A standard 9x9 Sudoku grid is entirely empty except for two numbers in the bottom row. The bottom row looks like: 1, blank, 2, blank, blank, blank, blank, blank, blank.

The standard Sudoku rules apply: Each row and column must contain all the digits 1 to 9 and the smaller 3x3 blocks must also contain all the digits 1 to 9.

Two additional rules apply: Each of the positive diagonals must contain no repeating digits, and the adjacent digits along each positive diagonal must have a difference of 4 or more.

Note: the positive (sloped) diagonals are diagonals that run from southwest to northeast. To obey the difference rule, for example, the major positive diagonal can begin: 1, 5, 9, 3, ... but not 1, 6, 9, 3, ... because the difference between 9 and 6 is less than 4.

Find the unique solution for the full grid.

I found viewing the manual solution quite enjoyable. It is done in real time by an expert and it takes only 20 minutes. (You even get to hear the super mild oath: "bobbins!") 

Edited on May 14, 2022, 3:59 pm

Posted by Steven Lord on 2022-05-14 12:25:15