// -*- 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()

 T 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>

 namespace hugo {

   template <typename Graph, typename T, 

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

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

   class Preflow {

     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;

     CapMap* capacity;  

     FlowMap* flow;

     int n;      //the number of nodes of G

     typename Graph::template NodeMap<int> level;      

     typename Graph::template NodeMap<T> excess; 

   public:

     enum flowEnum{

       ZERO_FLOW=0,

       GEN_FLOW=1,

       PREFLOW=2

     };

     Preflow(Graph& _G, Node _s, Node _t, 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 ) {

       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)) {

 	    T 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

 	  T 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;

 	}

       }

       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; 

 	    }

 	  }

 	} 

       } 

     }

     void 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)

     }

     //Returns the maximum value of a flow.

     T flowValue() {

       return excess[t];

     }

     //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 (const Node _t) {t=_t;}

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

     void resetCap (const CapMap& _cap) {

       capacity=&_cap;

     }

     void resetFlow (FlowMap& _flow) {

       flow=&_flow;

     }

   private:

     int push(const Node w, VecStack& active) {

       int lev=level[w];

       T 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);

 	  }

 	  T cap=(*capacity)[e];

 	  T flo=(*flow)[e];

 	  T 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);

 	    }

 	    T 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)) 

 	    {

 	      T 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)) 

 	    {

 	      T 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( const Node w, int newlevel, VecStack& active,  

 		  VecNode& level_list, NNMap& left, 

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

       T 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

   };

 } //namespace hugo

 #endif //HUGO_PREFLOW_H