Method propagate

gecode/set/int/minmax.hpp:71–129

  template<class View>
  ExecStatus
  MinElement<View>::propagate(Space& home, const ModEventDelta&) {
    //x1 is an element of x0.ub
    //x1 =< smallest element of x0.lb
    //x1 =< x0.cardinialityMin-est largest element of x0.ub
    //(these 2 take care of determined x0)
    //No element in x0 is smaller than x1
    //if x1 is determined, it is part of the ub.

    //Consequently:
    //The domain of x1 is a subset of x0.ub up to the first element in x0.lb.
    //x0 lacks everything smaller than smallest possible x1.

    {
      LubRanges<View> ub(x0);
      GECODE_ME_CHECK(x1.inter_r(home,ub,false));
    }
    GECODE_ME_CHECK(x1.lq(home,x0.glbMin()));
    //if cardMin>lbSize?
    assert(x0.cardMin()>=1);

    {
      /// Compute n-th largest element in x0.lub for n = x0.cardMin()-1
      unsigned int size = 0;
      int maxN = BndSet::MAX_OF_EMPTY;
      for (LubRanges<View> ubr(x0); ubr(); ++ubr, ++size) {}
      Region r;
      int* ub = r.alloc<int>(size*2);
      {
        int i=0;
        for (LubRanges<View> ubr(x0); ubr(); ++ubr, ++i) {
          ub[2*i]   = ubr.min();
          ub[2*i+1] = ubr.max();
        }
      }
      unsigned int x0cm = x0.cardMin()-1;
      for (unsigned int i=size; i--;) {
        unsigned int width = static_cast<unsigned int>(ub[2*i+1]-ub[2*i]+1);
        if (width > x0cm) {
          maxN = static_cast<int>(ub[2*i+1]-x0cm);
          break;
        }
        x0cm -= width;
      }
      GECODE_ME_CHECK(x1.lq(home,maxN));
    }

    GECODE_ME_CHECK( x0.exclude(home,
                                Limits::min, x1.min()-1) );

    if (x1.assigned()) {
      GECODE_ME_CHECK(x0.include(home,x1.val()));
      GECODE_ME_CHECK(x0.exclude(home,
                                 Limits::min, x1.val()-1));
      return home.ES_SUBSUMED(*this);
    }

    return ES_FIX;