# HG changeset patch
# User jacint
# Date 1077229713 0
# Node ID 294cb99af985542df6734947b81028c37abfa7a6
# Parent  d2ac583ed1956d8c3517c54fc9e05542dc63c210
The best etik-ol flow alg so far.

diff -r d2ac583ed195 -r 294cb99af985 src/work/jacint/preflow_hl4.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/work/jacint/preflow_hl4.h	Thu Feb 19 22:28:33 2004 +0000
@@ -0,0 +1,486 @@
+// -*- C++ -*-
+/*
+preflow_hl4.h
+by jacint. 
+Runs the two phase highest label preflow push algorithm. In phase 0
+we maintain in a list the nodes in level i < n, and we maintain a 
+bound k on the max level i < n containing a node, so we can do
+the gap heuristic fast. Phase 1 is the same. (The algorithm is the 
+same as preflow.hl3, the only diff is that here we use the gap
+heuristic with the list of the nodes on level i, and not a bfs form the
+upgraded node.)
+
+In phase 1 we shift everything downwards by n.
+
+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 a maximum flow
+
+void allflow(FlowMap& _flow ) : returns a maximum flow
+
+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_HL4_H
+#define PREFLOW_HL4_H
+
+#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> >
+  class preflow_hl4 {
+    
+    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_hl4(Graph& _G, NodeIt _s, NodeIt _t, CapMap& _capacity) :
+      G(_G), s(_s), t(_t), flow(_G, 0), capacity(_capacity) { }
+
+
+    void run() {
+ 
+      bool phase=0;
+      int n=G.nodeNum(); 
+      int k=n-2;
+      int b=k;
+      /*
+	b is a bound on the highest level of the stack. 
+	k is a bound on the highest nonempty level i < n.
+      */
+
+      typename Graph::NodeMap<int> level(G,n);      
+      typename Graph::NodeMap<T> excess(G); 
+      std::vector<std::stack<NodeIt> > stack(n);    
+      //Stack of the active nodes in level i < n.
+      //We use it in both phases.
+
+      typename Graph::NodeMap<NodeIt> left(G);
+      typename Graph::NodeMap<NodeIt> right(G);
+      std::vector<NodeIt> level_list(n);
+      /*
+	Needed for the list of the 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);
+	    NodeIt first=level_list[l];
+	    if ( first != 0 ) left.set(first,w);
+	    right.set(w,first);
+	    level_list[l]=w;
+	    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) 
+	{
+	  T c=capacity.get(e);
+	  if ( c == 0 ) continue;
+	  NodeIt w=G.head(e);
+	  if ( level.get(w) < n ) {	  
+	    if ( excess.get(w) == 0 && w!=t ) stack[level.get(w)].push(w); 
+	    flow.set(e, c); 
+	    excess.set(w, excess.get(w)+c);
+	  }
+	}
+      /* 
+	 End of preprocessing 
+      */
+
+
+      /*
+	Push/relabel on the highest level active nodes.
+      */	
+      while ( true ) {
+
+	if ( b == 0 ) {
+	  if ( phase ) break;
+	  
+	  /*
+	    In the end of phase 0 we apply a bfs from s in
+	    the residual graph.
+	  */
+	  phase=1;
+	  level.set(s,0);
+	  std::queue<NodeIt> bfs_queue;
+	  bfs_queue.push(s);
+	  
+	  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) {
+	      if ( capacity.get(e) == flow.get(e) ) continue;
+	      NodeIt u=G.tail(e);
+	      if ( level.get(u) >= n ) { 
+		bfs_queue.push(u);
+		level.set(u, l);
+		if ( excess.get(u) > 0 ) stack[l].push(u);
+	      }
+	    }
+
+	    for(OutEdgeIt e=G.template first<OutEdgeIt>(v); e.valid(); ++e) {
+	      if ( 0 == flow.get(e) ) continue;
+	      NodeIt u=G.head(e);
+	      if ( level.get(u) >= n ) { 
+		bfs_queue.push(u);
+		level.set(u, l);
+		if ( excess.get(u) > 0 ) stack[l].push(u);
+	      }
+	    }
+	  }
+	  b=n-2;
+	}
+
+
+	if ( stack[b].empty() ) --b;
+	else {
+	  
+	  NodeIt w=stack[b].top();        //w is a highest label active node.
+	  stack[b].pop();           
+	  int lev=level.get(w);
+	  T exc=excess.get(w);
+	  int newlevel=n;          //In newlevel we bound the next level of w.
+	  
+	  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!=t && v!=s ) 
+		stack[level.get(v)].push(v); 
+	      /*v becomes active.*/
+	      
+	      T cap=capacity.get(e);
+	      T flo=flow.get(e);
+	      T 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!=t && v!=s ) 
+		stack[level.get(v)].push(v); 
+	      /*v becomes active.*/
+	      
+	      T 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
+	
+	  if ( phase ) {
+	    level.set(w,++newlevel);
+	    stack[newlevel].push(w);
+	    b=newlevel;
+	  } else {
+	    //unlacing
+	    NodeIt right_n=right.get(w);
+	    NodeIt left_n=left.get(w);
+
+	    if ( right_n != 0 ) {
+	      if ( left_n != 0 ) {
+		right.set(left_n, right_n);
+		left.set(right_n, left_n);
+	      } else {
+		level_list[lev]=right_n;
+		left.set(right_n, 0);
+	      } 
+	    } else {
+	      if ( left_n != 0 ) {
+		right.set(left_n, 0);
+	      } else { 
+		level_list[lev]=0;
+	      } 
+	    }
+		
+
+	    if ( level_list[lev]==0 ) {
+
+	      for (int i=lev; i!=k ; ) {
+		NodeIt v=level_list[++i];
+		while ( v != 0 ) {
+		  level.set(v,n);
+		  v=right.get(v);
+		}
+		level_list[i]=0;
+	      }	     
+
+	      level.set(w,n);
+
+	      b=--lev;
+	      k=b;
+
+	    } else {
+
+	      if ( newlevel == n ) {
+		level.set(w,n);
+	      } else {
+		
+		level.set(w,++newlevel);
+		stack[newlevel].push(w);
+		b=newlevel;
+		if ( k < newlevel ) ++k;
+		NodeIt first=level_list[newlevel];
+		if ( first != 0 ) left.set(first,w);
+		right.set(w,first);
+		left.set(w,0);
+		level_list[newlevel]=w;
+	      }
+	    }
+	  } //phase 0
+	} // if ( exc > 0 )
+ 
+	
+	} // if stack[b] is nonempty
+	
+      } // while(true)
+
+
+      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);
+    }
+
+
+
+    FlowMap allflow() {
+      return flow;
+    }
+
+
+    
+    void allflow(FlowMap& _flow ) {
+      for(EachNodeIt v=G.template first<EachNodeIt>() ; v.valid(); ++v)
+	_flow.set(v,flow.get(v));
+    }
+
+
+
+    /*
+      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 
+
+
+
+