 /* 
  * Copyright 1997, Regents of the University of Minnesota 
  * 
  * fm.c 
  * 
  * This file contains code that implements the edge-based FM refinement 
  * 
  * Started 7/23/97 
  * George 
  * 
  * $Id: fm.c,v 1.1 1998/11/27 17:59:14 karypis Exp $ 
  */ 

 #include <metis.h> 


 /************************************************************************* 
 * This function performs an edge-based FM refinement 
 **************************************************************************/ 
 void FM_2WayEdgeRefine(CtrlType *ctrl, GraphType *graph, long *tpwgts, long npasses) 
 { 
   long i, ii, j, k, kwgt, nvtxs, nbnd, nswaps, from, to, pass, me, limit, tmp; 
   idxtype *xadj, *vwgt, *adjncy, *adjwgt, *where, *id, *ed, *bndptr, *bndind, *pwgts; 
   idxtype *moved, *swaps, *perm; 
   PQueueType parts[2]; 
   long higain, oldgain, mincut, mindiff, origdiff, initcut, newcut, mincutorder, avgvwgt; 

   nvtxs = graph->nvtxs; 
   xadj = graph->xadj; 
   vwgt = graph->vwgt; 
   adjncy = graph->adjncy; 
   adjwgt = graph->adjwgt; 
   where = graph->where; 
   id = graph->id; 
   ed = graph->ed; 
   pwgts = graph->pwgts; 
   bndptr = graph->bndptr; 
   bndind = graph->bndind; 

   moved = idxwspacemalloc(ctrl, nvtxs); 
   swaps = idxwspacemalloc(ctrl, nvtxs); 
   perm = idxwspacemalloc(ctrl, nvtxs); 

   limit = amin(amax(0.01*nvtxs, 15), 100); 
   avgvwgt = amin((pwgts[0]+pwgts[1])/20, 2*(pwgts[0]+pwgts[1])/nvtxs); 

   tmp = graph->adjwgtsum[idxamax(nvtxs, graph->adjwgtsum)]; 
   PQueueInit(ctrl, &parts[0], nvtxs, tmp); 
   PQueueInit(ctrl, &parts[1], nvtxs, tmp); 

   IFSET(ctrl->dbglvl, DBG_REFINE,  
      printf("Partitions: [%6ld %6ld] T[%6ld %6ld], Nv-Nb[%6ld %6ld]. ICut: %6ld\n", 
              pwgts[0], pwgts[1], tpwgts[0], tpwgts[1], graph->nvtxs, graph->nbnd, graph->mincut)); 

   origdiff = abs(tpwgts[0]-pwgts[0]); 
   idxset(nvtxs, -1, moved); 
   for (pass=0; pass<npasses; pass++) { /* Do a number of passes */ 
     PQueueReset(&parts[0]); 
     PQueueReset(&parts[1]); 

     mincutorder = -1; 
     newcut = mincut = initcut = graph->mincut; 
     mindiff = abs(tpwgts[0]-pwgts[0]); 

     ASSERT(ComputeCut(graph, where) == graph->mincut); 
     ASSERT(CheckBnd(graph)); 

     /* Insert boundary nodes in the priority queues */ 
     nbnd = graph->nbnd; 
     RandomPermute(nbnd, perm, 1); 
     for (ii=0; ii<nbnd; ii++) { 
       i = perm[ii]; 
       ASSERT(ed[bndind[i]] > 0 || id[bndind[i]] == 0); 
       ASSERT(bndptr[bndind[i]] != -1); 
       PQueueInsert(&parts[where[bndind[i]]], bndind[i], ed[bndind[i]]-id[bndind[i]]); 
     } 

     for (nswaps=0; nswaps<nvtxs; nswaps++) { 
       from = (tpwgts[0]-pwgts[0] < tpwgts[1]-pwgts[1] ? 0 : 1); 
       to = (from+1)%2; 

       if ((higain = PQueueGetMax(&parts[from])) == -1) 
         break; 
       ASSERT(bndptr[higain] != -1); 

       newcut -= (ed[higain]-id[higain]); 
       INC_DEC(pwgts[to], pwgts[from], vwgt[higain]); 

       if ((newcut < mincut && abs(tpwgts[0]-pwgts[0]) <= origdiff+avgvwgt) ||  
           (newcut == mincut && abs(tpwgts[0]-pwgts[0]) < mindiff)) { 
         mincut = newcut; 
         mindiff = abs(tpwgts[0]-pwgts[0]); 
         mincutorder = nswaps; 
       } 
       else if (nswaps-mincutorder > limit) { /* We hit the limit, undo last move */ 
         newcut += (ed[higain]-id[higain]); 
         INC_DEC(pwgts[from], pwgts[to], vwgt[higain]); 
         break; 
       } 

       where[higain] = to; 
       moved[higain] = nswaps; 
       swaps[nswaps] = higain; 

       IFSET(ctrl->dbglvl, DBG_MOVEINFO,  
         printf("Moved %6ld from %ld. [%3ld %3ld] %5ld [%4ld %4ld]\n", higain, from, ed[higain]-id[higain], vwgt[higain], newcut, pwgts[0], pwgts[1])); 

       /************************************************************** 
       * Update the id[i]/ed[i] values of the affected nodes 
       ***************************************************************/ 
       SWAP(id[higain], ed[higain], tmp); 
       if (ed[higain] == 0 && xadj[higain] < xadj[higain+1])  
         BNDDelete(nbnd, bndind,  bndptr, higain); 

       for (j=xadj[higain]; j<xadj[higain+1]; j++) { 
         k = adjncy[j]; 
         oldgain = ed[k]-id[k]; 

         kwgt = (to == where[k] ? adjwgt[j] : -adjwgt[j]); 
         INC_DEC(id[k], ed[k], kwgt); 

         /* Update its boundary information and queue position */ 
         if (bndptr[k] != -1) { /* If k was a boundary vertex */ 
           if (ed[k] == 0) { /* Not a boundary vertex any more */ 
             BNDDelete(nbnd, bndind, bndptr, k); 
             if (moved[k] == -1)  /* Remove it if in the queues */ 
               PQueueDelete(&parts[where[k]], k, oldgain); 
           } 
           else { /* If it has not been moved, update its position in the queue */ 
             if (moved[k] == -1) 
               PQueueUpdate(&parts[where[k]], k, oldgain, ed[k]-id[k]); 
           } 
         } 
         else { 
           if (ed[k] > 0) {  /* It will now become a boundary vertex */ 
             BNDInsert(nbnd, bndind, bndptr, k); 
             if (moved[k] == -1)  
               PQueueInsert(&parts[where[k]], k, ed[k]-id[k]); 
           } 
         } 
       } 

     } 


     /**************************************************************** 
     * Roll back computations 
     *****************************************************************/ 
     for (i=0; i<nswaps; i++) 
       moved[swaps[i]] = -1;  /* reset moved array */ 
     for (nswaps--; nswaps>mincutorder; nswaps--) { 
       higain = swaps[nswaps]; 

       to = where[higain] = (where[higain]+1)%2; 
       SWAP(id[higain], ed[higain], tmp); 
       if (ed[higain] == 0 && bndptr[higain] != -1 && xadj[higain] < xadj[higain+1]) 
         BNDDelete(nbnd, bndind,  bndptr, higain); 
       else if (ed[higain] > 0 && bndptr[higain] == -1) 
         BNDInsert(nbnd, bndind,  bndptr, higain); 

       INC_DEC(pwgts[to], pwgts[(to+1)%2], vwgt[higain]); 
       for (j=xadj[higain]; j<xadj[higain+1]; j++) { 
         k = adjncy[j]; 

         kwgt = (to == where[k] ? adjwgt[j] : -adjwgt[j]); 
         INC_DEC(id[k], ed[k], kwgt); 

         if (bndptr[k] != -1 && ed[k] == 0) 
           BNDDelete(nbnd, bndind, bndptr, k); 
         if (bndptr[k] == -1 && ed[k] > 0) 
           BNDInsert(nbnd, bndind, bndptr, k); 
       } 
     } 

     IFSET(ctrl->dbglvl, DBG_REFINE,  
       printf("\tMinimum cut: %6ld at %5ld, PWGTS: [%6ld %6ld], NBND: %6ld\n", mincut, mincutorder, pwgts[0], pwgts[1], nbnd)); 

     graph->mincut = mincut; 
     graph->nbnd = nbnd; 

     if (mincutorder == -1 || mincut == initcut) 
       break; 
   } 

   PQueueFree(ctrl, &parts[0]); 
   PQueueFree(ctrl, &parts[1]); 

   idxwspacefree(ctrl, nvtxs); 
   idxwspacefree(ctrl, nvtxs); 
   idxwspacefree(ctrl, nvtxs); 

 } 


