# HG changeset patch
# User jacint
# Date 1077115381 0
# Node ID ba20e7ab1baaad2e2a4ae02795a11b47bfc8bac2
# Parent  a5127ecb2914901335800d8ca7eb745e00c86681
egyfajta preflow

diff -r a5127ecb2914 -r ba20e7ab1baa src/work/jacint/preflow_hl2.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/work/jacint/preflow_hl2.h	Wed Feb 18 14:43:01 2004 +0000
@@ -0,0 +1,403 @@
+// -*- C++ -*-
+/*
+preflow_hl2.h
+by jacint. 
+Runs the highest label variant of the preflow push algorithm with 
+running time O(n^2\sqrt(m)), with the 'empty level' and with the 
+heuristic that the bound b on the active nodes is not increased 
+only when b=0, when we put b=2*n-2.
+
+'A' is a parameter for the empty_level heuristic
+
+Member functions:
+
+void run() : runs the algorithm
+
+ The following functions should be used after run() was already run.
+
+T maxflow() : returns the value of a maximum flow
+
+T flowonedge(EdgeIt e) : for a fixed maximum flow x it returns x(e) 
+
+FlowMap allflow() : returns the fixed maximum flow x
+
+void mincut(CutMap& M) : sets M to the characteristic vector of a 
+     minimum cut. M should be a map of bools initialized to false.
+
+void min_mincut(CutMap& M) : sets M to the characteristic vector of the 
+     minimum min cut. M should be a map of bools initialized to false.
+
+void max_mincut(CutMap& M) : sets M to the characteristic vector of the 
+     maximum min cut. M should be a map of bools initialized to false.
+
+*/
+
+#ifndef PREFLOW_HL2_H
+#define PREFLOW_HL2_H
+
+#define A 1
+
+#include <vector>
+#include <stack>
+#include <queue>
+
+namespace marci {
+
+  template <typename Graph, typename T, 
+    typename FlowMap=typename Graph::EdgeMap<T>, typename CapMap=typename Graph::EdgeMap<T>, 
+    typename IntMap=typename Graph::NodeMap<int>, typename TMap=typename Graph::NodeMap<T> >
+  class preflow_hl2 {
+    
+    typedef typename Graph::NodeIt NodeIt;
+    typedef typename Graph::EdgeIt EdgeIt;
+    typedef typename Graph::EachNodeIt EachNodeIt;
+    typedef typename Graph::OutEdgeIt OutEdgeIt;
+    typedef typename Graph::InEdgeIt InEdgeIt;
+    
+    Graph& G;
+    NodeIt s;
+    NodeIt t;
+    FlowMap flow;
+    CapMap& capacity;  
+    T value;
+    
+  public:
+
+    preflow_hl2(Graph& _G, NodeIt _s, NodeIt _t, CapMap& _capacity) :
+      G(_G), s(_s), t(_t), flow(_G, 0), capacity(_capacity) { }
+
+
+    void run() {
+ 
+      bool no_end=true;
+      int n=G.nodeNum(); 
+      int b=n-2; 
+      /*
+	b is a bound on the highest level of an active node. 
+	In the beginning it is at most n-2.
+      */
+
+      IntMap level(G,n);      
+      TMap excess(G); 
+      
+      std::vector<int> numb(n+1);    
+      /*
+	The number of nodes on level i < n. It is
+	initialized to n+1, because of the reverse_bfs-part.
+      */
+
+      std::vector<std::stack<NodeIt> > stack(2*n-1);    
+      //Stack of the active nodes in level i.
+
+
+      /*Reverse_bfs from t, to find the starting level.*/
+      level.set(t,0);
+      std::queue<NodeIt> bfs_queue;
+      bfs_queue.push(t);
+
+      while (!bfs_queue.empty()) {
+
+	NodeIt v=bfs_queue.front();	
+	bfs_queue.pop();
+	int l=level.get(v)+1;
+
+	for(InEdgeIt e=G.template first<InEdgeIt>(v); e.valid(); ++e) {
+	  NodeIt w=G.tail(e);
+	  if ( level.get(w) == n ) {
+	    bfs_queue.push(w);
+	    ++numb[l];
+	    level.set(w, l);
+	  }
+	}
+      }
+      
+      level.set(s,n);
+
+
+
+      /* Starting flow. It is everywhere 0 at the moment. */     
+      for(OutEdgeIt e=G.template first<OutEdgeIt>(s); e.valid(); ++e) 
+	{
+	  if ( capacity.get(e) == 0 ) continue; 
+	  NodeIt w=G.head(e);
+	  if ( w!=s ) {	  
+	    if ( excess.get(w) == 0 && w!=t ) stack[level.get(w)].push(w); 
+	    flow.set(e, capacity.get(e)); 
+	    excess.set(w, excess.get(w)+capacity.get(e));
+	  } 
+	}
+
+      /* 
+	 End of preprocessing 
+      */
+
+
+
+      /*
+	Push/relabel on the highest level active nodes.
+      */	
+      /*While there exists an active node.*/
+      while (b) { 
+	if ( stack[b].empty() ) {
+	  if ( b==1 ) {
+	    if ( !no_end ) break; 
+	    else {
+	      b=2*n-2;
+	      no_end=false;
+	    }
+	  } 
+	  --b;
+	} else {
+	  
+	  no_end=true;
+	  
+	  NodeIt w=stack[b].top();        //w is a highest label active node.
+	  stack[b].pop();           
+	  int lev=level.get(w);
+	  int exc=excess.get(w);
+	  int newlevel=2*n-2;      //In newlevel we bound the next level of w.
+	  
+	  //  if ( level.get(w) < n ) { //Nem tudom ez mukodik-e
+	  for(OutEdgeIt e=G.template first<OutEdgeIt>(w); e.valid(); ++e) {
+	    
+	    if ( flow.get(e) == capacity.get(e) ) continue; 
+	    NodeIt v=G.head(e);            
+	    //e=wv	    
+	    
+	    if( lev > level.get(v) ) {      
+	      /*Push is allowed now*/
+	      
+	      if ( excess.get(v)==0 && v != s && v !=t ) 
+		stack[level.get(v)].push(v); 
+	      /*v becomes active.*/
+	      
+	      int cap=capacity.get(e);
+	      int flo=flow.get(e);
+	      int remcap=cap-flo;
+	      
+	      if ( remcap >= exc ) {       
+		/*A nonsaturating push.*/
+		
+		flow.set(e, flo+exc);
+		excess.set(v, excess.get(v)+exc);
+		exc=0;
+		break; 
+		
+	      } else { 
+		/*A saturating push.*/
+		
+		flow.set(e, cap );
+		excess.set(v, excess.get(v)+remcap);
+		exc-=remcap;
+	      }
+	    } else if ( newlevel > level.get(v) ) newlevel = level.get(v);
+	    
+	  } //for out edges wv 
+	
+	
+	if ( exc > 0 ) {	
+	  for( InEdgeIt e=G.template first<InEdgeIt>(w); e.valid(); ++e) {
+	    
+	    if( flow.get(e) == 0 ) continue; 
+	    NodeIt v=G.tail(e);  
+	    //e=vw
+	    
+	    if( lev > level.get(v) ) {  
+	      /*Push is allowed now*/
+	      
+	      if ( excess.get(v)==0 && v != s && v !=t) 
+		stack[level.get(v)].push(v); 
+	      /*v becomes active.*/
+	      
+	      int flo=flow.get(e);
+	      
+	      if ( flo >= exc ) { 
+		/*A nonsaturating push.*/
+		
+		flow.set(e, flo-exc);
+		excess.set(v, excess.get(v)+exc);
+		exc=0;
+		break; 
+	      } else {                                               
+		/*A saturating push.*/
+		
+		excess.set(v, excess.get(v)+flo);
+		exc-=flo;
+		flow.set(e,0);
+	      }  
+	    } else if ( newlevel > level.get(v) ) newlevel = level.get(v);
+	    
+	  } //for in edges vw
+	  
+	} // if w still has excess after the out edge for cycle
+	 
+	  excess.set(w, exc);
+	  
+
+	  /*
+	    Relabel
+	  */
+	  
+	  if ( exc > 0 ) {
+	    //now 'lev' is the old level of w
+	    level.set(w,++newlevel);
+	    
+	    if ( lev < n ) {
+	      --numb[lev];
+
+	      if ( !numb[lev] && lev < A*n ) {  //If the level of w gets empty. 
+		
+		for (EachNodeIt v=G.template first<EachNodeIt>(); v.valid() ; ++v) {
+		  if (level.get(v) > lev && level.get(v) < n ) level.set(v,n);  
+		}
+		for (int i=lev+1 ; i!=n ; ++i) numb[i]=0; 
+		if ( newlevel < n ) newlevel=n; 
+	      } else { 
+		if ( newlevel < n ) ++numb[newlevel]; 
+	      }
+	    } 
+	    
+	    stack[newlevel].push(w);
+
+	  }
+
+	} // if stack[b] is nonempty
+
+      } // while(b)
+
+
+      value = excess.get(t);
+      /*Max flow value.*/
+
+
+    } //void run()
+
+
+
+
+
+    /*
+      Returns the maximum value of a flow.
+     */
+
+    T maxflow() {
+      return value;
+    }
+
+
+
+    /*
+      For the maximum flow x found by the algorithm, it returns the flow value on Edge e, i.e. x(e). 
+    */
+
+    T flowonedge(EdgeIt e) {
+      return flow.get(e);
+    }
+
+
+
+    /*
+      Returns the maximum flow x found by the algorithm.
+    */
+
+    FlowMap allflow() {
+      return flow;
+    }
+
+
+
+
+    /*
+      Returns the minimum min cut, by a bfs from s in the residual graph.
+    */
+    
+    template<typename CutMap>
+    void mincut(CutMap& M) {
+    
+      std::queue<NodeIt> queue;
+      
+      M.set(s,true);      
+      queue.push(s);
+
+      while (!queue.empty()) {
+        NodeIt w=queue.front();
+	queue.pop();
+
+	for(OutEdgeIt e=G.template first<OutEdgeIt>(w) ; e.valid(); ++e) {
+	  NodeIt v=G.head(e);
+	  if (!M.get(v) && flow.get(e) < capacity.get(e) ) {
+	    queue.push(v);
+	    M.set(v, true);
+	  }
+	} 
+
+	for(InEdgeIt e=G.template first<InEdgeIt>(w) ; e.valid(); ++e) {
+	  NodeIt v=G.tail(e);
+	  if (!M.get(v) && flow.get(e) > 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 max_mincut(CutMap& M) {
+    
+      std::queue<NodeIt> queue;
+      
+      M.set(t,true);        
+      queue.push(t);
+
+      while (!queue.empty()) {
+        NodeIt w=queue.front();
+	queue.pop();
+
+	for(InEdgeIt e=G.template first<InEdgeIt>(w) ; e.valid(); ++e) {
+	  NodeIt v=G.tail(e);
+	  if (!M.get(v) && flow.get(e) < capacity.get(e) ) {
+	    queue.push(v);
+	    M.set(v, true);
+	  }
+	}
+
+	for(OutEdgeIt e=G.template first<OutEdgeIt>(w) ; e.valid(); ++e) {
+	  NodeIt v=G.head(e);
+	  if (!M.get(v) && flow.get(e) > 0 ) {
+	    queue.push(v);
+	    M.set(v, true);
+	  }
+	}
+      }
+
+      for(EachNodeIt v=G.template first<EachNodeIt>() ; v.valid(); ++v) {
+	M.set(v, !M.get(v));
+      }
+
+    }
+
+
+
+    template<typename CutMap>
+    void min_mincut(CutMap& M) {
+      mincut(M);
+    }
+
+
+
+  };
+}//namespace marci
+#endif 
+
+
+
+