source: lemon-0.x/src/work/jacint/preflow_res.h @ 1169:8b06fbd5712c

// -*- C++ -*-
//The same as preflow.h, using ResGraphWrapper
#ifndef LEMON_PREFLOW_RES_H
#define LEMON_PREFLOW_RES_H

#define H0 20
#define H1 1

#include <vector>
#include <queue>
#include <graph_wrapper.h>

#include<iostream>

namespace lemon {

  template <typename Graph, typename T, 
            typename CapMap=typename Graph::template EdgeMap<T>, 
            typename FlowMap=typename Graph::template EdgeMap<T> >
  class PreflowRes {
    
    typedef typename Graph::Node Node;
    typedef typename Graph::Edge Edge;
    typedef typename Graph::NodeIt NodeIt;
    typedef typename Graph::OutEdgeIt OutEdgeIt;
    typedef typename Graph::InEdgeIt InEdgeIt;
    
    const Graph& G;
    Node s;
    Node t;
    const CapMap& capacity;  
    FlowMap& flow;
    T value;
    bool constzero;

    typedef ResGraphWrapper<const Graph, T, CapMap, FlowMap> ResGW;
    typedef typename ResGW::OutEdgeIt ResOutEdgeIt;
    typedef typename ResGW::InEdgeIt ResInEdgeIt;
    typedef typename ResGW::Edge ResEdge;
 
  public:
    PreflowRes(Graph& _G, Node _s, Node _t, CapMap& _capacity, 
            FlowMap& _flow, bool _constzero ) :
      G(_G), s(_s), t(_t), capacity(_capacity), flow(_flow), constzero(_constzero) {}
    
    
    void run() {

      ResGW res_graph(G, capacity, flow);

      value=0;                //for the subsequent runs

      bool phase=0;        //phase 0 is the 1st phase, phase 1 is the 2nd
      int n=G.nodeNum(); 
      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)
      bool what_heur=1;       
      /*
        what_heur 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 relabel=0;
      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
      
      typename Graph::template NodeMap<int> level(G,n);      
      typename Graph::template NodeMap<T> excess(G); 

      std::vector<Node> active(n-1,INVALID);
      typename Graph::template NodeMap<Node> next(G,INVALID);
      //Stack of the active nodes in level i < n.
      //We use it in both phases.

      typename Graph::template NodeMap<Node> left(G,INVALID);
      typename Graph::template NodeMap<Node> right(G,INVALID);
      std::vector<Node> level_list(n,INVALID);
      /*
        List of the nodes in level i<n.
      */


      /*
        Reverse_bfs from t in the residual graph, 
        to find the starting level.
      */
      level.set(t,0);
      std::queue<Node> bfs_queue;
      bfs_queue.push(t);
      
      while (!bfs_queue.empty()) {
        
        Node v=bfs_queue.front();       
        bfs_queue.pop();
        int l=level[v]+1;
        
        ResInEdgeIt e;
        for(res_graph.first(e,v); res_graph.valid(e); 
            res_graph.next(e)) {
          Node w=res_graph.source(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);
          }
        }
      }
      
        
      if ( !constzero ) {
        /*
          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 ) {
            next.set(v,active[lev]);
            active[lev]=v;
          }
        }
      }
     


      //the starting flow
      ResOutEdgeIt e;
      for(res_graph.first(e,s); res_graph.valid(e); 
          res_graph.next(e)) {
          Node w=res_graph.target(e);
          if ( level[w] < n ) {   
            if ( excess[w] == 0 && w!=t ) {
              next.set(w,active[level[w]]);
              active[level[w]]=w;
            }
            T rem=res_graph.resCap(e);
            excess.set(w, excess[w]+rem);
            res_graph.augment(e, rem ); 
          }
      }
        

      /* 
         End of preprocessing 
      */



      /*
        Push/relabel on the highest level active nodes.
      */        
      while ( true ) {
        
        if ( b == 0 ) {
          if ( phase ) break;
          
          if ( !what_heur && !end && k > 0 ) {
            b=k;
            end=true;
          } else {
            phase=1;
            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;
              
              ResInEdgeIt e;
              for(res_graph.first(e,v); 
                  res_graph.valid(e); res_graph.next(e)) {
                Node u=res_graph.source(e);
                if ( level[u] >= n ) { 
                  bfs_queue.push(u);
                  level.set(u, l);
                  if ( excess[u] > 0 ) {
                    next.set(u,active[l]);
                    active[l]=u;
                  }
                }
              }
            
            }
            b=n-2;
          }
            
        }
          
          
        if ( !G.valid(active[b]) ) --b; 
        else {
          end=false;  

          Node w=active[b];
          active[b]=next[w];
          int lev=level[w];
          T exc=excess[w];
          int newlevel=n;       //bound on the next level of w
          
          ResOutEdgeIt e;
          for(res_graph.first(e,w); res_graph.valid(e); res_graph.next(e)) {
            
            Node v=res_graph.target(e);            
            if( lev > level[v] ) {      
              /*Push is allowed now*/
              
              if ( excess[v]==0 && v!=t && v!=s ) {
                int lev_v=level[v];
                next.set(v,active[lev_v]);
                active[lev_v]=v;
              }
              
              T remcap=res_graph.resCap(e);
              
              if ( remcap >= exc ) {       
                /*A nonsaturating push.*/
                res_graph.augment(e, exc);
                excess.set(v, excess[v]+exc);
                exc=0;
                break; 
                
              } else { 
                /*A saturating push.*/
                
                res_graph.augment(e, remcap);
                excess.set(v, excess[v]+remcap);
                exc-=remcap;
              }
            } else if ( newlevel > level[v] ){
              newlevel = level[v];
            }       
            
          }

        excess.set(w, exc);
         
        /*
          Relabel
        */
        

        if ( exc > 0 ) {
          //now 'lev' is the old level of w
        
          if ( phase ) {
            level.set(w,++newlevel);
            next.set(w,active[newlevel]);
            active[newlevel]=w;
            b=newlevel;
          } else {
            //unlacing starts
            Node right_n=right[w];
            Node left_n=left[w];

            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 ) active[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,active[newlevel]);
                active[newlevel]=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; 
            if ( relabel >= heur ) {
              relabel=0;
              if ( what_heur ) {
                what_heur=0;
                heur=heur0;
                end=false;
              } else {
                what_heur=1;
                heur=heur1;
                b=k; 
              }
            }
          } //phase 0
          
          
        } // if ( exc > 0 )
          
        
        }  // if stack[b] is nonempty
        
      } // while(true)


      value = excess[t];
      /*Max flow value.*/
     
    } //void run()





    /*
      Returns the maximum value of a flow.
     */

    T flowValue() {
      return value;
    }


    FlowMap Flow() {
      return flow;
      }


    
    void Flow(FlowMap& _flow ) {
      NodeIt v;
      for(G.first(v) ; G.valid(v); G.next(v))
        _flow.set(v,flow[v]);
    }



    /*
      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.target(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.source(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) {
    
      std::queue<Node> queue;
      
      M.set(t,true);        
      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.source(e);
          if (!M[v] && flow[e] < capacity[e] ) {
            queue.push(v);
            M.set(v, true);
          }
        }
        
        OutEdgeIt f;
        for(G.first(f,w) ; G.valid(f); G.next(f)) {
          Node v=G.target(f);
          if (!M[v] && flow[f] > 0 ) {
            queue.push(v);
            M.set(v, true);
          }
        }
      }

      NodeIt v;
      for(G.first(v) ; G.valid(v); G.next(v)) {
        M.set(v, !M[v]);
      }

    }



    template<typename CutMap>
    void minCut(CutMap& M) {
      minMinCut(M);
    }

    
    
    void resetTarget (Node _t) {t=_t;}
    void resetSource (Node _s) {s=_s;}
   
    void resetCap (CapMap _cap) {capacity=_cap;}

    void resetFlow (FlowMap _flow, bool _constzero) {
      flow=_flow;
      constzero=_constzero;
    }


  };

} //namespace lemon

#endif //LEMON_PREFLOW_RES_H