diff -r 2d6c8075d9d0 -r 818510fa3d99 src/hugo/preflow.h
--- a/src/hugo/preflow.h	Wed Sep 29 14:12:26 2004 +0000
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,819 +0,0 @@
-/* -*- C++ -*-
- * src/hugo/preflow.h - Part of HUGOlib, a generic C++ optimization library
- *
- * Copyright (C) 2004 Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
- * (Egervary Combinatorial Optimization Research Group, EGRES).
- *
- * Permission to use, modify and distribute this software is granted
- * provided that this copyright notice appears in all copies. For
- * precise terms see the accompanying LICENSE file.
- *
- * This software is provided "AS IS" with no warranty of any kind,
- * express or implied, and with no claim as to its suitability for any
- * purpose.
- *
- */
-
-#ifndef HUGO_PREFLOW_H
-#define HUGO_PREFLOW_H
-
-#include <vector>
-#include <queue>
-
-#include <hugo/invalid.h>
-#include <hugo/maps.h>
-
-/// \file
-/// \ingroup flowalgs
-/// Implementation of the preflow algorithm.
-
-namespace hugo {
-
-  /// \addtogroup flowalgs
-  /// @{                                                   
-
-  ///%Preflow algorithms class.
-
-  ///This class provides an implementation of the \e preflow \e
-  ///algorithm producing a flow of maximum value in a directed
-  ///graph. The preflow algorithms are the fastest max flow algorithms
-  ///up to now. The \e source node, the \e target node, the \e
-  ///capacity of the edges and the \e starting \e flow value of the
-  ///edges should be passed to the algorithm through the
-  ///constructor. It is possible to change these quantities using the
-  ///functions \ref setSource, \ref setTarget, \ref setCap and \ref
-  ///setFlow.
-  ///
-  ///After running \ref hugo::Preflow::phase1() "phase1()"
-  ///or \ref hugo::Preflow::run() "run()", the maximal flow
-  ///value can be obtained by calling \ref flowValue(). The minimum
-  ///value cut can be written into a <tt>bool</tt> node map by
-  ///calling \ref minCut(). (\ref minMinCut() and \ref maxMinCut() writes
-  ///the inclusionwise minimum and maximum of the minimum value cuts,
-  ///resp.)
-  ///
-  ///\param Graph The directed graph type the algorithm runs on.
-  ///\param Num The number type of the capacities and the flow values.
-  ///\param CapMap The capacity map type.
-  ///\param FlowMap The flow map type.
-  ///
-  ///\author Jacint Szabo 
-  template <typename Graph, typename Num,
-	    typename CapMap=typename Graph::template EdgeMap<Num>,
-            typename FlowMap=typename Graph::template EdgeMap<Num> >
-  class Preflow {
-  protected:
-    typedef typename Graph::Node Node;
-    typedef typename Graph::NodeIt NodeIt;
-    typedef typename Graph::EdgeIt EdgeIt;
-    typedef typename Graph::OutEdgeIt OutEdgeIt;
-    typedef typename Graph::InEdgeIt InEdgeIt;
-
-    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
-    
-    typename Graph::template NodeMap<int> level;  
-    typename Graph::template NodeMap<Num> excess;
-
-    // constants used for heuristics
-    static const int H0=20;
-    static const int H1=1;
-
-    public:
-
-    ///Indicates the property of the starting flow map.
-
-    ///Indicates the property of the starting flow map. The meanings are as follows:
-    ///- \c ZERO_FLOW: constant zero flow
-    ///- \c GEN_FLOW: any flow, i.e. the sum of the in-flows equals to
-    ///the sum of the out-flows in every node except the \e source and
-    ///the \e target.
-    ///- \c PRE_FLOW: any preflow, i.e. the sum of the in-flows is at 
-    ///least the sum of the out-flows in every node except the \e source.
-    ///- \c NO_FLOW: indicates an unspecified edge map. \c flow will be 
-    ///set to the constant zero flow in the beginning of
-    ///the algorithm in this case.
-    ///
-    enum FlowEnum{
-      NO_FLOW,
-      ZERO_FLOW,
-      GEN_FLOW,
-      PRE_FLOW
-    };
-
-    ///Indicates the state of the preflow algorithm.
-
-    ///Indicates the state of the preflow algorithm. The meanings are as follows:
-    ///- \c AFTER_NOTHING: before running the algorithm or at an unspecified state.
-    ///- \c AFTER_PREFLOW_PHASE_1: right after running \c phase1
-    ///- \c AFTER_PREFLOW_PHASE_2: after running \ref phase2()
-    ///
-    enum StatusEnum {
-      AFTER_NOTHING,
-      AFTER_PREFLOW_PHASE_1,      
-      AFTER_PREFLOW_PHASE_2
-    };
-    
-    protected: 
-      FlowEnum flow_prop;
-    StatusEnum status; // Do not needle this flag only if necessary.
-    
-  public: 
-    ///The constructor of the class.
-
-    ///The constructor of the class. 
-    ///\param _G The directed graph the algorithm runs on. 
-    ///\param _s The source node.
-    ///\param _t The target node.
-    ///\param _capacity The capacity of the edges. 
-    ///\param _flow The flow of the edges. 
-    ///Except the graph, all of these parameters can be reset by
-    ///calling \ref setSource, \ref setTarget, \ref setCap and \ref
-    ///setFlow, resp.
-      Preflow(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), 
-	flow_prop(NO_FLOW), status(AFTER_NOTHING) { }
-
-
-                                                                              
-    ///Runs the preflow algorithm.  
-
-    ///Runs the preflow algorithm.
-    ///
-    void run() {
-      phase1(flow_prop);
-      phase2();
-    }
-    
-    ///Runs the preflow algorithm.  
-    
-    ///Runs the preflow algorithm. 
-    ///\pre The starting flow map must be
-    /// - a constant zero flow if \c fp is \c ZERO_FLOW,
-    /// - an arbitrary flow if \c fp is \c GEN_FLOW,
-    /// - an arbitrary preflow if \c fp is \c PRE_FLOW,
-    /// - any map if \c fp is NO_FLOW.
-    ///If the starting flow map is a flow or a preflow then 
-    ///the algorithm terminates faster.
-    void run(FlowEnum fp) {
-      flow_prop=fp;
-      run();
-    }
-      
-    ///Runs the first phase of the preflow algorithm.
-
-    ///The preflow algorithm consists of two phases, this method runs
-    ///the first phase. After the first phase the maximum flow value
-    ///and a minimum value cut can already be computed, though a
-    ///maximum flow is not yet obtained. So after calling this method
-    ///\ref flowValue returns the value of a maximum flow and \ref
-    ///minCut returns a minimum cut.     
-    ///\warning \ref minMinCut and \ref maxMinCut do not give minimum
-    ///value cuts unless calling \ref phase2.  
-    ///\pre The starting flow must be 
-    ///- a constant zero flow if \c fp is \c ZERO_FLOW, 
-    ///- an arbitary flow if \c fp is \c GEN_FLOW, 
-    ///- an arbitary preflow if \c fp is \c PRE_FLOW, 
-    ///- any map if \c fp is NO_FLOW.
-    void phase1(FlowEnum fp)
-    {
-      flow_prop=fp;
-      phase1();
-    }
-
-    
-    ///Runs the first phase of the preflow algorithm.
-
-    ///The preflow algorithm consists of two phases, this method runs
-    ///the first phase. After the first phase the maximum flow value
-    ///and a minimum value cut can already be computed, though a
-    ///maximum flow is not yet obtained. So after calling this method
-    ///\ref flowValue returns the value of a maximum flow and \ref
-    ///minCut returns a minimum cut.
-    ///\warning \ref minCut(), \ref minMinCut() and \ref maxMinCut() do not
-    ///give minimum value cuts unless calling \ref phase2().
-    void phase1()
-    {
-      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
-
-      VecNode first(n, INVALID);
-      NNMap next(*g, INVALID);
-
-      NNMap left(*g, INVALID);
-      NNMap right(*g, INVALID);
-      VecNode level_list(n,INVALID);
-      //List of the nodes in level i<n, set to n.
-
-      preflowPreproc(first, next, level_list, left, right);
-
-      //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 ( first[b]==INVALID ) --b;
-	else {
-	  end=false;
-	  Node w=first[b];
-	  first[b]=next[w];
-	  int newlevel=push(w, next, first);
-	  if ( excess[w] > 0 ) relabel(w, newlevel, first, next, 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;
-	    }
-	  }
-	}
-      }
-      flow_prop=PRE_FLOW;
-      status=AFTER_PREFLOW_PHASE_1;
-    }
-    // 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.
-
-
-    ///Runs the second phase of the preflow algorithm.
-
-    ///The preflow algorithm consists of two phases, this method runs
-    ///the second phase. After calling \ref phase1 and then \ref
-    ///phase2, \ref flow contains a maximum flow, \ref flowValue
-    ///returns the value of a maximum flow, \ref minCut returns a
-    ///minimum cut, while the methods \ref minMinCut and \ref
-    ///maxMinCut return the inclusionwise minimum and maximum cuts of
-    ///minimum value, resp.  \pre \ref phase1 must be called before.
-    void phase2()
-    {
-
-      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
-
-    
-      VecNode first(n, INVALID);
-      NNMap next(*g, INVALID); 
-      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;
-
-	for(InEdgeIt e(*g,v); e!=INVALID; ++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 ) {
-	      next.set(u,first[l]);
-	      first[l]=u;
-	    }
-	  }
-	}
-
-	for(OutEdgeIt e(*g,v); e!=INVALID; ++e) {
-	  if ( 0 >= (*flow)[e] ) continue;
-	  Node u=g->head(e);
-	  if ( level[u] >= n ) {
-	    bfs_queue.push(u);
-	    level.set(u, l);
-	    if ( excess[u] > 0 ) {
-	      next.set(u,first[l]);
-	      first[l]=u;
-	    }
-	  }
-	}
-      }
-      b=n-2;
-
-      while ( true ) {
-
-	if ( b == 0 ) break;
-	if ( first[b]==INVALID ) --b;
-	else {
-	  Node w=first[b];
-	  first[b]=next[w];
-	  int newlevel=push(w,next, first);
-	  
-	  //relabel
-	  if ( excess[w] > 0 ) {
-	    level.set(w,++newlevel);
-	    next.set(w,first[newlevel]);
-	    first[newlevel]=w;
-	    b=newlevel;
-	  }
-	} 
-      } // while(true)
-      flow_prop=GEN_FLOW;
-      status=AFTER_PREFLOW_PHASE_2;
-    }
-
-    /// Returns the value of the maximum flow.
-
-    /// Returns the value of the maximum flow by returning the excess
-    /// of the target node \c t. This value equals to the value of
-    /// the maximum flow already after running \ref phase1.
-    Num flowValue() const {
-      return excess[t];
-    }
-
-
-    ///Returns a minimum value cut.
-
-    ///Sets \c M to the characteristic vector of a minimum value
-    ///cut. This method can be called both after running \ref
-    ///phase1 and \ref phase2. It is much faster after
-    ///\ref phase1.  \pre M should be a bool-valued node-map. \pre
-    ///If \ref minCut() is called after \ref phase2() then M should
-    ///be initialized to false.
-    template<typename _CutMap>
-    void minCut(_CutMap& M) const {
-      switch ( status ) {
-	case AFTER_PREFLOW_PHASE_1:
-	for(NodeIt v(*g); v!=INVALID; ++v) {
-	  if (level[v] < n) {
-	    M.set(v, false);
-	  } else {
-	    M.set(v, true);
-	  }
-	}
-	break;
-	case AFTER_PREFLOW_PHASE_2:
-	minMinCut(M);
-	break;
-	case AFTER_NOTHING:
-	break;
-      }
-    }
-
-    ///Returns the inclusionwise minimum of the minimum value cuts.
-
-    ///Sets \c M to the characteristic vector of the minimum value cut
-    ///which is inclusionwise minimum. It is computed by processing a
-    ///bfs from the source node \c s in the residual graph.  \pre M
-    ///should be a node map of bools initialized to false.  \pre \ref
-    ///phase2 should already be run.
-    template<typename _CutMap>
-    void minMinCut(_CutMap& M) const {
-
-      std::queue<Node> queue;
-      M.set(s,true);
-      queue.push(s);
-      
-      while (!queue.empty()) {
-	Node w=queue.front();
-	queue.pop();
-	
-	for(OutEdgeIt e(*g,w) ; e!=INVALID; ++e) {
-	  Node v=g->head(e);
-	  if (!M[v] && (*flow)[e] < (*capacity)[e] ) {
-	    queue.push(v);
-	    M.set(v, true);
-	  }
-	}
-	
-	for(InEdgeIt e(*g,w) ; e!=INVALID; ++e) {
-	  Node v=g->tail(e);
-	  if (!M[v] && (*flow)[e] > 0 ) {
-	    queue.push(v);
-	    M.set(v, true);
-	  }
-	}
-      }
-    }
-    
-    ///Returns the inclusionwise maximum of the minimum value cuts.
-
-    ///Sets \c M to the characteristic vector of the minimum value cut
-    ///which is inclusionwise maximum. It is computed by processing a
-    ///backward bfs from the target node \c t in the residual graph.
-    ///\pre \ref phase2() or run() should already be run.
-    template<typename _CutMap>
-    void maxMinCut(_CutMap& M) const {
-
-      for(NodeIt v(*g) ; v!=INVALID; ++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();
-
-	for(InEdgeIt e(*g,w) ; e!=INVALID; ++e) {
-	  Node v=g->tail(e);
-	  if (M[v] && (*flow)[e] < (*capacity)[e] ) {
-	    queue.push(v);
-	    M.set(v, false);
-	  }
-	}
-
-	for(OutEdgeIt e(*g,w) ; e!=INVALID; ++e) {
-	  Node v=g->head(e);
-	  if (M[v] && (*flow)[e] > 0 ) {
-	    queue.push(v);
-	    M.set(v, false);
-	  }
-	}
-      }
-    }
-
-    ///Sets the source node to \c _s.
-
-    ///Sets the source node to \c _s.
-    /// 
-    void setSource(Node _s) { 
-      s=_s; 
-      if ( flow_prop != ZERO_FLOW ) flow_prop=NO_FLOW;
-      status=AFTER_NOTHING; 
-    }
-
-    ///Sets the target node to \c _t.
-
-    ///Sets the target node to \c _t.
-    ///
-    void setTarget(Node _t) { 
-      t=_t; 
-      if ( flow_prop == GEN_FLOW ) flow_prop=PRE_FLOW;
-      status=AFTER_NOTHING; 
-    }
-
-    /// Sets the edge map of the capacities to _cap.
-
-    /// Sets the edge map of the capacities to _cap.
-    /// 
-    void setCap(const CapMap& _cap) { 
-      capacity=&_cap; 
-      status=AFTER_NOTHING; 
-    }
-
-    /// Sets the edge map of the flows to _flow.
-
-    /// Sets the edge map of the flows to _flow.
-    /// 
-    void setFlow(FlowMap& _flow) { 
-      flow=&_flow; 
-      flow_prop=NO_FLOW;
-      status=AFTER_NOTHING; 
-    }
-
-
-  private:
-
-    int push(Node w, NNMap& next, VecNode& first) {
-
-      int lev=level[w];
-      Num exc=excess[w];
-      int newlevel=n;       //bound on the next level of w
-
-      for(OutEdgeIt e(*g,w) ; e!=INVALID; ++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 ) {
-	    next.set(v,first[level[v]]);
-	    first[level[v]]=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 ) {
-	for(InEdgeIt e(*g,w) ; e!=INVALID; ++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 ) {
-	      next.set(v,first[level[v]]);
-	      first[level[v]]=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(VecNode& first, NNMap& next, 
-			VecNode& level_list, NNMap& left, NNMap& right)
-    {
-      for(NodeIt v(*g); v!=INVALID; ++v) level.set(v,n);
-      std::queue<Node> bfs_queue;
-      
-      if ( flow_prop == GEN_FLOW || flow_prop == PRE_FLOW ) {
-	//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;
-	  
-	  for(InEdgeIt e(*g,v) ; e!=INVALID; ++e) {
-	    if ( (*capacity)[e] <= (*flow)[e] ) continue;
-	    Node w=g->tail(e);
-	    if ( level[w] == n && w != s ) {
-	      bfs_queue.push(w);
-	      Node z=level_list[l];
-	      if ( z!=INVALID ) left.set(z,w);
-	      right.set(w,z);
-	      level_list[l]=w;
-	      level.set(w, l);
-	    }
-	  }
-	  
-	  for(OutEdgeIt e(*g,v) ; e!=INVALID; ++e) {
-	    if ( 0 >= (*flow)[e] ) continue;
-	    Node w=g->head(e);
-	    if ( level[w] == n && w != s ) {
-	      bfs_queue.push(w);
-	      Node z=level_list[l];
-	      if ( z!=INVALID ) left.set(z,w);
-	      right.set(w,z);
-	      level_list[l]=w;
-	      level.set(w, l);
-	    }
-	  }
-	} //while
-      } //if
-
-
-      switch (flow_prop) {
-	case NO_FLOW:  
-	for(EdgeIt e(*g); e!=INVALID; ++e) flow->set(e,0);
-	case ZERO_FLOW:
-	for(NodeIt v(*g); v!=INVALID; ++v) excess.set(v,0);
-	
-	//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;
-	  
-	  for(InEdgeIt e(*g,v) ; e!=INVALID; ++e) {
-	    Node w=g->tail(e);
-	    if ( level[w] == n && w != s ) {
-	      bfs_queue.push(w);
-	      Node z=level_list[l];
-	      if ( z!=INVALID ) left.set(z,w);
-	      right.set(w,z);
-	      level_list[l]=w;
-	      level.set(w, l);
-	    }
-	  }
-	}
-	
-	//the starting flow
-	for(OutEdgeIt e(*g,s) ; e!=INVALID; ++e) {
-	  Num c=(*capacity)[e];
-	  if ( c <= 0 ) continue;
-	  Node w=g->head(e);
-	  if ( level[w] < n ) {
-	    if ( excess[w] <= 0 && w!=t ) { //putting into the stack
-	      next.set(w,first[level[w]]);
-	      first[level[w]]=w;
-	    }
-	    flow->set(e, c);
-	    excess.set(w, excess[w]+c);
-	  }
-	}
-	break;
-
-	case GEN_FLOW:
-	for(NodeIt v(*g); v!=INVALID; ++v) excess.set(v,0);
-	{
-	  Num exc=0;
-	  for(InEdgeIt e(*g,t) ; e!=INVALID; ++e) exc+=(*flow)[e];
-	  for(OutEdgeIt e(*g,t) ; e!=INVALID; ++e) exc-=(*flow)[e];
-	  excess.set(t,exc);
-	}
-
-	//the starting flow
-	for(OutEdgeIt e(*g,s); e!=INVALID; ++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 ) { //putting into the stack
-	      next.set(w,first[level[w]]);
-	      first[level[w]]=w;
-	    }   
-	    flow->set(e, (*capacity)[e]);
-	    excess.set(w, excess[w]+rem);
-	  }
-	}
-	
-	for(InEdgeIt e(*g,s); e!=INVALID; ++e) {
-	  if ( (*flow)[e] <= 0 ) continue;
-	  Node w=g->tail(e);
-	  if ( level[w] < n ) {
-	    if ( excess[w] <= 0 && w!=t ) {
-	      next.set(w,first[level[w]]);
-	      first[level[w]]=w;
-	    }  
-	    excess.set(w, excess[w]+(*flow)[e]);
-	    flow->set(e, 0);
-	  }
-	}
-	break;
-
-	case PRE_FLOW:	
-	//the starting flow
-	for(OutEdgeIt e(*g,s) ; e!=INVALID; ++e) {
-	  Num rem=(*capacity)[e]-(*flow)[e];
-	  if ( rem <= 0 ) continue;
-	  Node w=g->head(e);
-	  if ( level[w] < n ) flow->set(e, (*capacity)[e]);
-	}
-	
-	for(InEdgeIt e(*g,s) ; e!=INVALID; ++e) {
-	  if ( (*flow)[e] <= 0 ) continue;
-	  Node w=g->tail(e);
-	  if ( level[w] < n ) flow->set(e, 0);
-	}
-	
-	//computing the excess
-	for(NodeIt w(*g); w!=INVALID; ++w) {
-	  Num exc=0;
-	  for(InEdgeIt e(*g,w); e!=INVALID; ++e) exc+=(*flow)[e];
-	  for(OutEdgeIt e(*g,w); e!=INVALID; ++e) exc-=(*flow)[e];
-	  excess.set(w,exc);
-	  
-	  //putting the active nodes into the stack
-	  int lev=level[w];
-	    if ( exc > 0 && lev < n && Node(w) != t ) {
-	      next.set(w,first[lev]);
-	      first[lev]=w;
-	    }
-	}
-	break;
-      } //switch
-    } //preflowPreproc
-
-
-    void relabel(Node w, int newlevel, VecNode& first, NNMap& next, 
-		 VecNode& level_list, NNMap& left,
-		 NNMap& right, int& b, int& k, bool what_heur )
-    {
-
-      int lev=level[w];
-
-      Node right_n=right[w];
-      Node left_n=left[w];
-
-      //unlacing starts
-      if ( right_n!=INVALID ) {
-	if ( left_n!=INVALID ) {
-	  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 ( left_n!=INVALID ) {
-	  right.set(left_n, INVALID);
-	} else {
-	  level_list[lev]=INVALID;
-	}
-      }
-      //unlacing ends
-
-      if ( level_list[lev]==INVALID ) {
-
-	//gapping starts
-	for (int i=lev; i!=k ; ) {
-	  Node v=level_list[++i];
-	  while ( v!=INVALID ) {
-	    level.set(v,n);
-	    v=right[v];
-	  }
-	  level_list[i]=INVALID;
-	  if ( !what_heur ) first[i]=INVALID;
-	}
-
-	level.set(w,n);
-	b=lev-1;
-	k=b;
-	//gapping ends
-
-      } else {
-
-	if ( newlevel == n ) level.set(w,n);
-	else {
-	  level.set(w,++newlevel);
-	  next.set(w,first[newlevel]);
-	  first[newlevel]=w;
-	  if ( what_heur ) b=newlevel;
-	  if ( k < newlevel ) ++k;      //now k=newlevel
-	  Node z=level_list[newlevel];
-	  if ( z!=INVALID ) left.set(z,w);
-	  right.set(w,z);
-	  left.set(w,INVALID);
-	  level_list[newlevel]=w;
-	}
-      }
-    } //relabel
-
-  }; 
-} //namespace hugo
-
-#endif //HUGO_PREFLOW_H
-
-
-
-