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Earl
Joined: 30 May 2007 Posts: 677 Location: Victoria, KS
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Posted: Wed Jan 20, 2010 4:01 am Post subject: Jan 20 VH |
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The old reliable does it again, but there are interesting alternate paths.
A Solution: 569 xy-wing does it in one stroke; but there is an interesting 78 UR which creates a virtual cell (46) leaving R2C9 = 8, yet that requires further steps.
Early Earl |
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Marty R.
Joined: 12 Feb 2006 Posts: 5770 Location: Rochester, NY, USA
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Posted: Wed Jan 20, 2010 4:47 am Post subject: |
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There were also W-Wings available, one on 69 and two on 56, using two different pairs of 56 cells. |
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cgordon
Joined: 04 May 2007 Posts: 769 Location: ontario, canada
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Posted: Wed Jan 20, 2010 1:40 pm Post subject: |
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I actually ended up using 4 steps (sans wings).
Type 4 UR (78)
sky (or ER) on 6
sky on 5
Bug+1
Good one! |
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arkietech
Joined: 31 Jul 2008 Posts: 1834 Location: Northwest Arkansas USA
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Posted: Wed Jan 20, 2010 3:45 pm Post subject: |
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The w-wing 56 removing the 5 in r8c1 makes it a one stepper.
Two good ones in a row! |
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Ema Nymton
Joined: 17 Apr 2009 Posts: 89
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Posted: Thu Jan 21, 2010 11:12 am Post subject: |
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.
Please,
arkietech wrote: | The w-wing 56 removing the 5 in r8c1 makes it a one stepper.
Two good ones in a row! :D |
Given:
Code: |
+------------+------------+------------+
| 56 1 8 | 456 46 9 | 7 3 2 |
| 3 256 4 | 56 7 12 | 158 9 58 |
| 7 9 25 | 3 8 12 | 145 6 45 |
+------------+------------+------------+
| 8 3 9 | 7 2 4 | 6 5 1 |
| 1 25 25 | 9 3 6 | 48 78 478 |
| 4 7 6 | 8 1 5 | 3 2 9 |
+------------+------------+------------+
| 69 4 1 | 2 5 3 | 89 78 678 |
| 569 8 3 | 46 469 7 | 2 1 56 |
| 2 56 7 | 1 69 8 | 59 4 3 |
+------------+------------+------------+
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Walk one through this. It may be obvious to some, but for others, the reasoning is obscure.
How does the sets of '56' remove the '5' in r8c1?
Thank you.
Ema Nymton
~@:o?
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http://www.brainbashers.com/sudokuhelp.asp |
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Marty R.
Joined: 12 Feb 2006 Posts: 5770 Location: Rochester, NY, USA
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Posted: Thu Jan 21, 2010 4:45 pm Post subject: |
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Ema Nymton wrote: | .
Please,
arkietech wrote: | The w-wing 56 removing the 5 in r8c1 makes it a one stepper.
Two good ones in a row! |
Given:
Code: |
+------------+------------+------------+
| 56 1 8 | 456 46 9 | 7 3 2 |
| 3 256 4 | 56 7 12 | 158 9 58 |
| 7 9 25 | 3 8 12 | 145 6 45 |
+------------+------------+------------+
| 8 3 9 | 7 2 4 | 6 5 1 |
| 1 25 25 | 9 3 6 | 48 78 478 |
| 4 7 6 | 8 1 5 | 3 2 9 |
+------------+------------+------------+
| 69 4 1 | 2 5 3 | 89 78 678 |
| 569 8 3 | 46 469 7 | 2 1 56 |
| 2 56 7 | 1 69 8 | 59 4 3 |
+------------+------------+------------+
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Walk one through this. It may be obvious to some, but for others, the reasoning is obscure.
How does the sets of '56' remove the '5' in r8c1?
Thank you.
Ema Nymton
~@?
.
http://www.brainbashers.com/sudokuhelp.asp |
Ema,
Note the 6s in row 7. If R7c1=6 then r9c2 must be = 5. If r7c9=6, then r8c9 must be = 5. Since one or the other must be = 5, then no cell seeing both 5s can contain a 5.
Note "Chapter 4" here for a general view of the W-Wing.
http://www.dailysudoku.co.uk/sudoku/forums/viewtopic.php?t=2143 |
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