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A good "Very Hard"

 
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keith



Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
PostPosted: Sun Sep 28, 2008 11:10 pm    Post subject: A good "Very Hard" Reply with quote
This one is solvable by this site's "Very Hard" methods.

I recommend that you ignore the UR. The journey is much more interesting without it.

Code:
Puzzle: BB105662sh
+-------+-------+-------+
| . . . | 1 . 7 | . . . |
| . . 3 | . 4 . | 6 . . |
| . 7 . | . 6 . | . 5 . |
+-------+-------+-------+
| 6 . . | 7 . 8 | . . 9 |
| . 2 8 | . . . | 1 7 . |
| 5 . . | 3 . 1 | . . 8 |
+-------+-------+-------+
| . 6 . | . 7 . | . 9 . |
| . . 2 | . 1 . | 7 . . |
| . . . | 8 . 6 | . . . |
+-------+-------+-------+

Keith
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arkietech



Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA
PostPosted: Sun Sep 28, 2008 11:34 pm    Post subject: Reply with quote
Good puzzle Very Happy

I found two x-wings and three xy-wings to solve it. But I'm looking for someone to come up a cleaner route.
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tlanglet



Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
PostPosted: Mon Sep 29, 2008 2:08 am    Post subject: Reply with quote
arkietech wrote:
Good puzzle Very Happy

I found two x-wings and three xy-wings to solve it. But I'm looking for someone to come up a cleaner route.


Dan, I also found two x-wings and three xy-wings. I strongly expect that one of the x-wings is not necessary and I may do the puzzle again to see if I can find a shorter path.

And yes, I also found the puzzle very enjoyable.

Ted
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keith



Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
PostPosted: Mon Sep 29, 2008 6:16 am    Post subject: Reply with quote
Ignoring the UR, I think the following are necessary: X-wing, XY-wing, X-wing, XY-wing. There is an unnecessary XYZ-wing lurking in there.

Then, for the final step, an XY-wing on either <234> or <235> will do it.

Keith
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