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David Bryant
Joined: 29 Jul 2005 Posts: 559 Location: Denver, Colorado
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Posted: Thu Mar 09, 2006 3:58 pm Post subject: "Nightmare" for Thursday, 9 March, 2006 |
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This puzzle isn't nearly as hard as the "zen" sudoku I posted here yesterday, but it's still plenty tough. I found two different "5-star constellations" before I was able to solve it.
Code: | .6..2....
..84..7.1
..16....2
7..1.....
..9.7.6..
.....4..3
9....53..
3.5..24..
....4..8. |
Enjoy! dcb
PS In reworking this puzzle I noticed that the first "5-star constellation" I found was not really necessary -- there was a triplet {7, 8, 9} that would have served the same purpose, if I had only noticed it. |
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keith
Joined: 19 Sep 2005 Posts: 3355 Location: near Detroit, Michigan, USA
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Posted: Thu Mar 09, 2006 10:27 pm Post subject: Color me again! |
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David,
I found that early on there is a coloring on <7> which excludes that value from R9C3. This is a big help. Then, the puzzle can be solved via an X-wing on <3> (which also appears early), and the last step is an XY-wing on <9>. (After that, all moves are forced.)
Keith |
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someone_somewhere
Joined: 07 Aug 2005 Posts: 275 Location: Munich
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Posted: Sun Mar 12, 2006 2:51 pm Post subject: |
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Hi,
Just tried this one, in order to check that I am still alive ...
I foud for digit 3 a X-Wing on Column in: r2c2 r2c6 r5c2 r5c6
so I could eliminate it from: r3c2, r3c6, r4c2, r4c6, r9c6
and so 3 is in r9c4 as Unique Horizontal.
Now I excluded 6 from r4c3, because it would otherwise force a 6 in r9c1 and r9c6.
Followed by 9 not in r3c5 because of an XY-wing (that I leave to you to find) and by 9 not in r4c6 because of an other similar XY-wing.
Finally, I excluded 1 from r6c2, because it would give a contradiction on row with r9c1 and r9c7 for digit 1.
P.S. galaxies behind the "zen" one !!!
see u, |
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