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Earl
Joined: 30 May 2007
Posts: 677
Location: Victoria, KS
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 Posted: Sat Jun 12, 2010 1:44 pm Post subject: June 12 DB |
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The June 12 DB is an apparent one stepper.
A Solution: skyscraper in 2
Earl
| Code: |
+-------+-------+-------+
| . . 2 | . 7 6 | 3 . . |
| . 9 . | 4 2 . | . . . |
| . . 4 | . . 5 | . . 2 |
+-------+-------+-------+
| 4 . 7 | . . . | . 9 . |
| . 5 . | . . . | . 7 . |
| . 8 . | . . . | 2 . 5 |
+-------+-------+-------+
| 5 . . | 6 . . | 7 . . |
| . . . | . 1 7 | . 3 . |
| . . 9 | 5 4 . | 6 . . |
+-------+-------+-------+
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Play this puzzle online at the Daily Sudoku site |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Sat Jun 12, 2010 8:42 pm Post subject: |
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Have you noticed lately that a skyscraper always seems to solve these?
After basics: | Code: | +----------------+----------------+----------------+
| 8 1 2 | 9 7 6 | 3 5 4 |
| 36 9 5 | 4 2 38 | 1 68 7 |
| 367 367 4 | 1 38 5 | 9 68 2 |
+----------------+----------------+----------------+
| 4 26a 7 | 23 5 1 | 8 9 36 |
| 1269 5 1-6 | 238 689 29 | 4 7 36 |
| 369 8 3-6 | 7 69 4 | 2 1 5 |
+----------------+----------------+----------------+
| 5 23b 138 | 6 389 29 | 7 4 18 |
| 26c 4 68d | 28 1 7 | 5 3 9 |
| 137 37 9 | 5 4 38 | 6 2 18 |
+----------------+----------------+----------------+ |
There is a nice M-wing that blows it out of the water.
If a is 2, b is not 2, c is 2, d is 6. ad are pincers on 6.
Keith |
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Auburnmom
Joined: 13 Mar 2008
Posts: 25
Location: Auburn, AL
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| Posted: Sat Jun 12, 2010 11:22 pm Post subject: |
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| Could you offer some explanation of skyscraper. I have tried to understand this method, but can't seem to put it to use. Thanks |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Sat Jun 12, 2010 11:55 pm Post subject: |
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A Skyscraper occurs when there are two pairs of strong links on a number in rows or columns and one half of each strong link share a row or column.
Looks at Keith's grid. There are strong links (only two possibilities) on 2 in rows 4 and 8. The shared part of each strong link is in column 4. Since it's impossible for both 2s in column 4 to be true, either the 2 in r4c2 or r8c1 must be true. Any 2 that sees both of those possibilities can be deleted.
There's an explanation here, but there are probably shorter explanations
elsewhere.
http://www.sudoku.frihost.net/forum/viewtopic.php?t=323&highlight=strong+links
Here's an "elsewhere":
http://www.sudopedia.org/wiki/Skyscraper |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Sun Jun 13, 2010 12:32 am Post subject: |
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| Auburnmom wrote: | | Could you offer some explanation of skyscraper. I have tried to understand this method, but can't seem to put it to use. Thanks |
Auburn,
Check this out:
http://www.sudoku.frihost.net/forum/viewtopic.php?t=323&highlight=strong+links
There are many (including me) who will say this is the most enlightening article on Sudoku they ever read.
Keith |
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Auburnmom
Joined: 13 Mar 2008
Posts: 25
Location: Auburn, AL
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| Posted: Sun Jun 13, 2010 2:44 pm Post subject: |
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| Thanks for the help. I was able to solve this puzzle, but don't know if I will be able to find it on my own another day. But wait, I did master the XYZ wing so maybe.... |
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