private NPuzzleState slideLeft() {
   int[][] copyOfLayout = TwoDArrayUtils.makeCopy(layout);
   swapWithEmpty(copyOfLayout, (int) emptySpace.getX() + 1, (int) emptySpace.getY());
   return new NPuzzleState(copyOfLayout, n);
 }
 private void findCoordinatesOfEmptySpace() {
   emptySpace = TwoDArrayUtils.findValue(layout, EMPTY_SPACE);
 }