规则Rules：
标准数独基础上，涂色格等于其左右两侧数字之差，也等于其上下两侧数字之差。如果两侧只有一格则不做计算。
Classic rules applied. Additionally, the colored cell equals to the difference between the numbers on the left and right sides, as well as the difference between the numbers on the top and bottom sides. No necessary for calculate when two sides own one cell.
