeIt.
   2.223 +
   2.224 +    ///@{
   2.225 +
   2.226 +    /// \brief Return the predecessor node in the Gomory-Hu tree.
   2.227 +    ///
   2.228 +    /// This function returns the predecessor node in the Gomory-Hu tree.
   2.229 +    /// If the node is
   2.230 +    /// the root of the Gomory-Hu tree, then it returns \c INVALID.
   2.231 +    Node predNode(const Node& node) {
   2.232 +      return (*_pred)[node];
   2.233 +    }
   2.234 +
   2.235 +    /// \brief Return the distance from the root node in the Gomory-Hu tree.
   2.236 +    ///
   2.237 +    /// This function returns the distance of \c node from the root node
   2.238 +    /// in the Gomory-Hu tree.
   2.239 +    int rootDist(const Node& node) {
   2.240 +      return (*_order)[node];
   2.241 +    }
   2.242 +
   2.243 +    /// \brief Return the weight of the predecessor edge in the
   2.244 +    /// Gomory-Hu tree.
   2.245 +    ///
   2.246 +    /// This function returns the weight of the predecessor edge in the
   2.247 +    /// Gomory-Hu tree.  If the node is the root, the result is undefined.
   2.248 +    Value predValue(const Node& node) {
   2.249 +      return (*_weight)[node];
   2.250 +    }
   2.251 +
   2.252 +    /// \brief Return the minimum cut value between two nodes
   2.253 +    ///
   2.254 +    /// This function returns the minimum cut value between two nodes. The
   2.255 +    /// algorithm finds the nearest common ancestor in the Gomory-Hu
   2.256 +    /// tree and calculates the minimum weight edge on the paths to
   2.257 +    /// the ancestor.
   2.258 +    Value minCutValue(const Node& s, const Node& t) const {
   2.259 +      Node sn = s, tn = t;
   2.260 +      Value value = std::numeric_limits<Value>::max();
   2.261 +      
   2.262 +      while (sn != tn) {
   2.263 +	if ((*_order)[sn] < (*_order)[tn]) {
   2.264 +	  if ((*_weight)[tn] <= value) value = (*_weight)[tn];
   2.265 +	  tn = (*_pred)[tn];
   2.266 +	} else {
   2.267 +	  if ((*_weight)[sn] <= value) value = (*_weight)[sn];
   2.268 +	  sn = (*_pred)[sn];
   2.269 +	}
   2.270 +      }
   2.271 +      return value;
   2.272 +    }
   2.273 +
   2.274 +    /// \brief Return the minimum cut between two nodes
   2.275 +    ///
   2.276 +    /// This function returns the minimum cut between the nodes \c s and \c t
   2.277 +    /// in the \c cutMap parameter by setting the nodes in the component of
   2.278 +    /// \c s to \c true and the other nodes to \c false.
   2.279 +    ///
   2.280 +    /// For higher level interfaces, see MinCutNodeIt and MinCutEdgeIt.
   2.281 +    template <typename CutMap>
   2.282 +    Value minCutMap(const Node& s, ///< The base node.
   2.283 +                    const Node& t,
   2.284 +                    ///< The node you want to separate from node \c s.
   2.285 +                    CutMap& cutMap
   2.286 +                    ///< The cut will be returned in this map.
   2.287 +                    /// It must be a \c bool (or convertible) 
   2.288 +                    /// \ref concepts::ReadWriteMap "ReadWriteMap"
   2.289 +                    /// on the graph nodes.
   2.290 +                    ) const {
   2.291 +      Node sn = s, tn = t;
   2.292 +      bool s_root=false;
   2.293 +      Node rn = INVALID;
   2.294 +      Value value = std::numeric_limits<Value>::max();
   2.295 +      
   2.296 +      while (sn != tn) {
   2.297 +	if ((*_order)[sn] < (*_order)[tn]) {
   2.298 +	  if ((*_weight)[tn] <= value) {
   2.299 +	    rn = tn;
   2.300 +            s_root = false;
   2.301 +	    value = (*_weight)[tn];
   2.302 +	  }
   2.303 +	  tn = (*_pred)[tn];
   2.304 +	} else {
   2.305 +	  if ((*_weight)[sn] <= value) {
   2.306 +	    rn = sn;
   2.307 +            s_root = true;
   2.308 +	    value = (*_weight)[sn];
   2.309 +	  }
   2.310 +	  sn = (*_pred)[sn];
   2.311 +	}
   2.312 +      }
   2.313 +
   2.314 +      typename Graph::template NodeMap<bool> reached(_graph, false);
   2.315 +      reached.set(_root, true);
   2.316 +      cutMap.set(_root, !s_root);
   2.317 +      reached.set(rn, true);
   2.318 +      cutMap.set(rn, s_root);
   2.319 +
   2.320 +      std::vector<Node> st;
   2.321 +      for (NodeIt n(_graph); n != INVALID; ++n) {
   2.322 +	st.clear();
   2.323 +        Node nn = n;
   2.324 +	while (!reached[nn]) {
   2.325 +	  st.push_back(nn);
   2.326 +	  nn = (*_pred)[nn];
   2.327 +	}
   2.328 +	while (!st.empty()) {
   2.329 +	  cutMap.set(st.back(), cutMap[nn]);
   2.330 +	  st.pop_back();
   2.331 +	}
   2.332 +      }
   2.333 +      
   2.334 +      return value;
   2.335 +    }
   2.336 +
   2.337 +    ///@}
   2.338 +
   2.339 +    friend class MinCutNodeIt;
   2.340 +
   2.341 +    /// Iterate on the nodes of a minimum cut
   2.342 +    
   2.343 +    /// This iterator class lists the nodes of a minimum cut found by
   2.344 +    /// GomoryHu. Before using it, you must allocate a GomoryHu class,
   2.345 +    /// and call its \ref GomoryHu::run() "run()" method.
   2.346 +    ///
   2.347 +    /// This example counts the nodes in the minimum cut separating \c s from
   2.348 +    /// \c t.
   2.349 +    /// \code
   2.350 +    /// GomoruHu<Graph> gom(g, capacities);
   2.351 +    /// gom.run();
   2.352 +    /// int cnt=0;
   2.353 +    /// for(GomoruHu<Graph>::MinCutNodeIt n(gom,s,t); n!=INVALID; ++n) ++cnt;
   2.354 +    /// \endcode
   2.355 +    class MinCutNodeIt
   2.356 +    {
   2.357 +      bool _side;
   2.358 +      typename Graph::NodeIt _node_it;
   2.359 +      typename Graph::template NodeMap<bool> _cut;
   2.360 +    public:
   2.361 +      /// Constructor
   2.362 +
   2.363 +      /// Constructor.
   2.364 +      ///
   2.365 +      MinCutNodeIt(GomoryHu const &gomory,
   2.366 +                   ///< The GomoryHu class. You must call its
   2.367 +                   ///  run() method
   2.368 +                   ///  before initializing this iterator.
   2.369 +                   const Node& s, ///< The base node.
   2.370 +                   const Node& t,
   2.371 +                   ///< The node you want to separate from node \c s.
   2.372 +                   bool side=true
   2.373 +                   ///< If it is \c true (default) then the iterator lists
   2.374 +                   ///  the nodes of the component containing \c s,
   2.375 +                   ///  otherwise it lists the other component.
   2.376 +                   /// \note As the minimum cut is not always unique,
   2.377 +                   /// \code
   2.378 +                   /// MinCutNodeIt(gomory, s, t, true);
   2.379 +                   /// \endcode
   2.380 +                   /// and
   2.381 +                   /// \code
   2.382 +                   /// MinCutNodeIt(gomory, t, s, false);
   2.383 +                   /// \endcode
   2.384 +                   /// does not necessarily give the same set of nodes.
   2.385 +                   /// However it is ensured that
   2.386 +                   /// \code
   2.387 +                   /// MinCutNodeIt(gomory, s, t, true);
   2.388 +                   /// \endcode
   2.389 +                   /// and
   2.390 +                   /// \code
   2.391 +                   /// MinCutNodeIt(gomory, s, t, false);
   2.392 +                   /// \endcode
   2.393 +                   /// together list each node exactly once.
   2.394 +                   )
   2.395 +        : _side(side), _cut(gomory._graph)
   2.396 +      {
   2.397 +        gomory.minCutMap(s,t,_cut);
   2.398 +        for(_node_it=typename Graph::NodeIt(gomory._graph);
   2.399 +            _node_it!=INVALID && _cut[_node_it]!=_side;
   2.400 +            ++_node_it) {}
   2.401 +      }
   2.402 +      /// Conversion to \c Node
   2.403 +
   2.404 +      /// Conversion to \c Node.
   2.405 +      ///
   2.406 +      operator typename Graph::Node() const
   2.407 +      {
   2.408 +        return _node_it;
   2.409 +      }
   2.410 +      bool operator==(Invalid) { return _node_it==INVALID; }
   2.411 +      bool operator!=(Invalid) { return _node_it!=INVALID; }
   2.412 +      /// Next node
   2.413 +
   2.414 +      /// Next node.
   2.415 +      ///
   2.416 +      MinCutNodeIt &operator++()
   2.417 +      {
   2.418 +        for(++_node_it;_node_it!=INVALID&&_cut[_node_it]!=_side;++_node_it) {}
   2.419 +        return *this;
   2.420 +      }
   2.421 +      /// Postfix incrementation
   2.422 +
   2.423 +      /// Postfix incrementation.
   2.424 +      ///
   2.425 +      /// \warning This incrementation
   2.426 +      /// returns a \c Node, not a \c MinCutNodeIt, as one may
   2.427 +      /// expect.
   2.428 +      typename Graph::Node operator++(int)
   2.429 +      {
   2.430 +        typename Graph::Node n=*this;
   2.431 +        ++(*this);
   2.432 +        return n;
   2.433 +      }
   2.434 +    };
   2.435 +    
   2.436 +    friend class MinCutEdgeIt;
   2.437 +    
   2.438 +    /// Iterate on the edges of a minimum cut
   2.439 +    
   2.440 +    /// This iterator class lists the edges of a minimum cut found by
   2.441 +    /// GomoryHu. Before using it, you must allocate a GomoryHu class,
   2.442 +    /// and call its \ref GomoryHu::run() "run()" method.
   2.443 +    ///
   2.444 +    /// This example computes the value of the minimum cut separating \c s from
   2.445 +    /// \c t.
   2.446 +    /// \code
   2.447 +    /// GomoruHu<Graph> gom(g, capacities);
   2.448 +    /// gom.run();
   2.449 +    /// int value=0;
   2.450 +    /// for(GomoruHu<Graph>::MinCutEdgeIt e(gom,s,t); e!=INVALID; ++e)
   2.451 +    ///   value+=capacities[e];
   2.452 +    /// \endcode
   2.453 +    /// the result will be the same as it is returned by
   2.454 +    /// \ref GomoryHu::minCutValue() "gom.minCutValue(s,t)"
   2.455 +    class MinCutEdgeIt
   2.456 +    {
   2.457 +      bool _side;
   2.458 +      const Graph &_graph;
   2.459 +      typename Graph::NodeIt _node_it;
   2.460 +      typename Graph::OutArcIt _arc_it;
   2.461 +      typename Graph::template NodeMap<bool> _cut;
   2.462 +      void step()
   2.463 +      {
   2.464 +        ++_arc_it;
   2.465 +        while(_node_it!=INVALID && _arc_it==INVALID)
   2.466 +          {
   2.467 +            for(++_node_it;_node_it!=INVALID&&!_cut[_node_it];++_node_it) {}
   2.468 +            if(_node_it!=INVALID)
   2.469 +              _arc_it=typename Graph::OutArcIt(_graph,_node_it);
   2.470 +          }
   2.471 +      }
   2.472 +      
   2.473 +    public:
   2.474 +      MinCutEdgeIt(GomoryHu const &gomory,
   2.475 +                   ///< The GomoryHu class. You must call its
   2.476 +                   ///  run() method
   2.477 +                   ///  before initializing this iterator.
   2.478 +                   const Node& s,  ///< The base node.
   2.479 +                   const Node& t,
   2.480 +                   ///< The node you want to separate from node \c s.
   2.481 +                   bool side=true
   2.482 +                   ///< If it is \c true (default) then the listed arcs
   2.483 +                   ///  will be oriented from the
   2.484 +                   ///  the nodes of the component containing \c s,
   2.485 +                   ///  otherwise they will be oriented in the opposite
   2.486 +                   ///  direction.
   2.487 +                   )
   2.488 +        : _graph(gomory._graph), _cut(_graph)
   2.489 +      {
   2.490 +        gomory.minCutMap(s,t,_cut);
   2.491 +        if(!side)
   2.492 +          for(typename Graph::NodeIt n(_graph);n!=INVALID;++n)
   2.493 +            _cut[n]=!_cut[n];
   2.494 +
   2.495 +        for(_node_it=typename Graph::NodeIt(_graph);
   2.496 +            _node_it!=INVALID && !_cut[_node_it];
   2.497 +            ++_node_it) {}
   2.498 +        _arc_it = _node_it!=INVALID ?
   2.499 +          typename Graph::OutArcIt(_graph,_node_it) : INVALID;
   2.500 +        while(_node_it!=INVALID && _arc_it == INVALID)
   2.501 +          {
   2.502 +            for(++_node_it; _node_it!=INVALID&&!_cut[_node_it]; ++_node_it) {}
   2.503 +            if(_node_it!=INVALID)
   2.504 +              _arc_it= typename Graph::OutArcIt(_graph,_node_it);
   2.505 +          }
   2.506 +        while(_arc_it!=INVALID && _cut[_graph.target(_arc_it)]) step();
   2.507 +      }
   2.508 +      /// Conversion to \c Arc
   2.509 +
   2.510 +      /// Conversion to \c Arc.
   2.511 +      ///
   2.512 +      operator typename Graph::Arc() const
   2.513 +      {
   2.514 +        return _arc_it;
   2.515 +      }
   2.516 +      /// Conversion to \c Edge
   2.517 +
   2.518 +      /// Conversion to \c Edge.
   2.519 +      ///
   2.520 +      operator typename Graph::Edge() const
   2.521 +      {
   2.522 +        return _arc_it;
   2.523 +      }
   2.524 +      bool operator==(Invalid) { return _node_it==INVALID; }
   2.525 +      bool operator!=(Invalid) { return _node_it!=INVALID; }
   2.526 +      /// Next edge
   2.527 +
   2.528 +      /// Next edge.
   2.529 +      ///
   2.530 +      MinCutEdgeIt &operator++()
   2.531 +      {
   2.532 +        step();
   2.533 +        while(_arc_it!=INVALID && _cut[_graph.target(_arc_it)]) step();
   2.534 +        return *this;
   2.535 +      }
   2.536 +      /// Postfix incrementation
   2.537 +      
   2.538 +      /// Postfix incrementation.
   2.539 +      ///
   2.540 +      /// \warning This incrementation
   2.541 +      /// returns an \c Arc, not a \c MinCutEdgeIt, as one may expect.
   2.542 +      typename Graph::Arc operator++(int)
   2.543 +      {
   2.544 +        typename Graph::Arc e=*this;
   2.545 +        ++(*this);
   2.546 +        return e;
   2.547 +      }
   2.548 +    };
   2.549 +
   2.550 +  };
   2.551 +
   2.552 +}
   2.553 +
   2.554 +#endif
     3.1 --- a/test/CMakeLists.txt	Wed Mar 04 13:43:05 2009 +0000
     3.2 +++ b/test/CMakeLists.txt	Wed Mar 04 14:09:45 2009 +0000
     3.3 @@ -21,6 +21,7 @@
     3.4    edge_set_test
     3.5    error_test
     3.6    euler_test
     3.7 +  gomory_hu_test
     3.8    graph_copy_test
     3.9    graph_test
    3.10    graph_utils_test
     4.1 --- a/test/Makefile.am	Wed Mar 04 13:43:05 2009 +0000
     4.2 +++ b/test/Makefile.am	Wed Mar 04 14:09:45 2009 +0000
     4.3 @@ -17,6 +17,7 @@
     4.4  	test/edge_set_test \
     4.5  	test/error_test \
     4.6  	test/euler_test \
     4.7 +	test/gomory_hu_test \
     4.8  	test/graph_copy_test \
     4.9  	test/graph_test \
    4.10  	test/graph_utils_test \
    4.11 @@ -57,6 +58,7 @@
    4.12  test_edge_set_test_SOURCES = test/edge_set_test.cc
    4.13  test_error_test_SOURCES = test/error_test.cc
    4.14  test_euler_test_SOURCES = test/euler_test.cc
    4.15 +test_gomory_hu_test_SOURCES = test/gomory_hu_test.cc
    4.16  test_graph_copy_test_SOURCES = test/graph_copy_test.cc
    4.17  test_graph_test_SOURCES = test/graph_test.cc
    4.18  test_graph_utils_test_SOURCES = test/graph_utils_test.cc
     5.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     5.2 +++ b/test/gomory_hu_test.cc	Wed Mar 04 14:09:45 2009 +0000
     5.3 @@ -0,0 +1,92 @@
     5.4 +#include <iostream>
     5.5 +
     5.6 +#include "test_tools.h"
     5.7 +#include <lemon/smart_graph.h>
     5.8 +#include <lemon/lgf_reader.h>
     5.9 +#include <lemon/gomory_hu.h>
    5.10 +#include <cstdlib>
    5.11 +
    5.12 +using namespace std;
    5.13 +using namespace lemon;
    5.14 +
    5.15 +typedef SmartGraph Graph;
    5.16 +
    5.17 +char test_lgf[] =
    5.18 +  "@nodes\n"
    5.19 +  "label\n"
    5.20 +  "0\n"
    5.21 +  "1\n"
    5.22 +  "2\n"
    5.23 +  "3\n"
    5.24 +  "4\n"
    5.25 +  "@arcs\n"
    5.26 +  "     label capacity\n"
    5.27 +  "0 1  0     1\n"
    5.28 +  "1 2  1     1\n"
    5.29 +  "2 3  2     1\n"
    5.30 +  "0 3  4     5\n"
    5.31 +  "0 3  5     10\n"
    5.32 +  "0 3  6     7\n"
    5.33 +  "4 2  7     1\n"
    5.34 +  "@attributes\n"
    5.35 +  "source 0\n"
    5.36 +  "target 3\n";
    5.37 +  
    5.38 +GRAPH_TYPEDEFS(Graph);
    5.39 +typedef Graph::EdgeMap<int> IntEdgeMap;
    5.40 +typedef Graph::NodeMap<bool> BoolNodeMap;
    5.41 +
    5.42 +int cutValue(const Graph& graph, const BoolNodeMap& cut,
    5.43 +	     const IntEdgeMap& capacity) {
    5.44 +
    5.45 +  int sum = 0;
    5.46 +  for (EdgeIt e(graph); e != INVALID; ++e) {
    5.47 +    Node s = graph.u(e);
    5.48 +    Node t = graph.v(e);
    5.49 +
    5.50 +    if (cut[s] != cut[t]) {
    5.51 +      sum += capacity[e];
    5.52 +    }
    5.53 +  }
    5.54 +  return sum;
    5.55 +}
    5.56 +
    5.57 +
    5.58 +int main() {
    5.59 +  Graph graph;
    5.60 +  IntEdgeMap capacity(graph);
    5.61 +
    5.62 +  std::istringstream input(test_lgf);
    5.63 +  GraphReader<Graph>(graph, input).
    5.64 +    edgeMap("capacity", capacity).run();
    5.65 +
    5.66 +  GomoryHu<Graph> ght(graph, capacity);
    5.67 +  ght.run();
    5.68 +
    5.69 +  for (NodeIt u(graph); u != INVALID; ++u) {
    5.70 +    for (NodeIt v(graph); v != u; ++v) {
    5.71 +      Preflow<Graph, IntEdgeMap> pf(graph, capacity, u, v);
    5.72 +      pf.runMinCut();
    5.73 +      BoolNodeMap cm(graph);
    5.74 +      ght.minCutMap(u, v, cm);
    5.75 +      check(pf.flowValue() == ght.minCutValue(u, v), "Wrong cut 1");
    5.76 +      check(cm[u] != cm[v], "Wrong cut 3");
    5.77 +      check(pf.flowValue() == cutValue(graph, cm, capacity), "Wrong cut 2");
    5.78 +
    5.79 +      int sum=0;
    5.80 +      for(GomoryHu<Graph>::MinCutEdgeIt a(ght, u, v);a!=INVALID;++a)
    5.81 +        sum+=capacity[a]; 
    5.82 +      check(sum == ght.minCutValue(u, v), "Problem with MinCutEdgeIt");
    5.83 +
    5.84 +      sum=0;
    5.85 +      for(GomoryHu<Graph>::MinCutNodeIt n(ght, u, v,true);n!=INVALID;++n)
    5.86 +        sum++;
    5.87 +      for(GomoryHu<Graph>::MinCutNodeIt n(ght, u, v,false);n!=INVALID;++n)
    5.88 +        sum++;
    5.89 +      check(sum == countNodes(graph), "Problem with MinCutNodeIt");
    5.90 +      
    5.91 +    }
    5.92 +  }
    5.93 +  
    5.94 +  return 0;
    5.95 +}