Method MultiBinPacking

examples/multi-bin-packing.cpp:130–195

Actual model

  };
  /// Actual model
  MultiBinPacking(const InstanceOptions& opt)
    : Script(opt), spec(opt.instance()),
      bin(*this, spec.items(), 0, spec.bins()-1),
      load(*this, spec.bins()*spec.dimension(), 0, Int::Limits::max)
  {

    switch (opt.model()) {
    case MODEL_SINGLE:
      {
        // Constrain load variables in every dimension
        for (int k=0; k<spec.dimension(); k++)
          for (int j=0; j<spec.bins(); j++)
            rel(*this, load[j*spec.dimension()+k] <= spec.capacity(k));

        // Post bin-packing constraint for each dimension
        for (int k=0; k<spec.dimension(); k++) {
          IntVarArgs l(spec.bins());
          for (int j=0; j<spec.bins(); j++)
            l[j]=load[j*spec.dimension()+k];
          IntArgs s(spec.items());
          for (int i=0; i<spec.items(); i++)
            s[i]=spec.size(i,k);

          binpacking(*this, l, bin, s);
        }
      }
      break;
    case MODEL_MULTI:
      {
        // Every bin has the same capacity for a given dimension
        IntArgs c(spec.dimension());
        for (int k=0; k<spec.dimension(); k++)
          c[k] = spec.capacity(k);

        // Item size for each dimension
        IntArgs s(spec.items()*spec.dimension());
        for (int i=0; i<spec.items(); i++)
          for (int k=0; k<spec.dimension(); k++)
            s[i*spec.dimension()+k] = spec.size(i,k);

        // Post multidimensional binpacking constraint
        IntSet mc = binpacking(*this, spec.dimension(), load, bin, s, c);

        // Symmetry breaking
        if (opt.symmetry() == SYMMETRY_MAX_CONFLICT) {
          // Use a maximal conflict set by assigning items to fixed bins
          IntVarArgs bc(mc.size());
          int j=0;
          for (IntSetValues i(mc); i(); ++i)
            bc[j++] = bin[i.val()];
          assign(*this, bc, INT_ASSIGN_MIN());
        }
      }
      break;
    }

    // Branching strategy
    switch (opt.branching()) {