src/work/marci/augmenting_flow.h
author alpar
Wed, 29 Sep 2004 15:30:04 +0000
changeset 921 818510fa3d99
parent 888 cc3590763f7f
child 944 4f064aff855e
permissions -rw-r--r--
hugo -> lemon
     1 // -*- C++ -*-
     2 #ifndef LEMON_AUGMENTING_FLOW_H
     3 #define LEMON_AUGMENTING_FLOW_H
     4 
     5 #include <vector>
     6 #include <iostream>
     7 
     8 #include <lemon/graph_wrapper.h>
     9 #include <bfs_dfs.h>
    10 #include <lemon/invalid.h>
    11 #include <lemon/maps.h>
    12 #include <lemon/tight_edge_filter_map.h>
    13 
    14 /// \file
    15 /// \brief Maximum flow algorithms.
    16 /// \ingroup galgs
    17 
    18 namespace lemon {
    19 
    20   /// \addtogroup galgs
    21   /// @{                                                                                                                                        
    22   /// Class for augmenting path flow algorithms.
    23 
    24   /// This class provides various algorithms for finding a flow of
    25   /// maximum value in a directed graph. The \e source node, the \e
    26   /// target node, the \e capacity of the edges and the \e starting \e
    27   /// flow value of the edges should be passed to the algorithm through the
    28   /// constructor. 
    29 //   /// It is possible to change these quantities using the
    30 //   /// functions \ref resetSource, \ref resetTarget, \ref resetCap and
    31 //   /// \ref resetFlow. Before any subsequent runs of any algorithm of
    32 //   /// the class \ref resetFlow should be called. 
    33 
    34   /// After running an algorithm of the class, the actual flow value 
    35   /// can be obtained by calling \ref flowValue(). The minimum
    36   /// value cut can be written into a \c node map of \c bools by
    37   /// calling \ref minCut. (\ref minMinCut and \ref maxMinCut writes
    38   /// the inclusionwise minimum and maximum of the minimum value
    39   /// cuts, resp.)                                                                                                                               
    40   ///\param Graph The directed graph type the algorithm runs on.
    41   ///\param Num The number type of the capacities and the flow values.
    42   ///\param CapMap The capacity map type.
    43   ///\param FlowMap The flow map type.                                                                                                           
    44   ///\author Marton Makai
    45   template <typename Graph, typename Num,
    46 	    typename CapMap=typename Graph::template EdgeMap<Num>,
    47             typename FlowMap=typename Graph::template EdgeMap<Num> >
    48   class AugmentingFlow {
    49   protected:
    50     typedef typename Graph::Node Node;
    51     typedef typename Graph::NodeIt NodeIt;
    52     typedef typename Graph::EdgeIt EdgeIt;
    53     typedef typename Graph::OutEdgeIt OutEdgeIt;
    54     typedef typename Graph::InEdgeIt InEdgeIt;
    55 
    56     const Graph* g;
    57     Node s;
    58     Node t;
    59     const CapMap* capacity;
    60     FlowMap* flow;
    61 //    int n;      //the number of nodes of G
    62     typedef ResGraphWrapper<const Graph, Num, CapMap, FlowMap> ResGW;   
    63     //typedef ExpResGraphWrapper<const Graph, Num, CapMap, FlowMap> ResGW;
    64     typedef typename ResGW::OutEdgeIt ResGWOutEdgeIt;
    65     typedef typename ResGW::Edge ResGWEdge;
    66     //typedef typename ResGW::template NodeMap<bool> ReachedMap;
    67     typedef typename Graph::template NodeMap<int> ReachedMap;
    68 
    69     //level works as a bool map in augmenting path algorithms and is
    70     //used by bfs for storing reached information.  In preflow, it
    71     //shows the levels of nodes.     
    72     ReachedMap level;
    73 
    74   public:
    75     ///Indicates the property of the starting flow.
    76 
    77     ///Indicates the property of the starting flow. The meanings are as follows:
    78     ///- \c ZERO_FLOW: constant zero flow
    79     ///- \c GEN_FLOW: any flow, i.e. the sum of the in-flows equals to
    80     ///the sum of the out-flows in every node except the \e source and
    81     ///the \e target.
    82     ///- \c PRE_FLOW: any preflow, i.e. the sum of the in-flows is at 
    83     ///least the sum of the out-flows in every node except the \e source.
    84     ///- \c NO_FLOW: indicates an unspecified edge map. \ref flow will be 
    85     ///set to the constant zero flow in the beginning of the algorithm in this case.
    86     enum FlowEnum{
    87       ZERO_FLOW,
    88       GEN_FLOW,
    89       PRE_FLOW,
    90       NO_FLOW
    91     };
    92 
    93     enum StatusEnum {
    94       AFTER_NOTHING,
    95       AFTER_AUGMENTING,
    96       AFTER_FAST_AUGMENTING, 
    97       AFTER_PRE_FLOW_PHASE_1,      
    98       AFTER_PRE_FLOW_PHASE_2
    99     };
   100 
   101     /// Don not needle this flag only if necessary.
   102     StatusEnum status;
   103     int number_of_augmentations;
   104 
   105 
   106     template<typename IntMap>
   107     class TrickyReachedMap {
   108     protected:
   109       IntMap* map;
   110       int* number_of_augmentations;
   111     public:
   112       TrickyReachedMap(IntMap& _map, int& _number_of_augmentations) : 
   113 	map(&_map), number_of_augmentations(&_number_of_augmentations) { }
   114       void set(const Node& n, bool b) {
   115 	if (b)
   116 	  map->set(n, *number_of_augmentations);
   117 	else 
   118 	  map->set(n, *number_of_augmentations-1);
   119       }
   120       bool operator[](const Node& n) const { 
   121 	return (*map)[n]==*number_of_augmentations; 
   122       }
   123     };
   124     
   125     AugmentingFlow(const Graph& _G, Node _s, Node _t, const CapMap& _capacity,
   126 		   FlowMap& _flow) :
   127       g(&_G), s(_s), t(_t), capacity(&_capacity),
   128       flow(&_flow), //n(_G.nodeNum()), 
   129       level(_G), //excess(_G,0), 
   130       status(AFTER_NOTHING), number_of_augmentations(0) { }
   131 
   132     /// Starting from a flow, this method searches for an augmenting path
   133     /// according to the Edmonds-Karp algorithm
   134     /// and augments the flow on if any.
   135     /// The return value shows if the augmentation was succesful.
   136     bool augmentOnShortestPath();
   137     bool augmentOnShortestPath2();
   138 
   139     /// Starting from a flow, this method searches for an augmenting blocking
   140     /// flow according to Dinits' algorithm and augments the flow on if any.
   141     /// The blocking flow is computed in a physically constructed
   142     /// residual graph of type \c Mutablegraph.
   143     /// The return value show sif the augmentation was succesful.
   144     template<typename MutableGraph> bool augmentOnBlockingFlow();
   145 
   146     /// The same as \c augmentOnBlockingFlow<MutableGraph> but the
   147     /// residual graph is not constructed physically.
   148     /// The return value shows if the augmentation was succesful.
   149     bool augmentOnBlockingFlow2();
   150 
   151     template<typename _CutMap>
   152     void actMinCut(_CutMap& M) const {
   153       NodeIt v;
   154       switch (status) {
   155 	case AFTER_PRE_FLOW_PHASE_1:
   156 //	std::cout << "AFTER_PRE_FLOW_PHASE_1" << std::endl;
   157 // 	for(g->first(v); g->valid(v); g->next(v)) {
   158 // 	  if (level[v] < n) {
   159 // 	    M.set(v, false);
   160 // 	  } else {
   161 // 	    M.set(v, true);
   162 // 	  }
   163 // 	}
   164 	break;
   165       case AFTER_PRE_FLOW_PHASE_2:
   166 //	std::cout << "AFTER_PRE_FLOW_PHASE_2" << std::endl;
   167 	break;
   168       case AFTER_NOTHING:
   169 //	std::cout << "AFTER_NOTHING" << std::endl;
   170 	minMinCut(M);
   171 	break;
   172       case AFTER_AUGMENTING:
   173 //	std::cout << "AFTER_AUGMENTING" << std::endl;
   174 	for(g->first(v); v!=INVALID; ++v) {
   175 	  if (level[v]) {
   176 	    M.set(v, true);
   177 	  } else {
   178 	    M.set(v, false);
   179 	  }
   180 	}
   181 	break;
   182       case AFTER_FAST_AUGMENTING:
   183 //	std::cout << "AFTER_FAST_AUGMENTING" << std::endl;
   184 	for(g->first(v); v!=INVALID; ++v) {
   185 	  if (level[v]==number_of_augmentations) {
   186 	    M.set(v, true);
   187 	  } else {
   188 	    M.set(v, false);
   189 	  }
   190 	}
   191 	break;
   192       }
   193     }
   194 
   195     template<typename _CutMap>
   196     void minMinCut(_CutMap& M) const {
   197       std::queue<Node> queue;
   198 
   199       M.set(s,true);
   200       queue.push(s);
   201 
   202       while (!queue.empty()) {
   203         Node w=queue.front();
   204 	queue.pop();
   205 
   206 	OutEdgeIt e;
   207 	for(g->first(e,w) ; e!=INVALID; ++e) {
   208 	  Node v=g->head(e);
   209 	  if (!M[v] && (*flow)[e] < (*capacity)[e] ) {
   210 	    queue.push(v);
   211 	    M.set(v, true);
   212 	  }
   213 	}
   214 
   215 	InEdgeIt f;
   216 	for(g->first(f,w) ; f!=INVALID; ++f) {
   217 	  Node v=g->tail(f);
   218 	  if (!M[v] && (*flow)[f] > 0 ) {
   219 	    queue.push(v);
   220 	    M.set(v, true);
   221 	  }
   222 	}
   223       }
   224     }
   225 
   226     template<typename _CutMap>
   227     void minMinCut2(_CutMap& M) const {
   228       ResGW res_graph(*g, *capacity, *flow);
   229       BfsIterator<ResGW, _CutMap> bfs(res_graph, M);
   230       bfs.pushAndSetReached(s);
   231       while (!bfs.finished()) ++bfs;
   232     }
   233 
   234     Num flowValue() const {
   235       Num a=0;
   236       for (InEdgeIt e(*g, t); e!=INVALID; ++e) a+=(*flow)[e];
   237       for (OutEdgeIt e(*g, t); e!=INVALID; ++e) a-=(*flow)[e];
   238       return a;
   239       //marci figyu: excess[t] epp ezt adja preflow 1. fazisa utan   
   240     }
   241 
   242   };
   243 
   244 
   245 
   246   template <typename Graph, typename Num, typename CapMap, typename FlowMap>
   247   bool AugmentingFlow<Graph, Num, CapMap, FlowMap>::augmentOnShortestPath()
   248   {
   249     ResGW res_graph(*g, *capacity, *flow);
   250     typename ResGW::ResCap res_cap(res_graph);
   251 
   252     bool _augment=false;
   253 
   254     //ReachedMap level(res_graph);
   255     for (typename Graph::NodeIt n(*g); n!=INVALID; ++n) level.set(n, 0);
   256     BfsIterator<ResGW, ReachedMap> bfs(res_graph, level);
   257     bfs.pushAndSetReached(s);
   258 
   259     typename ResGW::template NodeMap<ResGWEdge> pred(res_graph);
   260     pred.set(s, INVALID);
   261 
   262     typename ResGW::template NodeMap<Num> free(res_graph);
   263 
   264     //searching for augmenting path
   265     while ( !bfs.finished() ) {
   266       ResGWEdge e=bfs;
   267       if (e!=INVALID && bfs.isBNodeNewlyReached()) {
   268 	Node v=res_graph.tail(e);
   269 	Node w=res_graph.head(e);
   270 	pred.set(w, e);
   271 	if (pred[v]!=INVALID) {
   272 	  free.set(w, std::min(free[v], res_cap[e]));
   273 	} else {
   274 	  free.set(w, res_cap[e]);
   275 	}
   276 	if (res_graph.head(e)==t) { _augment=true; break; }
   277       }
   278 
   279       ++bfs;
   280     } //end of searching augmenting path
   281 
   282     if (_augment) {
   283       Node n=t;
   284       Num augment_value=free[t];
   285       while (pred[n]!=INVALID) {
   286 	ResGWEdge e=pred[n];
   287 	res_graph.augment(e, augment_value);
   288 	n=res_graph.tail(e);
   289       }
   290     }
   291 
   292     status=AFTER_AUGMENTING;
   293     return _augment;
   294   }
   295 
   296   template <typename Graph, typename Num, typename CapMap, typename FlowMap>
   297   bool AugmentingFlow<Graph, Num, CapMap, FlowMap>::augmentOnShortestPath2()
   298   {
   299     ResGW res_graph(*g, *capacity, *flow);
   300     typename ResGW::ResCap res_cap(res_graph);
   301 
   302     bool _augment=false;
   303 
   304     if (status!=AFTER_FAST_AUGMENTING) {
   305       for (typename Graph::NodeIt n(*g); n!=INVALID; ++n) level.set(n, 0); 
   306       number_of_augmentations=1;
   307     } else {
   308       ++number_of_augmentations;
   309     }
   310     TrickyReachedMap<ReachedMap> 
   311       tricky_reached_map(level, number_of_augmentations);
   312     //ReachedMap level(res_graph);
   313 //    FOR_EACH_LOC(typename Graph::NodeIt, e, *g) level.set(e, 0);
   314     BfsIterator<ResGW, TrickyReachedMap<ReachedMap> > 
   315       bfs(res_graph, tricky_reached_map);
   316     bfs.pushAndSetReached(s);
   317 
   318     typename ResGW::template NodeMap<ResGWEdge> pred(res_graph);
   319     pred.set(s, INVALID);
   320 
   321     typename ResGW::template NodeMap<Num> free(res_graph);
   322 
   323     //searching for augmenting path
   324     while ( !bfs.finished() ) {
   325       ResGWEdge e=bfs;
   326       if (e!=INVALID && bfs.isBNodeNewlyReached()) {
   327 	Node v=res_graph.tail(e);
   328 	Node w=res_graph.head(e);
   329 	pred.set(w, e);
   330 	if (pred[v]!=INVALID) {
   331 	  free.set(w, std::min(free[v], res_cap[e]));
   332 	} else {
   333 	  free.set(w, res_cap[e]);
   334 	}
   335 	if (res_graph.head(e)==t) { _augment=true; break; }
   336       }
   337 
   338       ++bfs;
   339     } //end of searching augmenting path
   340 
   341     if (_augment) {
   342       Node n=t;
   343       Num augment_value=free[t];
   344       while (pred[n]!=INVALID) {
   345 	ResGWEdge e=pred[n];
   346 	res_graph.augment(e, augment_value);
   347 	n=res_graph.tail(e);
   348       }
   349     }
   350 
   351     status=AFTER_FAST_AUGMENTING;
   352     return _augment;
   353   }
   354 
   355 
   356   template <typename Graph, typename Num, typename CapMap, typename FlowMap>
   357   template<typename MutableGraph>
   358   bool AugmentingFlow<Graph, Num, CapMap, FlowMap>::augmentOnBlockingFlow()
   359   {
   360     typedef MutableGraph MG;
   361     bool _augment=false;
   362 
   363     ResGW res_graph(*g, *capacity, *flow);
   364     typename ResGW::ResCap res_cap(res_graph);
   365 
   366     //bfs for distances on the residual graph
   367     //ReachedMap level(res_graph);
   368     for (typename Graph::NodeIt n(*g); n!=INVALID; ++n) level.set(n, 0);
   369     BfsIterator<ResGW, ReachedMap> bfs(res_graph, level);
   370     bfs.pushAndSetReached(s);
   371     typename ResGW::template NodeMap<int>
   372       dist(res_graph); //filled up with 0's
   373 
   374     //F will contain the physical copy of the residual graph
   375     //with the set of edges which are on shortest paths
   376     MG F;
   377     typename ResGW::template NodeMap<typename MG::Node>
   378       res_graph_to_F(res_graph);
   379     {
   380       typename ResGW::NodeIt n;
   381       for(res_graph.first(n); n!=INVALID; ++n) 
   382 	res_graph_to_F.set(n, F.addNode());
   383     }
   384 
   385     typename MG::Node sF=res_graph_to_F[s];
   386     typename MG::Node tF=res_graph_to_F[t];
   387     typename MG::template EdgeMap<ResGWEdge> original_edge(F);
   388     typename MG::template EdgeMap<Num> residual_capacity(F);
   389 
   390     while ( !bfs.finished() ) {
   391       ResGWEdge e=bfs;
   392       if (e!=INVALID) {
   393 	if (bfs.isBNodeNewlyReached()) {
   394 	  dist.set(res_graph.head(e), dist[res_graph.tail(e)]+1);
   395 	  typename MG::Edge f=F.addEdge(res_graph_to_F[res_graph.tail(e)],
   396 					res_graph_to_F[res_graph.head(e)]);
   397 	  //original_edge.update();
   398 	  original_edge.set(f, e);
   399 	  //residual_capacity.update();
   400 	  residual_capacity.set(f, res_cap[e]);
   401 	} else {
   402 	  if (dist[res_graph.head(e)]==(dist[res_graph.tail(e)]+1)) {
   403 	    typename MG::Edge f=F.addEdge(res_graph_to_F[res_graph.tail(e)],
   404 					  res_graph_to_F[res_graph.head(e)]);
   405 	    //original_edge.update();
   406 	    original_edge.set(f, e);
   407 	    //residual_capacity.update();
   408 	    residual_capacity.set(f, res_cap[e]);
   409 	  }
   410 	}
   411       }
   412       ++bfs;
   413     } //computing distances from s in the residual graph
   414 
   415     bool __augment=true;
   416 
   417     while (__augment) {
   418       __augment=false;
   419       //computing blocking flow with dfs
   420       DfsIterator< MG, typename MG::template NodeMap<bool> > dfs(F);
   421       typename MG::template NodeMap<typename MG::Edge> pred(F);
   422       pred.set(sF, INVALID);
   423       //invalid iterators for sources
   424 
   425       typename MG::template NodeMap<Num> free(F);
   426 
   427       dfs.pushAndSetReached(sF);
   428       while (!dfs.finished()) {
   429 	++dfs;
   430 	if (typename MG::Edge(dfs)!=INVALID) {
   431 	  if (dfs.isBNodeNewlyReached()) {
   432 	    typename MG::Node v=F.tail(dfs);
   433 	    typename MG::Node w=F.head(dfs);
   434 	    pred.set(w, dfs);
   435 	    if (pred[v]!=INVALID) {
   436 	      free.set(w, std::min(free[v], residual_capacity[dfs]));
   437 	    } else {
   438 	      free.set(w, residual_capacity[dfs]);
   439 	    }
   440 	    if (w==tF) {
   441 	      __augment=true;
   442 	      _augment=true;
   443 	      break;
   444 	    }
   445 
   446 	  } else {
   447 	    F.erase(typename MG::Edge(dfs));
   448 	  }
   449 	}
   450       }
   451 
   452       if (__augment) {
   453 	typename MG::Node n=tF;
   454 	Num augment_value=free[tF];
   455 	while (pred[n]!=INVALID) {
   456 	  typename MG::Edge e=pred[n];
   457 	  res_graph.augment(original_edge[e], augment_value);
   458 	  n=F.tail(e);
   459 	  if (residual_capacity[e]==augment_value)
   460 	    F.erase(e);
   461 	  else
   462 	    residual_capacity.set(e, residual_capacity[e]-augment_value);
   463 	}
   464       }
   465 
   466     }
   467 
   468     status=AFTER_AUGMENTING;
   469     return _augment;
   470   }
   471 
   472   /// Blocking flow augmentation without constructing the layered 
   473   /// graph physically in which the blocking flow is computed.
   474   template <typename Graph, typename Num, typename CapMap, typename FlowMap>
   475   bool AugmentingFlow<Graph, Num, CapMap, FlowMap>::augmentOnBlockingFlow2()
   476   {
   477     bool _augment=false;
   478 
   479     ResGW res_graph(*g, *capacity, *flow);
   480     typename ResGW::ResCap res_cap(res_graph);
   481 
   482     //Potential map, for distances from s
   483     typename ResGW::template NodeMap<int> potential(res_graph, 0);
   484     typedef ConstMap<typename ResGW::Edge, int> Const1Map; 
   485     Const1Map const_1_map(1);
   486     TightEdgeFilterMap<ResGW, typename ResGW::template NodeMap<int>,
   487       Const1Map> tight_edge_filter(res_graph, potential, const_1_map);
   488 
   489     for (typename Graph::NodeIt n(*g); n!=INVALID; ++n) level.set(n, 0);
   490     BfsIterator<ResGW, ReachedMap> bfs(res_graph, level);
   491     bfs.pushAndSetReached(s);
   492 
   493     //computing distances from s in the residual graph
   494     while ( !bfs.finished() ) {
   495       ResGWEdge e=bfs;
   496       if (e!=INVALID && bfs.isBNodeNewlyReached())
   497 	potential.set(res_graph.head(e), potential[res_graph.tail(e)]+1);
   498       ++bfs;
   499     } 
   500 
   501     //Subgraph containing the edges on some shortest paths 
   502     //(i.e. tight edges)
   503     ConstMap<typename ResGW::Node, bool> true_map(true);
   504     typedef SubGraphWrapper<ResGW, ConstMap<typename ResGW::Node, bool>,
   505       TightEdgeFilterMap<ResGW, typename ResGW::template NodeMap<int>, 
   506       Const1Map> > FilterResGW;
   507     FilterResGW filter_res_graph(res_graph, true_map, tight_edge_filter);
   508 
   509     //Subgraph, which is able to delete edges which are already
   510     //met by the dfs
   511     typename FilterResGW::template NodeMap<typename FilterResGW::Edge>
   512       first_out_edges(filter_res_graph);
   513     for (typename FilterResGW::NodeIt v(filter_res_graph); v!=INVALID; ++v)
   514       first_out_edges.set
   515 	(v, typename FilterResGW::OutEdgeIt(filter_res_graph, v));
   516 
   517     typedef ErasingFirstGraphWrapper<FilterResGW, typename FilterResGW::
   518       template NodeMap<typename FilterResGW::Edge> > ErasingResGW;
   519     ErasingResGW erasing_res_graph(filter_res_graph, first_out_edges);
   520 
   521     bool __augment=true;
   522 
   523     while (__augment) {
   524 
   525       __augment=false;
   526       //computing blocking flow with dfs
   527       DfsIterator< ErasingResGW,
   528 	typename ErasingResGW::template NodeMap<bool> >
   529 	dfs(erasing_res_graph);
   530       typename ErasingResGW::
   531 	template NodeMap<typename ErasingResGW::Edge> pred(erasing_res_graph);
   532       pred.set(s, INVALID);
   533       //invalid iterators for sources
   534 
   535       typename ErasingResGW::template NodeMap<Num>
   536 	free1(erasing_res_graph);
   537 
   538       dfs.pushAndSetReached
   539 	/// \bug lemon 0.2
   540 	(typename ErasingResGW::Node
   541 	 (typename FilterResGW::Node
   542 	  (typename ResGW::Node(s)
   543 	   )
   544 	  )
   545 	 );
   546 	
   547       while (!dfs.finished()) {
   548 	++dfs;
   549 	if (typename ErasingResGW::Edge(dfs)!=INVALID) {
   550 	  if (dfs.isBNodeNewlyReached()) {
   551 	    
   552 	    typename ErasingResGW::Node v=erasing_res_graph.tail(dfs);
   553 	    typename ErasingResGW::Node w=erasing_res_graph.head(dfs);
   554 
   555 	    pred.set(w, typename ErasingResGW::Edge(dfs));
   556 	    if (pred[v]!=INVALID) {
   557 	      free1.set
   558 		(w, std::min(free1[v], res_cap
   559 			     [typename ErasingResGW::Edge(dfs)]));
   560 	    } else {
   561 	      free1.set
   562 		(w, res_cap
   563 		 [typename ErasingResGW::Edge(dfs)]);
   564 	    }
   565 
   566 	    if (w==t) {
   567 	      __augment=true;
   568 	      _augment=true;
   569 	      break;
   570 	    }
   571 	  } else {
   572 	    erasing_res_graph.erase(dfs);
   573 	  }
   574 	}
   575       }
   576 
   577       if (__augment) {
   578 	typename ErasingResGW::Node
   579 	  n=typename FilterResGW::Node(typename ResGW::Node(t));
   580 	Num augment_value=free1[n];
   581 	while (pred[n]!=INVALID) {
   582 	  typename ErasingResGW::Edge e=pred[n];
   583 	  res_graph.augment(e, augment_value);
   584 	  n=erasing_res_graph.tail(e);
   585 	  if (res_cap[e]==0)
   586 	    erasing_res_graph.erase(e);
   587 	}
   588       }
   589 
   590     } //while (__augment)
   591 
   592     status=AFTER_AUGMENTING;
   593     return _augment;
   594   }
   595 
   596 
   597 } //namespace lemon
   598 
   599 #endif //LEMON_AUGMENTING_FLOW_H
   600 
   601