text: /*
   * 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 8776 2013-11-14 09:04:48Z roboos $
   */
  
  #include <metis.h>
  
  
  /*************************************************************************
  * This function performs an edge-based FM refinement
  **************************************************************************/
  void FM_2WayEdgeRefine(CtrlType *ctrl, GraphType *graph, int *tpwgts, int npasses)
  {
    int 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];
    int 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: [%6d %6d] T[%6d %6d], Nv-Nb[%6d %6d]. ICut: %6d\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 %6d from %d. [%3d %3d] %5d [%4d %4d]\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: %6d at %5d, PWGTS: [%6d %6d], NBND: %6d\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);
  
  }
  
  
  