// -*- C++ -*-

 /*

 Heuristics: 

  2 phase

  gap

  list 'level_list' on the nodes on level i implemented by hand

  stack 'active' on the active nodes on level i

  runs heuristic 'highest label' for H1*n relabels

  runs heuristic 'bound decrease' for H0*n relabels, starts with 'highest label'

 Parameters H0 and H1 are initialized to 20 and 1.

 Constructors:

 Preflow(Graph, Node, Node, CapMap, FlowMap, bool) : bool must be false if 

      FlowMap is not constant zero, and should be true if it is

 Members:

 void run()

 Num flowValue() : returns the value of a maximum flow

 void minMinCut(CutMap& M) : sets M to the characteristic vector of the 

      minimum min cut. M should be a map of bools initialized to false. ??Is it OK?

 void maxMinCut(CutMap& M) : sets M to the characteristic vector of the 

      maximum min cut. M should be a map of bools initialized to false.

 void minCut(CutMap& M) : sets M to the characteristic vector of 

      a min cut. M should be a map of bools initialized to false.

 */

 #ifndef HUGO_PREFLOW_H

 #define HUGO_PREFLOW_H

 #define H0 20

 #define H1 1

 #include <vector>

 #include <queue>

 #include <stack>

 #include <graph_wrapper.h>

 #include <bfs_iterator.h>

 #include <invalid.h>

 #include <maps.h>

 #include <for_each_macros.h>

 namespace hugo {

   template <typename Graph, typename Num, 

 	    typename CapMap=typename Graph::template EdgeMap<Num>, 

             typename FlowMap=typename Graph::template EdgeMap<Num> >

   class MaxFlow {

     typedef typename Graph::Node Node;

     typedef typename Graph::NodeIt NodeIt;

     typedef typename Graph::OutEdgeIt OutEdgeIt;

     typedef typename Graph::InEdgeIt InEdgeIt;

     typedef typename std::vector<std::stack<Node> > VecStack;

     typedef typename Graph::template NodeMap<Node> NNMap;

     typedef typename std::vector<Node> VecNode;

     const Graph* g;

     Node s;

     Node t;

     const CapMap* capacity;  

     FlowMap* flow;

     int n;      //the number of nodes of G

     typedef ResGraphWrapper<const Graph, Num, CapMap, FlowMap> ResGW;

     typedef typename ResGW::OutEdgeIt ResGWOutEdgeIt;

     typedef typename ResGW::Edge ResGWEdge;

     //typedef typename ResGW::template NodeMap<bool> ReachedMap;

     typedef typename Graph::template NodeMap<int> ReachedMap;

     ReachedMap level;

     //level works as a bool map in augmenting path algorithms 

     //and is used by bfs for storing reached information.

     //In preflow, it shows levels of nodes.

     //typename Graph::template NodeMap<int> level;    

     typename Graph::template NodeMap<Num> excess; 

   public:

     enum flowEnum{

       ZERO_FLOW=0,

       GEN_FLOW=1,

       PREFLOW=2

     };

     MaxFlow(const Graph& _G, Node _s, Node _t, const CapMap& _capacity, 

 	    FlowMap& _flow) :

       g(&_G), s(_s), t(_t), capacity(&_capacity), 

       flow(&_flow), n(_G.nodeNum()), level(_G), excess(_G,0) {}

     void run() {

       preflow( ZERO_FLOW );

     }

     void preflow( flowEnum fe ) {

       preflowPhase0(fe);

       preflowPhase1();

     }

     void preflowPhase0( flowEnum fe );

     void preflowPhase1();

     bool augmentOnShortestPath();

     template<typename MutableGraph> bool augmentOnBlockingFlow();

     bool augmentOnBlockingFlow2();

     /// Returns the actual flow value.

     /// More precisely, it returns the negative excess of s, thus 

     /// this works also for preflows.

     Num flowValue() { 

       Num a=0;

       FOR_EACH_INC_LOC(OutEdgeIt, e, *g, s) a+=(*flow)[e];

       FOR_EACH_INC_LOC(InEdgeIt, e, *g, s) a-=(*flow)[e];

       return a;

     }

     //should be used only between preflowPhase0 and preflowPhase1

     template<typename _CutMap>

     void actMinCut(_CutMap& M) {

       NodeIt v;

       for(g->first(v); g->valid(v); g->next(v)) 

       if ( level[v] < n ) {

 	M.set(v,false);

       } else {

 	M.set(v,true);

       }

     }

     /*

       Returns the minimum min cut, by a bfs from s in the residual graph.

     */

     template<typename _CutMap>

     void minMinCut(_CutMap& M) {

       std::queue<Node> queue;

       M.set(s,true);      

       queue.push(s);

       while (!queue.empty()) {

         Node w=queue.front();

 	queue.pop();

 	OutEdgeIt e;

 	for(g->first(e,w) ; g->valid(e); g->next(e)) {

 	  Node v=g->head(e);

 	  if (!M[v] && (*flow)[e] < (*capacity)[e] ) {

 	    queue.push(v);

 	    M.set(v, true);

 	  }

 	} 

 	InEdgeIt f;

 	for(g->first(f,w) ; g->valid(f); g->next(f)) {

 	  Node v=g->tail(f);

 	  if (!M[v] && (*flow)[f] > 0 ) {

 	    queue.push(v);

 	    M.set(v, true);

 	  }

 	} 

       }

     }

     /*

       Returns the maximum min cut, by a reverse bfs 

       from t in the residual graph.

     */

     template<typename _CutMap>

     void maxMinCut(_CutMap& M) {

       NodeIt v;

       for(g->first(v) ; g->valid(v); g->next(v)) {

 	M.set(v, true);

       }

       std::queue<Node> queue;

       M.set(t,false);        

       queue.push(t);

       while (!queue.empty()) {

         Node w=queue.front();

 	queue.pop();

 	InEdgeIt e;

 	for(g->first(e,w) ; g->valid(e); g->next(e)) {

 	  Node v=g->tail(e);

 	  if (M[v] && (*flow)[e] < (*capacity)[e] ) {

 	    queue.push(v);

 	    M.set(v, false);

 	  }

 	}

 	OutEdgeIt f;

 	for(g->first(f,w) ; g->valid(f); g->next(f)) {

 	  Node v=g->head(f);

 	  if (M[v] && (*flow)[f] > 0 ) {

 	    queue.push(v);

 	    M.set(v, false);

 	  }

 	}

       }

     }

     template<typename CutMap>

     void minCut(CutMap& M) {

       minMinCut(M);

     }

     void resetTarget(Node _t) {t=_t;}

     void resetSource(Node _s) {s=_s;}

     void resetCap(const CapMap& _cap) {

       capacity=&_cap;

     }

     void resetFlow(FlowMap& _flow) {

       flow=&_flow;

     }

   private:

     int push(Node w, VecStack& active) {

       int lev=level[w];

       Num exc=excess[w];

       int newlevel=n;       //bound on the next level of w

       OutEdgeIt e;

       for(g->first(e,w); g->valid(e); g->next(e)) {

 	if ( (*flow)[e] >= (*capacity)[e] ) continue; 

 	Node v=g->head(e);            

 	if( lev > level[v] ) { //Push is allowed now

 	  if ( excess[v]<=0 && v!=t && v!=s ) {

 	    int lev_v=level[v];

 	    active[lev_v].push(v);

 	  }

 	  Num cap=(*capacity)[e];

 	  Num flo=(*flow)[e];

 	  Num remcap=cap-flo;

 	  if ( remcap >= exc ) { //A nonsaturating push.

 	    flow->set(e, flo+exc);

 	    excess.set(v, excess[v]+exc);

 	    exc=0;

 	    break; 

 	  } else { //A saturating push.

 	    flow->set(e, cap);

 	    excess.set(v, excess[v]+remcap);

 	    exc-=remcap;

 	  }

 	} else if ( newlevel > level[v] ) newlevel = level[v];

       } //for out edges wv 

       if ( exc > 0 ) {	

 	InEdgeIt e;

 	for(g->first(e,w); g->valid(e); g->next(e)) {

 	  if( (*flow)[e] <= 0 ) continue; 

 	  Node v=g->tail(e); 

 	  if( lev > level[v] ) { //Push is allowed now

 	    if ( excess[v]<=0 && v!=t && v!=s ) {

 	      int lev_v=level[v];

 	      active[lev_v].push(v);

 	    }

 	    Num flo=(*flow)[e];

 	    if ( flo >= exc ) { //A nonsaturating push.

 	      flow->set(e, flo-exc);

 	      excess.set(v, excess[v]+exc);

 	      exc=0;

 	      break; 

 	    } else {  //A saturating push.

 	      excess.set(v, excess[v]+flo);

 	      exc-=flo;

 	      flow->set(e,0);

 	    }  

 	  } else if ( newlevel > level[v] ) newlevel = level[v];

 	} //for in edges vw

       } // if w still has excess after the out edge for cycle

       excess.set(w, exc);

       return newlevel;

      }

     void preflowPreproc ( flowEnum fe, VecStack& active, 

 			  VecNode& level_list, NNMap& left, NNMap& right ) {

       std::queue<Node> bfs_queue;

       switch ( fe ) {

       case ZERO_FLOW: 

 	{

 	  //Reverse_bfs from t, to find the starting level.

 	  level.set(t,0);

 	  bfs_queue.push(t);

 	  while (!bfs_queue.empty()) {

 	    Node v=bfs_queue.front();	

 	    bfs_queue.pop();

 	    int l=level[v]+1;

 	    InEdgeIt e;

 	    for(g->first(e,v); g->valid(e); g->next(e)) {

 	      Node w=g->tail(e);

 	      if ( level[w] == n && w != s ) {

 		bfs_queue.push(w);

 		Node first=level_list[l];

 		if ( g->valid(first) ) left.set(first,w);

 		right.set(w,first);

 		level_list[l]=w;

 		level.set(w, l);

 	      }

 	    }

 	  }

 	  //the starting flow

 	  OutEdgeIt e;

 	  for(g->first(e,s); g->valid(e); g->next(e)) 

 	    {

 	      Num c=(*capacity)[e];

 	      if ( c <= 0 ) continue;

 	      Node w=g->head(e);

 	      if ( level[w] < n ) {	  

 		if ( excess[w] <= 0 && w!=t ) active[level[w]].push(w);

 		flow->set(e, c); 

 		excess.set(w, excess[w]+c);

 	      }

 	    }

 	  break;

 	}

       case GEN_FLOW:

       case PREFLOW:

 	{

 	  //Reverse_bfs from t in the residual graph, 

 	  //to find the starting level.

 	  level.set(t,0);

 	  bfs_queue.push(t);

 	  while (!bfs_queue.empty()) {

 	    Node v=bfs_queue.front();	

 	    bfs_queue.pop();

 	    int l=level[v]+1;

 	    InEdgeIt e;

 	    for(g->first(e,v); g->valid(e); g->next(e)) {

 	      if ( (*capacity)[e] <= (*flow)[e] ) continue;

 	      Node w=g->tail(e);

 	      if ( level[w] == n && w != s ) {

 		bfs_queue.push(w);

 		Node first=level_list[l];

 		if ( g->valid(first) ) left.set(first,w);

 		right.set(w,first);

 		level_list[l]=w;

 		level.set(w, l);

 	      }

 	    }

 	    OutEdgeIt f;

 	    for(g->first(f,v); g->valid(f); g->next(f)) {

 	      if ( 0 >= (*flow)[f] ) continue;

 	      Node w=g->head(f);

 	      if ( level[w] == n && w != s ) {

 		bfs_queue.push(w);

 		Node first=level_list[l];

 		if ( g->valid(first) ) left.set(first,w);

 		right.set(w,first);

 		level_list[l]=w;

 		level.set(w, l);

 	      }

 	    }

 	  }

 	  //the starting flow

 	  OutEdgeIt e;

 	  for(g->first(e,s); g->valid(e); g->next(e)) 

 	    {

 	      Num rem=(*capacity)[e]-(*flow)[e];

 	      if ( rem <= 0 ) continue;

 	      Node w=g->head(e);

 	      if ( level[w] < n ) {	  

 		if ( excess[w] <= 0 && w!=t ) active[level[w]].push(w);

 		flow->set(e, (*capacity)[e]); 

 		excess.set(w, excess[w]+rem);

 	      }

 	    }

 	  InEdgeIt f;

 	  for(g->first(f,s); g->valid(f); g->next(f)) 

 	    {

 	      if ( (*flow)[f] <= 0 ) continue;

 	      Node w=g->tail(f);

 	      if ( level[w] < n ) {	  

 		if ( excess[w] <= 0 && w!=t ) active[level[w]].push(w);

 		excess.set(w, excess[w]+(*flow)[f]);

 		flow->set(f, 0); 

 	      }

 	    }  

 	  break;

 	} //case PREFLOW

       }

     } //preflowPreproc

     void relabel(Node w, int newlevel, VecStack& active,  

 		 VecNode& level_list, NNMap& left, 

 		 NNMap& right, int& b, int& k, bool what_heur ) 

     {

       Num lev=level[w];	

       Node right_n=right[w];

       Node left_n=left[w];

       //unlacing starts

       if ( g->valid(right_n) ) {

 	if ( g->valid(left_n) ) {

 	  right.set(left_n, right_n);

 	  left.set(right_n, left_n);

 	} else {

 	  level_list[lev]=right_n;   

 	  left.set(right_n, INVALID);

 	} 

       } else {

 	if ( g->valid(left_n) ) {

 	  right.set(left_n, INVALID);

 	} else { 

 	  level_list[lev]=INVALID;   

 	} 

       } 

       //unlacing ends

       if ( !g->valid(level_list[lev]) ) {

 	//gapping starts

 	for (int i=lev; i!=k ; ) {

 	  Node v=level_list[++i];

 	  while ( g->valid(v) ) {

 	    level.set(v,n);

 	    v=right[v];

 	  }

 	  level_list[i]=INVALID;

 	  if ( !what_heur ) {

 	    while ( !active[i].empty() ) {

 	      active[i].pop();    //FIXME: ezt szebben kene

 	    }

 	  }	     

 	}

 	level.set(w,n);

 	b=lev-1;

 	k=b;

 	//gapping ends

       } else {

 	if ( newlevel == n ) level.set(w,n); 

 	else {

 	  level.set(w,++newlevel);

 	  active[newlevel].push(w);

 	  if ( what_heur ) b=newlevel;

 	  if ( k < newlevel ) ++k;      //now k=newlevel

 	  Node first=level_list[newlevel];

 	  if ( g->valid(first) ) left.set(first,w);

 	  right.set(w,first);

 	  left.set(w,INVALID);

 	  level_list[newlevel]=w;

 	}

       }

     } //relabel

     template<typename MapGraphWrapper> 

     class DistanceMap {

     protected:

       const MapGraphWrapper* g;

       typename MapGraphWrapper::template NodeMap<int> dist; 

     public:

       DistanceMap(MapGraphWrapper& _g) : g(&_g), dist(*g, g->nodeNum()) { }

       void set(const typename MapGraphWrapper::Node& n, int a) { 

 	dist.set(n, a); 

       }

       int operator[](const typename MapGraphWrapper::Node& n) 

 	{ return dist[n]; }

 //       int get(const typename MapGraphWrapper::Node& n) const { 

 // 	return dist[n]; }

 //       bool get(const typename MapGraphWrapper::Edge& e) const { 

 // 	return (dist.get(g->tail(e))<dist.get(g->head(e))); }

       bool operator[](const typename MapGraphWrapper::Edge& e) const { 

 	return (dist[g->tail(e)]<dist[g->head(e)]); 

       }

     };

   };

   template <typename Graph, typename Num, typename CapMap, typename FlowMap>

   void MaxFlow<Graph, Num, CapMap, FlowMap>::preflowPhase0( flowEnum fe ) 

   {

       int heur0=(int)(H0*n);  //time while running 'bound decrease' 

       int heur1=(int)(H1*n);  //time while running 'highest label'

       int heur=heur1;         //starting time interval (#of relabels)

       int numrelabel=0;

       bool what_heur=1;       

       //It is 0 in case 'bound decrease' and 1 in case 'highest label'

       bool end=false;     

       //Needed for 'bound decrease', true means no active nodes are above bound b.

       int k=n-2;  //bound on the highest level under n containing a node

       int b=k;    //bound on the highest level under n of an active node

       VecStack active(n);

       NNMap left(*g, INVALID);

       NNMap right(*g, INVALID);

       VecNode level_list(n,INVALID);

       //List of the nodes in level i<n, set to n.

       NodeIt v;

       for(g->first(v); g->valid(v); g->next(v)) level.set(v,n);

       //setting each node to level n

       switch ( fe ) {

       case PREFLOW:

 	{

 	  //counting the excess

 	  NodeIt v;

 	  for(g->first(v); g->valid(v); g->next(v)) {

 	    Num exc=0;

 	    InEdgeIt e;

 	    for(g->first(e,v); g->valid(e); g->next(e)) exc+=(*flow)[e];

 	    OutEdgeIt f;

 	    for(g->first(f,v); g->valid(f); g->next(f)) exc-=(*flow)[f];

 	    excess.set(v,exc);	  

 	    //putting the active nodes into the stack

 	    int lev=level[v];

 	    if ( exc > 0 && lev < n && v != t ) active[lev].push(v);

 	  }

 	  break;

 	}

       case GEN_FLOW:

 	{

 	  //Counting the excess of t

 	  Num exc=0;

 	  InEdgeIt e;

 	  for(g->first(e,t); g->valid(e); g->next(e)) exc+=(*flow)[e];

 	  OutEdgeIt f;

 	  for(g->first(f,t); g->valid(f); g->next(f)) exc-=(*flow)[f];

 	  excess.set(t,exc);	

 	  break;

 	}

       default:

 	break;

       }

       preflowPreproc( fe, active, level_list, left, right );

       //End of preprocessing 

       //Push/relabel on the highest level active nodes.

       while ( true ) {

 	if ( b == 0 ) {

 	  if ( !what_heur && !end && k > 0 ) {

 	    b=k;

 	    end=true;

 	  } else break;

 	}

 	if ( active[b].empty() ) --b; 

 	else {

 	  end=false;  

 	  Node w=active[b].top();

 	  active[b].pop();

 	  int newlevel=push(w,active);

 	  if ( excess[w] > 0 ) relabel(w, newlevel, active, level_list, 

 				       left, right, b, k, what_heur);

 	  ++numrelabel; 

 	  if ( numrelabel >= heur ) {

 	    numrelabel=0;

 	    if ( what_heur ) {

 	      what_heur=0;

 	      heur=heur0;

 	      end=false;

 	    } else {

 	      what_heur=1;

 	      heur=heur1;

 	      b=k; 

 	    }

 	  }

 	} 

       } 

     }

   template <typename Graph, typename Num, typename CapMap, typename FlowMap>

   void MaxFlow<Graph, Num, CapMap, FlowMap>::preflowPhase1() 

   {

       int k=n-2;  //bound on the highest level under n containing a node

       int b=k;    //bound on the highest level under n of an active node

       VecStack active(n);

       level.set(s,0);

       std::queue<Node> bfs_queue;

       bfs_queue.push(s);

       while (!bfs_queue.empty()) {

 	Node v=bfs_queue.front();	

 	bfs_queue.pop();

 	int l=level[v]+1;

 	InEdgeIt e;

 	for(g->first(e,v); g->valid(e); g->next(e)) {

 	  if ( (*capacity)[e] <= (*flow)[e] ) continue;

 	  Node u=g->tail(e);

 	  if ( level[u] >= n ) { 

 	    bfs_queue.push(u);

 	    level.set(u, l);

 	    if ( excess[u] > 0 ) active[l].push(u);

 	  }

 	}

 	OutEdgeIt f;

 	for(g->first(f,v); g->valid(f); g->next(f)) {

 	  if ( 0 >= (*flow)[f] ) continue;

 	  Node u=g->head(f);

 	  if ( level[u] >= n ) { 

 	    bfs_queue.push(u);

 	    level.set(u, l);

 	    if ( excess[u] > 0 ) active[l].push(u);

 	  }

 	}

       }

       b=n-2;

       while ( true ) {

 	if ( b == 0 ) break;

 	if ( active[b].empty() ) --b; 

 	else {

 	  Node w=active[b].top();

 	  active[b].pop();

 	  int newlevel=push(w,active);	  

 	  //relabel

 	  if ( excess[w] > 0 ) {

 	    level.set(w,++newlevel);

 	    active[newlevel].push(w);

 	    b=newlevel;

 	  }

 	}  // if stack[b] is nonempty

       } // while(true)

     }

   template <typename Graph, typename Num, typename CapMap, typename FlowMap>

   bool MaxFlow<Graph, Num, CapMap, FlowMap>::augmentOnShortestPath() 

   {

       ResGW res_graph(*g, *capacity, *flow);

       bool _augment=false;

       //ReachedMap level(res_graph);

       FOR_EACH_LOC(typename Graph::NodeIt, e, *g) level.set(e, 0);

       BfsIterator<ResGW, ReachedMap> bfs(res_graph, level);

       bfs.pushAndSetReached(s);

       typename ResGW::template NodeMap<ResGWEdge> pred(res_graph); 

       pred.set(s, INVALID);

       typename ResGW::template NodeMap<Num> free(res_graph);

       //searching for augmenting path

       while ( !bfs.finished() ) { 

 	ResGWOutEdgeIt e=bfs;

 	if (res_graph.valid(e) && bfs.isBNodeNewlyReached()) {

 	  Node v=res_graph.tail(e);

 	  Node w=res_graph.head(e);

 	  pred.set(w, e);

 	  if (res_graph.valid(pred[v])) {

 	    free.set(w, std::min(free[v], res_graph.resCap(e)));

 	  } else {

 	    free.set(w, res_graph.resCap(e)); 

 	  }

 	  if (res_graph.head(e)==t) { _augment=true; break; }

 	}

 	++bfs;

       } //end of searching augmenting path

       if (_augment) {

 	Node n=t;

 	Num augment_value=free[t];

 	while (res_graph.valid(pred[n])) { 

 	  ResGWEdge e=pred[n];

 	  res_graph.augment(e, augment_value); 

 	  n=res_graph.tail(e);

 	}

       }

       return _augment;

     }

   template <typename Graph, typename Num, typename CapMap, typename FlowMap>

   template<typename MutableGraph> 

   bool MaxFlow<Graph, Num, CapMap, FlowMap>::augmentOnBlockingFlow() 

   {      

       typedef MutableGraph MG;

       bool _augment=false;

       ResGW res_graph(*g, *capacity, *flow);

       //bfs for distances on the residual graph

       //ReachedMap level(res_graph);

       FOR_EACH_LOC(typename Graph::NodeIt, e, *g) level.set(e, 0);

       BfsIterator<ResGW, ReachedMap> bfs(res_graph, level);

       bfs.pushAndSetReached(s);

       typename ResGW::template NodeMap<int> 

 	dist(res_graph); //filled up with 0's

       //F will contain the physical copy of the residual graph

       //with the set of edges which are on shortest paths

       MG F;

       typename ResGW::template NodeMap<typename MG::Node> 

 	res_graph_to_F(res_graph);

       {

 	typename ResGW::NodeIt n;

 	for(res_graph.first(n); res_graph.valid(n); res_graph.next(n)) {

 	  res_graph_to_F.set(n, F.addNode());

 	}

       }

       typename MG::Node sF=res_graph_to_F[s];

       typename MG::Node tF=res_graph_to_F[t];

       typename MG::template EdgeMap<ResGWEdge> original_edge(F);

       typename MG::template EdgeMap<Num> residual_capacity(F);

       while ( !bfs.finished() ) { 

 	ResGWOutEdgeIt e=bfs;

 	if (res_graph.valid(e)) {

 	  if (bfs.isBNodeNewlyReached()) {

 	    dist.set(res_graph.head(e), dist[res_graph.tail(e)]+1);

 	    typename MG::Edge f=F.addEdge(res_graph_to_F[res_graph.tail(e)], res_graph_to_F[res_graph.head(e)]);

 	    original_edge.update();

 	    original_edge.set(f, e);

 	    residual_capacity.update();

 	    residual_capacity.set(f, res_graph.resCap(e));

 	  } else {

 	    if (dist[res_graph.head(e)]==(dist[res_graph.tail(e)]+1)) {

 	      typename MG::Edge f=F.addEdge(res_graph_to_F[res_graph.tail(e)], res_graph_to_F[res_graph.head(e)]);

 	      original_edge.update();

 	      original_edge.set(f, e);

 	      residual_capacity.update();

 	      residual_capacity.set(f, res_graph.resCap(e));

 	    }

 	  }

 	}

 	++bfs;

       } //computing distances from s in the residual graph

       bool __augment=true;

       while (__augment) {

 	__augment=false;

 	//computing blocking flow with dfs

 	DfsIterator< MG, typename MG::template NodeMap<bool> > dfs(F);

 	typename MG::template NodeMap<typename MG::Edge> pred(F);

 	pred.set(sF, INVALID);

 	//invalid iterators for sources

 	typename MG::template NodeMap<Num> free(F);

 	dfs.pushAndSetReached(sF);      

 	while (!dfs.finished()) {

 	  ++dfs;

 	  if (F.valid(/*typename MG::OutEdgeIt*/(dfs))) {

 	    if (dfs.isBNodeNewlyReached()) {

 	      typename MG::Node v=F.aNode(dfs);

 	      typename MG::Node w=F.bNode(dfs);

 	      pred.set(w, dfs);

 	      if (F.valid(pred[v])) {

 		free.set(w, std::min(free[v], residual_capacity[dfs]));

 	      } else {

 		free.set(w, residual_capacity[dfs]); 

 	      }

 	      if (w==tF) { 

 		__augment=true; 

 		_augment=true;

 		break; 

 	      }

 	    } else {

 	      F.erase(/*typename MG::OutEdgeIt*/(dfs));

 	    }

 	  } 

 	}

 	if (__augment) {

 	  typename MG::Node n=tF;

 	  Num augment_value=free[tF];

 	  while (F.valid(pred[n])) { 

 	    typename MG::Edge e=pred[n];

 	    res_graph.augment(original_edge[e], augment_value); 

 	    n=F.tail(e);

 	    if (residual_capacity[e]==augment_value) 

 	      F.erase(e); 

 	    else 

 	      residual_capacity.set(e, residual_capacity[e]-augment_value);

 	  }

 	}

       }

       return _augment;

     }

   template <typename Graph, typename Num, typename CapMap, typename FlowMap>

   bool MaxFlow<Graph, Num, CapMap, FlowMap>::augmentOnBlockingFlow2() 

   {

       bool _augment=false;

       ResGW res_graph(*g, *capacity, *flow);

       //ReachedMap level(res_graph);

       FOR_EACH_LOC(typename Graph::NodeIt, e, *g) level.set(e, 0);

       BfsIterator<ResGW, ReachedMap> bfs(res_graph, level);

       bfs.pushAndSetReached(s);

       DistanceMap<ResGW> dist(res_graph);

       while ( !bfs.finished() ) { 

  	ResGWOutEdgeIt e=bfs;

  	if (res_graph.valid(e) && bfs.isBNodeNewlyReached()) {

  	  dist.set(res_graph.head(e), dist[res_graph.tail(e)]+1);

  	}

 	++bfs;

       } //computing distances from s in the residual graph

       //Subgraph containing the edges on some shortest paths

       ConstMap<typename ResGW::Node, bool> true_map(true);

       typedef SubGraphWrapper<ResGW, ConstMap<typename ResGW::Node, bool>, 

 	DistanceMap<ResGW> > FilterResGW;

       FilterResGW filter_res_graph(res_graph, true_map, dist);

       //Subgraph, which is able to delete edges which are already 

       //met by the dfs

       typename FilterResGW::template NodeMap<typename FilterResGW::OutEdgeIt> 

  	first_out_edges(filter_res_graph);

       typename FilterResGW::NodeIt v;

       for(filter_res_graph.first(v); filter_res_graph.valid(v); 

  	  filter_res_graph.next(v)) 

       {

  	typename FilterResGW::OutEdgeIt e;

  	filter_res_graph.first(e, v);

  	first_out_edges.set(v, e);

       }

       typedef ErasingFirstGraphWrapper<FilterResGW, typename FilterResGW::

 	template NodeMap<typename FilterResGW::OutEdgeIt> > ErasingResGW;

       ErasingResGW erasing_res_graph(filter_res_graph, first_out_edges);

       bool __augment=true;

       while (__augment) {

  	__augment=false;

   	//computing blocking flow with dfs

   	DfsIterator< ErasingResGW, 

 	  typename ErasingResGW::template NodeMap<bool> > 

   	  dfs(erasing_res_graph);

  	typename ErasingResGW::

 	  template NodeMap<typename ErasingResGW::OutEdgeIt> 

 	  pred(erasing_res_graph); 

  	pred.set(s, INVALID);

   	//invalid iterators for sources

   	typename ErasingResGW::template NodeMap<Num> 

 	  free1(erasing_res_graph);

  	dfs.pushAndSetReached(

 	  typename ErasingResGW::Node(

 	    typename FilterResGW::Node(

 	      typename ResGW::Node(s)

 	      )

 	    )

 	  );

  	while (!dfs.finished()) {

  	  ++dfs;

  	  if (erasing_res_graph.valid(

  		typename ErasingResGW::OutEdgeIt(dfs))) 

  	  { 

   	    if (dfs.isBNodeNewlyReached()) {

  	      typename ErasingResGW::Node v=erasing_res_graph.aNode(dfs);

  	      typename ErasingResGW::Node w=erasing_res_graph.bNode(dfs);

  	      pred.set(w, /*typename ErasingResGW::OutEdgeIt*/(dfs));

  	      if (erasing_res_graph.valid(pred[v])) {

  		free1.set(w, std::min(free1[v], res_graph.resCap(

 				       typename ErasingResGW::OutEdgeIt(dfs))));

  	      } else {

  		free1.set(w, res_graph.resCap(

 			   typename ErasingResGW::OutEdgeIt(dfs))); 

  	      }

  	      if (w==t) { 

  		__augment=true; 

  		_augment=true;

  		break; 

  	      }

  	    } else {

  	      erasing_res_graph.erase(dfs);

 	    }

 	  }

 	}	

   	if (__augment) {

    	  typename ErasingResGW::Node n=typename FilterResGW::Node(typename ResGW::Node(t));

 // 	  typename ResGW::NodeMap<Num> a(res_graph);

 // 	  typename ResGW::Node b;

 // 	  Num j=a[b];

 // 	  typename FilterResGW::NodeMap<Num> a1(filter_res_graph);

 // 	  typename FilterResGW::Node b1;

 // 	  Num j1=a1[b1];

 // 	  typename ErasingResGW::NodeMap<Num> a2(erasing_res_graph);

 // 	  typename ErasingResGW::Node b2;

 // 	  Num j2=a2[b2];

  	  Num augment_value=free1[n];

  	  while (erasing_res_graph.valid(pred[n])) { 

  	    typename ErasingResGW::OutEdgeIt e=pred[n];

  	    res_graph.augment(e, augment_value);

  	    n=erasing_res_graph.tail(e);

  	    if (res_graph.resCap(e)==0)

  	      erasing_res_graph.erase(e);

 	}

       }

       } //while (__augment) 

       return _augment;

     }

 } //namespace hugo

 #endif //HUGO_PREFLOW_H