单对角线 Single Diagonal

单对角线是对角线的一种变型。在单对角线中，只有一条给定的对角线需要填入1~N不重复的数字。

Single Diagonal is a variant of Diagonal. In Single Diagonal, just one given diagonal needs 1~N numbers no repeated.

它的核心思路与对角线一致，但我们无法使用对角线的潜规则。

Methods are like Diagonal, but we can't use the Hidden Rules anymore.