17 March, 2006

[David Bryant]

Happy St. Patrick's Day!

I really liked this puzzle, Ruud. With 42 cells filled in I found a nice "6-star constellation" that allowed me to set the value in r7c9. That wasn't quite enough to crack it, though ... after completing 16 more cells I had to find an XY-Wing to wrap the whole thing up. dcb

[keith]

David,

Seeing your message, I had to try it. I got to this point with basic methods:

Code: Select all

+----------------+----------------+----------------+
| 6    39   2    | 5    4    19   | 7    38   18   | 
| 7    39   8    | 2    6    19   | 13   4    5    | 
| 1    4    5    | 78   78   3    | 6    9    2    | 
+----------------+----------------+----------------+
| 5    78   3    | 4    789  2    | 89   1    6    | 
| 9    178  167  | 678  3578 5678 | 238  2378 4    | 
| 4    2    67   | 1    3789 678  | 5    378  789  | 
+----------------+----------------+----------------+
| 8    6    14   | 3    2    57   | 149  57   19   | 
| 3    5    47   | 9    1    678  | 248  2678 78   | 
| 2    17   9    | 678  578  4    | 18   5678 3    | 
+----------------+----------------+----------------+

Now, there are three XY-wings! If you spot the wing on <7>, it will reveal a swordfish!

Not all of these are needed to solve the puzzle.

Keith

Keith

[David Bryant]

Yup, that's the spot I was at when I found the "constellation." I didn't notice the XY-Wings at this stage ... I concentrated on r2c7, and saw that whichever value is placed there, r7c9 is still the same. dcb