jacint@437: // -*- C++ -*-
jacint@437: 
jacint@437: //run gyorsan tudna adni a minmincutot a 2 fazis elejen , ne vegyuk be konstruktorba egy cutmapet?
jacint@437: //constzero jo igy?
jacint@437: 
jacint@437: //majd marci megmondja betegyem-e bfs-t meg resgraphot
jacint@437: 
jacint@437: //constzero helyett az kell hogy flow-e vagy csak preflow, ha flow akor csak
jacint@437: //excess[t]-t kell szmaolni
jacint@437: 
jacint@437: /*
jacint@437: Heuristics: 
jacint@437:  2 phase
jacint@437:  gap
jacint@437:  list 'level_list' on the nodes on level i implemented by hand
jacint@437:  stack 'active' on the active nodes on level i implemented by hand
jacint@437:  runs heuristic 'highest label' for H1*n relabels
jacint@437:  runs heuristic 'bound decrease' for H0*n relabels, starts with 'highest label'
jacint@437:  
jacint@437: Parameters H0 and H1 are initialized to 20 and 10.
jacint@437: 
jacint@437: Constructors:
jacint@437: 
jacint@437: Preflow(Graph, Node, Node, CapMap, FlowMap, bool) : bool must be false if 
jacint@437:      FlowMap is not constant zero, and should be true if it is
jacint@437: 
jacint@437: Members:
jacint@437: 
jacint@437: void run()
jacint@437: 
jacint@437: T flowValue() : returns the value of a maximum flow
jacint@437: 
jacint@437: void minMinCut(CutMap& M) : sets M to the characteristic vector of the 
jacint@437:      minimum min cut. M should be a map of bools initialized to false.
jacint@437: 
jacint@437: void maxMinCut(CutMap& M) : sets M to the characteristic vector of the 
jacint@437:      maximum min cut. M should be a map of bools initialized to false.
jacint@437: 
jacint@437: void minCut(CutMap& M) : sets M to the characteristic vector of 
jacint@437:      a min cut. M should be a map of bools initialized to false.
jacint@437: 
jacint@437: FIXME reset
jacint@437: 
jacint@437: */
jacint@437: 
alpar@921: #ifndef LEMON_PREFLOW_H
alpar@921: #define LEMON_PREFLOW_H
jacint@437: 
jacint@437: #define H0 20
jacint@437: #define H1 1
jacint@437: 
jacint@437: #include <vector>
jacint@437: #include <queue>
jacint@437: #include <stack>
jacint@437: 
alpar@921: namespace lemon {
jacint@437: 
jacint@437:   template <typename Graph, typename T, 
jacint@437: 	    typename CapMap=typename Graph::template EdgeMap<T>, 
jacint@437:             typename FlowMap=typename Graph::template EdgeMap<T> >
jacint@437:   class Preflow {
jacint@437:     
jacint@437:     typedef typename Graph::Node Node;
jacint@437:     typedef typename Graph::Edge Edge;
jacint@437:     typedef typename Graph::NodeIt NodeIt;
jacint@437:     typedef typename Graph::OutEdgeIt OutEdgeIt;
jacint@437:     typedef typename Graph::InEdgeIt InEdgeIt;
jacint@437:     
jacint@437:     const Graph& G;
jacint@437:     Node s;
jacint@437:     Node t;
jacint@437:     const CapMap& capacity;  
jacint@437:     FlowMap& flow;
jacint@437:     T value;
jacint@437:     bool constzero;
jacint@437:     bool isflow;
jacint@437: 
jacint@437:   public:
jacint@437:     Preflow(Graph& _G, Node _s, Node _t, CapMap& _capacity, 
jacint@437: 	    FlowMap& _flow, bool _constzero, bool _isflow ) :
jacint@437:       G(_G), s(_s), t(_t), capacity(_capacity), flow(_flow), constzero(_constzero), isflow(_isflow) {}
jacint@437:     
jacint@437:     
jacint@437:     void run() {
jacint@437:       
jacint@437:       value=0;                //for the subsequent runs
jacint@437: 
jacint@437:       bool phase=0;        //phase 0 is the 1st phase, phase 1 is the 2nd
jacint@437:       int n=G.nodeNum(); 
jacint@437:       int heur0=(int)(H0*n);  //time while running 'bound decrease' 
jacint@437:       int heur1=(int)(H1*n);  //time while running 'highest label'
jacint@437:       int heur=heur1;         //starting time interval (#of relabels)
jacint@437:       bool what_heur=1;       
jacint@437:       /*
jacint@437: 	what_heur is 0 in case 'bound decrease' 
jacint@437: 	and 1 in case 'highest label'
jacint@437:       */
jacint@437:       bool end=false;     
jacint@437:       /*
jacint@437: 	Needed for 'bound decrease', 'true'
jacint@437: 	means no active nodes are above bound b.
jacint@437:       */
jacint@437:       int relabel=0;
jacint@437:       int k=n-2;  //bound on the highest level under n containing a node
jacint@437:       int b=k;    //bound on the highest level under n of an active node
jacint@437:       
jacint@437:       typename Graph::template NodeMap<int> level(G,n);      
jacint@437:       typename Graph::template NodeMap<T> excess(G); 
jacint@437: 
jacint@437:       std::vector<std::stack<Node> > active(n);
jacint@437:       /*      std::vector<Node> active(n-1,INVALID);
jacint@437:       typename Graph::template NodeMap<Node> next(G,INVALID);
jacint@437:       //Stack of the active nodes in level i < n.
jacint@437:       //We use it in both phases.*/
jacint@437: 
jacint@437:       typename Graph::template NodeMap<Node> left(G,INVALID);
jacint@437:       typename Graph::template NodeMap<Node> right(G,INVALID);
jacint@437:       std::vector<Node> level_list(n,INVALID);
jacint@437:       /*
jacint@437: 	List of the nodes in level i<n.
jacint@437:       */
jacint@437: 
jacint@437: 
jacint@437:       if ( constzero ) {
jacint@437:      
jacint@437: 	/*Reverse_bfs from t, to find the starting level.*/
jacint@437: 	level.set(t,0);
jacint@437: 	std::queue<Node> bfs_queue;
jacint@437: 	bfs_queue.push(t);
jacint@437: 	
jacint@437: 	while (!bfs_queue.empty()) {
jacint@437: 	  
jacint@437: 	  Node v=bfs_queue.front();	
jacint@437: 	  bfs_queue.pop();
jacint@437: 	  int l=level[v]+1;
jacint@437: 	  
jacint@437: 	  InEdgeIt e;
jacint@437: 	  for(G.first(e,v); G.valid(e); G.next(e)) {
jacint@437: 	    Node w=G.tail(e);
jacint@437: 	    if ( level[w] == n && w != s ) {
jacint@437: 	      bfs_queue.push(w);
jacint@437: 	      Node first=level_list[l];
jacint@437: 	      if ( G.valid(first) ) left.set(first,w);
jacint@437: 	      right.set(w,first);
jacint@437: 	      level_list[l]=w;
jacint@437: 	      level.set(w, l);
jacint@437: 	    }
jacint@437: 	  }
jacint@437: 	}
jacint@437: 
jacint@437: 	//the starting flow
jacint@437: 	OutEdgeIt e;
jacint@437: 	for(G.first(e,s); G.valid(e); G.next(e)) 
jacint@437: 	{
jacint@437: 	  T c=capacity[e];
jacint@437: 	  if ( c == 0 ) continue;
jacint@437: 	  Node w=G.head(e);
jacint@437: 	  if ( level[w] < n ) {	  
jacint@437: 	    if ( excess[w] == 0 && w!=t ) active[level[w]].push(w);
jacint@437: 	    flow.set(e, c); 
jacint@437: 	    excess.set(w, excess[w]+c);
jacint@437: 	  }
jacint@437: 	}
jacint@437:       }
jacint@437:       else 
jacint@437:       {
jacint@437: 	
jacint@437: 	/*
jacint@437: 	  Reverse_bfs from t in the residual graph, 
jacint@437: 	  to find the starting level.
jacint@437: 	*/
jacint@437: 	level.set(t,0);
jacint@437: 	std::queue<Node> bfs_queue;
jacint@437: 	bfs_queue.push(t);
jacint@437: 	
jacint@437: 	while (!bfs_queue.empty()) {
jacint@437: 	  
jacint@437: 	  Node v=bfs_queue.front();	
jacint@437: 	  bfs_queue.pop();
jacint@437: 	  int l=level[v]+1;
jacint@437: 	  
jacint@437: 	  InEdgeIt e;
jacint@437: 	  for(G.first(e,v); G.valid(e); G.next(e)) {
jacint@437: 	    if ( capacity[e] == flow[e] ) continue;
jacint@437: 	    Node w=G.tail(e);
jacint@437: 	    if ( level[w] == n && w != s ) {
jacint@437: 	      bfs_queue.push(w);
jacint@437: 	      Node first=level_list[l];
jacint@437: 	      if ( G.valid(first) ) left.set(first,w);
jacint@437: 	      right.set(w,first);
jacint@437: 	      level_list[l]=w;
jacint@437: 	      level.set(w, l);
jacint@437: 	    }
jacint@437: 	  }
jacint@437: 	    
jacint@437: 	  OutEdgeIt f;
jacint@437: 	  for(G.first(f,v); G.valid(f); G.next(f)) {
jacint@437: 	    if ( 0 == flow[f] ) continue;
jacint@437: 	    Node w=G.head(f);
jacint@437: 	    if ( level[w] == n && w != s ) {
jacint@437: 	      bfs_queue.push(w);
jacint@437: 	      Node first=level_list[l];
jacint@437: 	      if ( G.valid(first) ) left.set(first,w);
jacint@437: 	      right.set(w,first);
jacint@437: 	      level_list[l]=w;
jacint@437: 	      level.set(w, l);
jacint@437: 	    }
jacint@437: 	  }
jacint@437: 	}
jacint@437:       
jacint@437: 	
jacint@437: 	/*
jacint@437: 	  Counting the excess
jacint@437: 	*/
jacint@437: 
jacint@437: 	if ( !isflow ) {
jacint@437: 	  NodeIt v;
jacint@437: 	  for(G.first(v); G.valid(v); G.next(v)) {
jacint@437: 	    T exc=0;
jacint@437: 	    
jacint@437: 	    InEdgeIt e;
jacint@437: 	    for(G.first(e,v); G.valid(e); G.next(e)) exc+=flow[e];
jacint@437: 	    OutEdgeIt f;
jacint@437: 	    for(G.first(f,v); G.valid(f); G.next(f)) exc-=flow[f];
jacint@437: 	    
jacint@437: 	    excess.set(v,exc);	  
jacint@437: 	    
jacint@437: 	    //putting the active nodes into the stack
jacint@437: 	    int lev=level[v];
jacint@437: 	    if ( exc > 0 && lev < n && v != t ) active[lev].push(v);
jacint@437: 	  }
jacint@437: 	} else {
jacint@437: 	  T exc=0;
jacint@437: 	    
jacint@437: 	  InEdgeIt e;
jacint@437: 	  for(G.first(e,t); G.valid(e); G.next(e)) exc+=flow[e];
jacint@437: 	  OutEdgeIt f;
jacint@437: 	  for(G.first(f,t); G.valid(f); G.next(f)) exc-=flow[f];
jacint@437: 
jacint@437: 	  excess.set(t,exc);	  
jacint@437: 	}
jacint@437: 
jacint@437: 
jacint@437: 	//the starting flow
jacint@437: 	OutEdgeIt e;
jacint@437: 	for(G.first(e,s); G.valid(e); G.next(e)) 
jacint@437: 	{
jacint@437: 	  T rem=capacity[e]-flow[e];
jacint@437: 	  if ( rem == 0 ) continue;
jacint@437: 	  Node w=G.head(e);
jacint@437: 	  if ( level[w] < n ) {	  
jacint@437: 	    if ( excess[w] == 0 && w!=t ) active[level[w]].push(w);
jacint@437: 	    flow.set(e, capacity[e]); 
jacint@437: 	    excess.set(w, excess[w]+rem);
jacint@437: 	  }
jacint@437: 	}
jacint@437: 	
jacint@437: 	InEdgeIt f;
jacint@437: 	for(G.first(f,s); G.valid(f); G.next(f)) 
jacint@437: 	{
jacint@437: 	  if ( flow[f] == 0 ) continue;
jacint@437: 	  Node w=G.tail(f);
jacint@437: 	  if ( level[w] < n ) {	  
jacint@437: 	    if ( excess[w] == 0 && w!=t ) active[level[w]].push(w);
jacint@437: 	    excess.set(w, excess[w]+flow[f]);
jacint@437: 	    flow.set(f, 0); 
jacint@437: 	  }
jacint@437: 	}
jacint@437:       }
jacint@437: 
jacint@437: 
jacint@437: 
jacint@437: 
jacint@437:       /* 
jacint@437: 	 End of preprocessing 
jacint@437:       */
jacint@437: 
jacint@437: 
jacint@437: 
jacint@437:       /*
jacint@437: 	Push/relabel on the highest level active nodes.
jacint@437:       */	
jacint@437:       while ( true ) {
jacint@437: 	
jacint@437: 	if ( b == 0 ) {
jacint@437: 	  if ( phase ) break;
jacint@437: 	  
jacint@437: 	  if ( !what_heur && !end && k > 0 ) {
jacint@437: 	    b=k;
jacint@437: 	    end=true;
jacint@437: 	  } else {
jacint@437: 	    phase=1;
jacint@437: 	    level.set(s,0);
jacint@437: 	    std::queue<Node> bfs_queue;
jacint@437: 	    bfs_queue.push(s);
jacint@437: 	    
jacint@437: 	    while (!bfs_queue.empty()) {
jacint@437: 	      
jacint@437: 	      Node v=bfs_queue.front();	
jacint@437: 	      bfs_queue.pop();
jacint@437: 	      int l=level[v]+1;
jacint@437: 	      
jacint@437: 	      InEdgeIt e;
jacint@437: 	      for(G.first(e,v); G.valid(e); G.next(e)) {
jacint@437: 		if ( capacity[e] == flow[e] ) continue;
jacint@437: 		Node u=G.tail(e);
jacint@437: 		if ( level[u] >= n ) { 
jacint@437: 		  bfs_queue.push(u);
jacint@437: 		  level.set(u, l);
jacint@437: 		  if ( excess[u] > 0 ) active[l].push(u);
jacint@437: 		}
jacint@437: 	      }
jacint@437: 	    
jacint@437: 	      OutEdgeIt f;
jacint@437: 	      for(G.first(f,v); G.valid(f); G.next(f)) {
jacint@437: 		if ( 0 == flow[f] ) continue;
jacint@437: 		Node u=G.head(f);
jacint@437: 		if ( level[u] >= n ) { 
jacint@437: 		  bfs_queue.push(u);
jacint@437: 		  level.set(u, l);
jacint@437: 		  if ( excess[u] > 0 ) active[l].push(u);
jacint@437: 		}
jacint@437: 	      }
jacint@437: 	    }
jacint@437: 	    b=n-2;
jacint@437: 	    }
jacint@437: 	    
jacint@437: 	}
jacint@437: 	  
jacint@437: 
jacint@437: 	///	  
jacint@437: 	if ( active[b].empty() ) --b; 
jacint@437: 	else {
jacint@437: 	  end=false;  
jacint@437: 
jacint@437: 	  Node w=active[b].top();
jacint@437: 	  active[b].pop();
jacint@437: 	  int lev=level[w];
jacint@437: 	  T exc=excess[w];
jacint@437: 	  int newlevel=n;       //bound on the next level of w
jacint@437: 	  
jacint@437: 	  OutEdgeIt e;
jacint@437: 	  for(G.first(e,w); G.valid(e); G.next(e)) {
jacint@437: 	    
jacint@437: 	    if ( flow[e] == capacity[e] ) continue; 
jacint@437: 	    Node v=G.head(e);            
jacint@437: 	    //e=wv	    
jacint@437: 	    
jacint@437: 	    if( lev > level[v] ) {      
jacint@437: 	      /*Push is allowed now*/
jacint@437: 	      
jacint@437: 	      if ( excess[v]==0 && v!=t && v!=s ) {
jacint@437: 		int lev_v=level[v];
jacint@437: 		active[lev_v].push(v);
jacint@437: 	      }
jacint@437: 	      
jacint@437: 	      T cap=capacity[e];
jacint@437: 	      T flo=flow[e];
jacint@437: 	      T remcap=cap-flo;
jacint@437: 	      
jacint@437: 	      if ( remcap >= exc ) {       
jacint@437: 		/*A nonsaturating push.*/
jacint@437: 		
jacint@437: 		flow.set(e, flo+exc);
jacint@437: 		excess.set(v, excess[v]+exc);
jacint@437: 		exc=0;
jacint@437: 		break; 
jacint@437: 		
jacint@437: 	      } else { 
jacint@437: 		/*A saturating push.*/
jacint@437: 		
jacint@437: 		flow.set(e, cap);
jacint@437: 		excess.set(v, excess[v]+remcap);
jacint@437: 		exc-=remcap;
jacint@437: 	      }
jacint@437: 	    } else if ( newlevel > level[v] ){
jacint@437: 	      newlevel = level[v];
jacint@437: 	    }	    
jacint@437: 	    
jacint@437: 	  } //for out edges wv 
jacint@437: 	
jacint@437: 	
jacint@437: 	if ( exc > 0 ) {	
jacint@437: 	  InEdgeIt e;
jacint@437: 	  for(G.first(e,w); G.valid(e); G.next(e)) {
jacint@437: 	    
jacint@437: 	    if( flow[e] == 0 ) continue; 
jacint@437: 	    Node v=G.tail(e);  
jacint@437: 	    //e=vw
jacint@437: 	    
jacint@437: 	    if( lev > level[v] ) {  
jacint@437: 	      /*Push is allowed now*/
jacint@437: 	      
jacint@437: 	      if ( excess[v]==0 && v!=t && v!=s ) {
jacint@437: 		int lev_v=level[v];
jacint@437: 		active[lev_v].push(v);
jacint@437: 	      }
jacint@437: 	      
jacint@437: 	      T flo=flow[e];
jacint@437: 	      
jacint@437: 	      if ( flo >= exc ) { 
jacint@437: 		/*A nonsaturating push.*/
jacint@437: 		
jacint@437: 		flow.set(e, flo-exc);
jacint@437: 		excess.set(v, excess[v]+exc);
jacint@437: 		exc=0;
jacint@437: 		break; 
jacint@437: 	      } else {                                               
jacint@437: 		/*A saturating push.*/
jacint@437: 		
jacint@437: 		excess.set(v, excess[v]+flo);
jacint@437: 		exc-=flo;
jacint@437: 		flow.set(e,0);
jacint@437: 	      }  
jacint@437: 	    } else if ( newlevel > level[v] ) {
jacint@437: 	      newlevel = level[v];
jacint@437: 	    }	    
jacint@437: 	  } //for in edges vw
jacint@437: 	  
jacint@437: 	} // if w still has excess after the out edge for cycle
jacint@437: 	
jacint@437: 	excess.set(w, exc);
jacint@437: 	///	push
jacint@437: 
jacint@437:  
jacint@437: 	/*
jacint@437: 	  Relabel
jacint@437: 	*/
jacint@437: 	
jacint@437: 
jacint@437: 	if ( exc > 0 ) {
jacint@437: 	  //now 'lev' is the old level of w
jacint@437: 	
jacint@437: 	  if ( phase ) {
jacint@437: 	    level.set(w,++newlevel);
jacint@437: 	    active[newlevel].push(w);
jacint@437: 	    b=newlevel;
jacint@437: 	  } else {
jacint@437: 	    //unlacing starts
jacint@437: 	    Node right_n=right[w];
jacint@437: 	    Node left_n=left[w];
jacint@437: 
jacint@437: 	    if ( G.valid(right_n) ) {
jacint@437: 	      if ( G.valid(left_n) ) {
jacint@437: 		right.set(left_n, right_n);
jacint@437: 		left.set(right_n, left_n);
jacint@437: 	      } else {
jacint@437: 		level_list[lev]=right_n;   
jacint@437: 		left.set(right_n, INVALID);
jacint@437: 	      } 
jacint@437: 	    } else {
jacint@437: 	      if ( G.valid(left_n) ) {
jacint@437: 		right.set(left_n, INVALID);
jacint@437: 	      } else { 
jacint@437: 		level_list[lev]=INVALID;   
jacint@437: 	      } 
jacint@437: 	    } 
jacint@437: 	    //unlacing ends
jacint@437: 		
jacint@437: 	    if ( !G.valid(level_list[lev]) ) {
jacint@437: 	      
jacint@437: 	       //gapping starts
jacint@437: 	      for (int i=lev; i!=k ; ) {
jacint@437: 		Node v=level_list[++i];
jacint@437: 		while ( G.valid(v) ) {
jacint@437: 		  level.set(v,n);
jacint@437: 		  v=right[v];
jacint@437: 		}
jacint@437: 		level_list[i]=INVALID;
jacint@437: 		if ( !what_heur ) {
jacint@437: 		  while ( !active[i].empty() ) {
jacint@437: 		    active[i].pop();    //FIXME: ezt szebben kene
jacint@437: 		  }
jacint@437: 		}	     
jacint@437: 	      }
jacint@437: 
jacint@437: 	      level.set(w,n);
jacint@437: 	      b=lev-1;
jacint@437: 	      k=b;
jacint@437: 	      //gapping ends
jacint@437: 	    
jacint@437: 	    } else {
jacint@437: 	      
jacint@437: 	      if ( newlevel == n ) level.set(w,n); 
jacint@437: 	      else {
jacint@437: 		level.set(w,++newlevel);
jacint@437: 		active[newlevel].push(w);
jacint@437: 		if ( what_heur ) b=newlevel;
jacint@437: 		if ( k < newlevel ) ++k;      //now k=newlevel
jacint@437: 		Node first=level_list[newlevel];
jacint@437: 		if ( G.valid(first) ) left.set(first,w);
jacint@437: 		right.set(w,first);
jacint@437: 		left.set(w,INVALID);
jacint@437: 		level_list[newlevel]=w;
jacint@437: 	      }
jacint@437: 	    }
jacint@437: 
jacint@437: 
jacint@437: 	    ++relabel; 
jacint@437: 	    if ( relabel >= heur ) {
jacint@437: 	      relabel=0;
jacint@437: 	      if ( what_heur ) {
jacint@437: 		what_heur=0;
jacint@437: 		heur=heur0;
jacint@437: 		end=false;
jacint@437: 	      } else {
jacint@437: 		what_heur=1;
jacint@437: 		heur=heur1;
jacint@437: 		b=k; 
jacint@437: 	      }
jacint@437: 	    }
jacint@437: 	  } //phase 0
jacint@437: 	  
jacint@437: 	  
jacint@437: 	} // if ( exc > 0 )
jacint@437: 	  
jacint@437: 	
jacint@437: 	}  // if stack[b] is nonempty
jacint@437: 	
jacint@437:       } // while(true)
jacint@437: 
jacint@437: 
jacint@437:       value = excess[t];
jacint@437:       /*Max flow value.*/
jacint@437:      
jacint@437:     } //void run()
jacint@437: 
jacint@437: 
jacint@437: 
jacint@437: 
jacint@437: 
jacint@437:     /*
jacint@437:       Returns the maximum value of a flow.
jacint@437:      */
jacint@437: 
jacint@437:     T flowValue() {
jacint@437:       return value;
jacint@437:     }
jacint@437: 
jacint@437: 
jacint@437:     FlowMap Flow() {
jacint@437:       return flow;
jacint@437:       }
jacint@437: 
jacint@437: 
jacint@437:     void Flow(FlowMap& _flow ) {
jacint@437:       NodeIt v;
jacint@437:       for(G.first(v) ; G.valid(v); G.next(v))
jacint@437: 	_flow.set(v,flow[v]);
jacint@437:     }
jacint@437: 
jacint@437: 
jacint@437: 
jacint@437:     /*
jacint@437:       Returns the minimum min cut, by a bfs from s in the residual graph.
jacint@437:     */
jacint@437:    
jacint@437:     template<typename _CutMap>
jacint@437:     void minMinCut(_CutMap& M) {
jacint@437:     
jacint@437:       std::queue<Node> queue;
jacint@437:       
jacint@437:       M.set(s,true);      
jacint@437:       queue.push(s);
jacint@437: 
jacint@437:       while (!queue.empty()) {
jacint@437:         Node w=queue.front();
jacint@437: 	queue.pop();
jacint@437: 
jacint@437: 	OutEdgeIt e;
jacint@437: 	for(G.first(e,w) ; G.valid(e); G.next(e)) {
jacint@437: 	  Node v=G.head(e);
jacint@437: 	  if (!M[v] && flow[e] < capacity[e] ) {
jacint@437: 	    queue.push(v);
jacint@437: 	    M.set(v, true);
jacint@437: 	  }
jacint@437: 	} 
jacint@437: 
jacint@437: 	InEdgeIt f;
jacint@437: 	for(G.first(f,w) ; G.valid(f); G.next(f)) {
jacint@437: 	  Node v=G.tail(f);
jacint@437: 	  if (!M[v] && flow[f] > 0 ) {
jacint@437: 	    queue.push(v);
jacint@437: 	    M.set(v, true);
jacint@437: 	  }
jacint@437: 	} 
jacint@437:       }
jacint@437:     }
jacint@437: 
jacint@437: 
jacint@437:   
jacint@437:     /*
jacint@437:       Returns the maximum min cut, by a reverse bfs 
jacint@437:       from t in the residual graph.
jacint@437:     */
jacint@437:     
jacint@437:     template<typename _CutMap>
jacint@437:     void maxMinCut(_CutMap& M) {
jacint@437:     
jacint@437:       std::queue<Node> queue;
jacint@437:       
jacint@437:       M.set(t,true);        
jacint@437:       queue.push(t);
jacint@437: 
jacint@437:       while (!queue.empty()) {
jacint@437:         Node w=queue.front();
jacint@437: 	queue.pop();
jacint@437: 
jacint@437: 
jacint@437: 	InEdgeIt e;
jacint@437: 	for(G.first(e,w) ; G.valid(e); G.next(e)) {
jacint@437: 	  Node v=G.tail(e);
jacint@437: 	  if (!M[v] && flow[e] < capacity[e] ) {
jacint@437: 	    queue.push(v);
jacint@437: 	    M.set(v, true);
jacint@437: 	  }
jacint@437: 	}
jacint@437: 	
jacint@437: 	OutEdgeIt f;
jacint@437: 	for(G.first(f,w) ; G.valid(f); G.next(f)) {
jacint@437: 	  Node v=G.head(f);
jacint@437: 	  if (!M[v] && flow[f] > 0 ) {
jacint@437: 	    queue.push(v);
jacint@437: 	    M.set(v, true);
jacint@437: 	  }
jacint@437: 	}
jacint@437:       }
jacint@437: 
jacint@437:       NodeIt v;
jacint@437:       for(G.first(v) ; G.valid(v); G.next(v)) {
jacint@437: 	M.set(v, !M[v]);
jacint@437:       }
jacint@437: 
jacint@437:     }
jacint@437: 
jacint@437: 
jacint@437: 
jacint@437:     template<typename CutMap>
jacint@437:     void minCut(CutMap& M) {
jacint@437:       minMinCut(M);
jacint@437:     }
jacint@437: 
jacint@437:     
jacint@437:     void resetTarget (Node _t) {t=_t;}
jacint@437:     void resetSource (Node _s) {s=_s;}
jacint@437:    
jacint@437:     void resetCap (CapMap _cap) {capacity=_cap;}
jacint@437: 
jacint@437:     void resetFlow (FlowMap _flow, bool _constzero) {
jacint@437:       flow=_flow;
jacint@437:       constzero=_constzero;
jacint@437:     }
jacint@437: 
jacint@437: 
jacint@437: 
jacint@437:   };
jacint@437: 
alpar@921: } //namespace lemon
jacint@437: 
jacint@437: #endif //PREFLOW_H
jacint@437: 
jacint@437: 
jacint@437: 
jacint@437: