> -----Original Message-----
> From: Adam Shelly [mailto:adam.shelly / gmail.com] 
> Sent: Tuesday, August 23, 2005 1:54 PM
> To: ruby-talk ML
> Subject: Re: [QUIZ] Sodoku Solver (#43)
> 
> Ok, I've updated my version to resort to guessing when it can't deduce
> all the values.
> It guesses pretty slowly, my worst time was
> [...]
> 
> And it took a while to figure out that this one was unsolvable:
> +-------+-------+-------+
> | _ 2 _ | _ _ _ | _ _ _ |
> | _ _ _ | 6 _ _ | _ _ 3 |
> | _ 7 4 | _ 8 _ | _ _ _ |
> +-------+-------+-------+
> | _ _ _ | _ _ 3 | _ _ 2 |
> | _ 8 _ | _ 4 _ | _ 1 _ |
> | 6 _ _ | 5 _ _ | _ _ _ |
> +-------+-------+-------+
> | _ _ _ | _ 1 _ | 7 8 _ |
> | 5 _ _ | _ _ 9 | _ _ _ |
> | _ _ _ | _ _ _ | _ 4 _ |
> +-------+-------+-------+
> 
> UNSOLVABLE

Hmm, what about

                     user     system      total        real
solving nr 1     0.110000   0.000000   0.110000 (  0.110000)
+-------+-------+-------+
| 1 2 6 | 4 3 5 | 9 7 8 |
| 8 5 9 | 6 7 1 | 4 2 3 |
| 3 7 4 | 9 8 2 | 5 6 1 |
+-------+-------+-------+
| 4 1 7 | 8 9 3 | 6 5 2 |
| 2 8 5 | 9 4 6 | 3 1 7 |
| 6 3 1 | 5 2 7 | 8 9 4 |
+-------+-------+-------+
| 9 6 2 | 3 1 4 | 7 8 5 |
| 5 4 8 | 2 7 9 | 1 3 6 |
| 7 1 3 | 2 1 8 | 2 4 9 |
+-------+-------+-------+

? (I missed something, right?)

cheers

Simon