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July 18 DB

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Earl

Joined: 30 May 2007
Posts: 677
Location: Victoria, KS

Posted: Sat Jul 18, 2009 2:18 pm Post subject: July 18 DB

The July 18 DB employs the old reliable of a Dailysudoku VH.

Solution: 345 xy-wing makes R4C1 = 4 and solves it.

Earl

Code:

+-------+-------+-------+
| . . 8 | . . 4 | . . 2 |
| . . 9 | 3 . . | . 5 . |
| 6 . . | 5 . 2 | . . 7 |
+-------+-------+-------+
| . 2 . | 9 . 7 | 3 . . |
| . 3 . | . . . | . 7 . |
| . . 7 | 4 . 1 | . 2 . |
+-------+-------+-------+
| 1 . . | 2 . 3 | . . 6 |
| . 8 . | . . 6 | 5 . . |
| 7 . . | 8 . . | 2 . . |
+-------+-------+-------+

Play this puzzle online at the Daily Sudoku site

storm_norm

Joined: 18 Oct 2007
Posts: 1741

Posted: Sun Jul 19, 2009 5:37 am Post subject:

Code:

.------------------.------------------.------------------.
| 35 157 8 | 17 1679 4 | 169 1369 2 |
| 2 147 9 | 3 167 8 | 146 5 14 |
| 6 14 34 | 5 19 2 | 8 1349 7 |
:------------------+------------------+------------------:
| 45 2 1456 | 9 8 7 | 3 146 145 |
|U89 3 14 | 6 2 5 | 149 7 U1489 |
|U89 56 7 | 4 3 1 | 69 2 U589 |
:------------------+------------------+------------------:
| 1 9 45 | 2 45 3 | 7 8 6 |
| 34 8 2 | 17 147 6 | 5 149 134[9] |
| 7 456 3456 | 8 145 9 | 2 14 134 |
'------------------'------------------'------------------'

also notice the UR89 in r56c19.
if you aren't able to see the locked set {1,4,5} in column 9 formed by the UR, then there is a shortcut...

the 8's are locked in a perfect x-wing... and there is only one other 9 in columns 1 and 9. it resides in r8c9. this cell can only contain 9 since it has to be there to avoid the UR. this eliminates 134 from that cell and also solves it in one step.

tlanglet

Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills

Posted: Sun Jul 19, 2009 1:48 pm Post subject:

Nice observation Norm..... Ted

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