Method SteelMill

examples/steel-mill.cpp:191–293

Actual model

  /// Actual model
  SteelMill(const SteelMillOptions& opt)
    : // Initialize instance data
      IntMinimizeScript(opt),
      capacities(opt.capacities()), ncapacities(opt.ncapacities()),
      maxcapacity(opt.maxcapacity()), loss(opt.loss()),
      ncolors(opt.ncolors()), orders(opt.orders()),
      norders(opt.size()), nslabs(opt.size()),
      // Initialize problem variables
      slab(*this, norders, 0,nslabs-1),
      slabload(*this, nslabs, 0,45),
      slabcost(*this, nslabs, 0, Int::Limits::max),
      total_cost(*this, 0, Int::Limits::max)
  {
    // Boolean variables for slab[o]==s
    BoolVarArgs boolslab(norders*nslabs);
    for (unsigned int i = 0; i < norders; ++i) {
      BoolVarArgs tmp(nslabs);
      for (int j = nslabs; j--; ) {
        boolslab[j + i*nslabs] = tmp[j] = BoolVar(*this, 0, 1);
      }
      channel(*this, tmp, slab[i]);
    }

    // Packing constraints
    for (unsigned int s = 0; s < nslabs; ++s) {
      IntArgs c(norders);
      BoolVarArgs x(norders);
      for (int i = norders; i--; ) {
        c[i] = orders[i][order_weight];
        x[i] = boolslab[s + i*nslabs];
      }
      linear(*this, c, x, IRT_EQ, slabload[s]);
    }
    // Redundant packing constraint
    int totalweight = 0;
    for (unsigned int i = norders; i-- ; )
       totalweight += orders[i][order_weight] ;
    linear(*this, slabload, IRT_EQ, totalweight);


    // Color constraints
    IntArgs nofcolor(ncolors);
    for (int c = ncolors; c--; ) {
      nofcolor[c] = 0;
      for (int o = norders; o--; ) {
        if (orders[o][order_color] == c) nofcolor[c] += 1;
      }
    }
    BoolVar f(*this, 0, 0);
    for (unsigned int s = 0; s < nslabs; ++s) {
      BoolVarArgs hascolor(ncolors);
      for (int c = ncolors; c--; ) {
        if (nofcolor[c]) {
          BoolVarArgs hasc(nofcolor[c]);
          int pos = 0;
          for (int o = norders; o--; ) {
            if (orders[o][order_color] == c)
              hasc[pos++] = boolslab[s + o*nslabs];