. . 1  . . .  4 . .
. . .  1 . 6  . 9 .
6 . .  . 8 .  . . 7

. 5 .  . . 9  . 3 .
. . 9  . . .  1 . .
. 4 .  7 . .  . 2 .

5 . .  . 9 .  . . 2
. 1 .  6 . 7  . . .
. . 2  . . .  6 . .
==
Solution
9 8 1  2 7 3  4 6 5
4 3 7  1 5 6  2 9 8
6 2 5  9 8 4  3 1 7

2 5 8  4 1 9  7 3 6
7 6 9  5 3 2  1 8 4
1 4 3  7 6 8  5 2 9

5 7 6  3 9 1  8 4 2
8 1 4  6 2 7  9 5 3
3 9 2  8 4 5  6 7 1
==
Create
Regexp::Sudoku:: -> new -> init -> set_diagonal_double
==
Name: Double Diagonal Sudoku (Fun With Sudoku #184)
URL: https://www.funwithpuzzles.com/2016/03/double-diagonal-sudoku.html