public Cell getMinPossibleCell(List<Cell> cells) {
		int minPossibles = 9;
		int size = 0;
		int index = -1;
		for (int i = 0; i < cells.size(); i++) {
			Cell cell = cells.get(i);

			if (cell.possibleList == null || cell.value != '.') {
				continue;
			}
			size = cell.possibleList.size();
			if (size < minPossibles) {
				minPossibles = size;
				index = i;
			}
		}
		if (index == -1) {
			return null;
		}
		return cells.get(index);
	}