奇偶 Odd Even

标准数独基础上，灰色圆圈填奇数（1，3，5，7，9......），灰色方块填偶数（2，4，6，8......）。

Classic rules applied, additionally, grey circle cells should contain odd numbers (1,3,5,7,9......) and grey square cells should contain even numbers (2,4,6,8.....). 

◆有符号的格有确定的候选数，容易找到显性唯一。

Marked cells have affimatory candidates. Naked singles may be find.

◆奇数不在方，偶数不在圆，我们可以藉此观察隐性唯一。

Odd cannot be in squares, Even cannot be in circles, so we may find Hidden singles.