void initSets() {
		for (int i = 0; i < 9; i++) {
			HashSet<Integer> vertical = new HashSet<Integer>();
			verticalSets.add(vertical);
			HashSet<Integer> horizontal = new HashSet<Integer>();
			horizontalSets.add(horizontal);
			HashSet<Integer> square = new HashSet<Integer>();
			squareSets.add(square);
		}
	}