The New Sudoku Players' Forum

[apatt]

I am having problems with this one :

. . . | 3 7 . | 1 8 6
. . . | . . . | 4 . .
7 3 . | . . . | . 2 9
-------+-------+------
. . 6 | . 2 . | . 5 .
. . . | 9 . 8 | . . .
. . . | . 1 . | 3 . .
-------+-------+------
4 6 . | . . . | . 9 5
. . 7 | . . . | . . .
8 1 9 | . 6 7 | . . .


I got as far as:

. . . | 3 7 . | 1 8 6
6 . . | . . . | 4 . .
7 3 . | . . . | 5 2 9
-------+-------+------
1 . 6 | . 2 3 | 9 5 .
. . . | 9 . 8 | 6 1 .
. . . | . 1 . | 3 . .
-------+-------+------
4 6 . | . . . | 7 9 5
. . 7 | . . . | 8 6 1
8 1 9 | 5 6 7 | 2 . .

From then on I can't seem to find any pairs, triples, quads or unique candidates.

Hope you can help.

Thank you.

[Nick70]

This puzzle doesn't have a unique solutions. It has 28.

[apatt]

Wow! How do you work out the number of possible solutions? Any way, thanks very much, so it's not my fault after all for being stumped.

[scrose]

To determine if a puzzle has multiple solutions, you can use rubylips' app; input your puzzle and click the Evaluate button. If you want to know the exact number of solutions, you can use rubylips' command-line solver or simes' program.

Update: It looks like you are missing a clue at r6c2. If you place a 7 in that cell you will get a symmetrical puzzle with a unique solution.

Aside: It is interesting to note that if you place a 5 at r6c2 you almost get a unique solution; 2 to be exact.