docs: private void intersectionMatrix(int[][] res, ArrayList<int[]> partsx, ArrayList<int[]> partsy, int gridsize) {
      for(int x = 0; x < gridsize; x++) {
        final int[] px = partsx.get(x);
        final int[] rowx = res[x];
        for(int y = 0; y < gridsize; y++) {
          int[] py = partsy.get(y);
          rowx[y] = intersectionSize(px, py);
        }
      }
    }