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Puzzle 10/03/20 (A)

 
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daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Sat Mar 20, 2010 3:27 pm    Post subject: Puzzle 10/03/20 (A) Reply with quote

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

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

PostPosted: Sat Mar 20, 2010 6:50 pm    Post subject: Reply with quote

First time I've seen this! After a 48 UR, and cleaning up:
Code:
+----------------+----------------+----------------+
| 9    578  57   | 3    2    18   | 15   4    6    |
| 458  2    45   | 6    7    18   | 3    9    15   |
| 13   13   6    | 5    4    9    | 2    8    7    |
+----------------+----------------+----------------+
| 2    145  145  | 9    6    7    | 8    3    15   |
| 6    9    8    | 1    5    3    | 4    7    2    |
| 157  157  3    | 4    8    2    | 15   6    9    |
+----------------+----------------+----------------+
| 45   45   9    | 2    3    6    | 7    1    8    |
| 78   6    2    | 78   1    4    | 9    5    3    |
| 1378 1378 17   | 78   9    5    | 6    2    4    |
+----------------+----------------+----------------+

Look at R16C56. There is a DP 28, so R1C6 must be 1.

(Actually, the elimination of 8 in R1C6 was in a UR I didn't use.)

Danny, are there any solvers that include solved cells in their search for UR's?

Keith

EDIT: See thread in "Solving Techniques".
http://www.dailysudoku.com/sudoku/forums/viewtopic.php?&p=22627#22627
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Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA

PostPosted: Sun Mar 21, 2010 4:59 am    Post subject: Reply with quote

I didn't use that DP because I had read about it before I did the puzzle. A Type 1 UR (48), Type 4 (13) and a W-Wing (45) did the job.
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daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Tue Mar 23, 2010 10:38 pm    Post subject: Reply with quote

Hobiwan just released a new version of HoDoKu. (link is to announcement which contains additional links.)

In this version, you can input a partially solved grid and then add the original puzzle information. HoDoKu then knows where the givens reside in the partially solved grid ... and will find the Avoidable Rectangle Type 1/2 if present.

I tested it on this puzzle and it located Keith's elimination.

Regards, Danny
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