- Code: Select all
`. . .|. . .|. . .`

6 . .|. . .|5 . .

8 . .|4 . 9|. . .

-----+-----+-----

. . .|. . .|. . .

. . .|. . .|. . .

. . .|7 . .|. . .

-----+-----+-----

. . .|. 1 .|7 . 6

9 . .|. . .|2 . .

3 2 .|. . .|. 8 .

I also tested these and wrote a little solving guide appendix:

NRC-Sudoku extra solving techniques.

The NRC-Sudoku has 4 additional AllDifferent constraints in 3x3 regions at rows 234 & 678 and colums 234 & 678.

I will call these the NRC-Boxes.

Intersection removals

When all candidates for digit d in a row or column are members of an NRC-Box, the remaining candidates for digit d can be eliminated from that NRC-Box.

When all candidates for digit d in an NRC-Box are members of a single row or column, the remaining candidates for digit d can be eliminated from that row or column.

When all candidates for digit d in a Box are members of an NRC-Box, the remaining candidates for digit d can be eliminated from that NRC-Box.

When all candidates for digit d in an NRC-Box are members of a single Box, the remaining candidates for digit d can be eliminated from that Box.

Disjoint subsets

All normal subset rules also apply to the NRC boxes.

NRC-Wing

When all candidates in 2 NRC-Boxes for digit d are located in exactly 2 rows or columns, the remaining candidates for digit d can be eliminated from those 2 rows or columns.

X-chains and coloring

Conjugate pairs can also be found in the NRC-Boxes.

Happy solving.

Ruud.