Method Domino

examples/domino.cpp:88–189

Actual model

  /// Actual model
  Domino(const SizeOptions& opt)
    : Script(opt),
      spec(specs[opt.size()]),
      width(spec[0]), height(spec[1]),
      x(*this, (width+1)*height, 0, 28) {
    spec+=2; // skip board size information

    // Copy spec information to the board
    IntArgs board((width+1)*height);
    for (int i=0; i<width; i++)
      for (int j=0; j<height; j++)
        board[j*(width+1)+i] = spec[j*width+i];

    // Initialize the separator column in the board
    for (int i=0; i<height; i++) {
      board[i*(width+1)+8] = -1;
      rel(*this, x[i*(width+1)+8]==28);
    }

    // Variables representing the coordinates of the first
    // and second half of a domino piece
    IntVarArgs p1(*this, 28, 0, (width+1)*height-1);
    IntVarArgs p2(*this, 28, 0, (width+1)*height-1);


    if (opt.propagation() == PROP_ELEMENT) {
      int dominoCount = 0;

      int possibleDiffsA[] = {1, width+1};
      IntSet possibleDiffs(possibleDiffsA, 2);

      for (int i=0; i<=6; i++)
        for (int j=i; j<=6; j++) {

          // The two coordinates must be adjacent.
          // I.e., they may differ by 1 or by the width.
          // The separator column makes sure that a field
          // at the right border is not adjacent to the first field
          // in the next row.
          IntVar diff(*this, possibleDiffs);
          abs(*this, expr(*this, p1[dominoCount]-p2[dominoCount]),
              diff, IPL_DOM);

          // If the piece is symmetrical, order the locations
          if (i == j)
            rel(*this, p1[dominoCount], IRT_LE, p2[dominoCount]);

          // Link the current piece to the board
          element(*this, board, p1[dominoCount], i);
          element(*this, board, p2[dominoCount], j);

          // Link the current piece to the array where its
          // number is stored.
          element(*this, x, p1[dominoCount], dominoCount);
          element(*this, x, p2[dominoCount], dominoCount);
          dominoCount++;
        }
    } else {