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Ian
Joined: 24 May 2006
Posts: 6
Location: Canberra Australia
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 Posted: Thu Jan 24, 2008 9:49 pm Post subject: From the Sydney Morning Herald 12-1-08. Help Please! |
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Code
xx9 x5x 7x3
x3x 4x2 x9x
6xx xxx xx8
xxx 581 xxx
x7x xxx x4x
xxx 274 xx8
5xx xxx xx2
x1x 6x3 x5x
7x3 x2x 1xx
The Solver says its too hard. |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Thu Jan 24, 2008 10:17 pm Post subject: |
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Hi Ian,
The grid contains an error, with two 8s in column 9. For purposes of this reply, I've assumed r6c9 should be blank, and if that's the case, this is the grid with computer-generated pencil marks.
| Code: |
+------------------+--------------+------------------+
| 1248 9 1248 | 18 5 68 | 7 126 3 |
| 18 3 1578 | 4 16 2 | 56 9 156 |
| 6 245 12457 | 1379 139 79 | 245 12 8 |
+------------------+--------------+------------------+
| 2349 246 2469 | 5 8 1 | 2369 2367 679 |
| 12389 7 125689 | 39 369 69 | 235689 4 1569 |
| 1389 568 15689 | 2 7 4 | 35689 1368 1569 |
+------------------+--------------+------------------+
| 5 468 4689 | 1789 149 789 | 34689 3678 2 |
| 2489 1 2489 | 6 49 3 | 489 5 479 |
| 7 468 3 | 89 2 5 | 1 68 469 |
+------------------+--------------+------------------+
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Play this puzzle online at the Daily Sudoku site
This is the grid after some basic moves.
| Code: |
+----------------+--------------+-----------------+
| 124 9 124 | 18 5 68 | 7 126 3 |
| 8 3 7 | 4 16 2 | 56 9 156 |
| 6 25 125 | 379 39 79 | 24 12 8 |
+----------------+--------------+-----------------+
| 2349 246 2469 | 5 8 1 | 2369 7 69 |
| 12 7 1258 | 39 369 69 | 258 4 15 |
| 139 568 15689 | 2 7 4 | 35689 1368 1569 |
+----------------+--------------+-----------------+
| 5 468 4689 | 1789 149 789 | 34689 368 2 |
| 249 1 2489 | 6 49 3 | 489 5 7 |
| 7 468 3 | 89 2 5 | 1 68 469 |
+----------------+--------------+-----------------+
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Play this puzzle online at the Daily Sudoku site
The next move would be the Type 6 UR on 39 in boxes 2 and 5. Both r3c5 and r5c4 must be = 3.
Also, I just noticed the 125 naked triple (or hidden single 4) in row 3. |
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Ian
Joined: 24 May 2006
Posts: 6
Location: Canberra Australia
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| Posted: Fri Jan 25, 2008 3:09 am Post subject: |
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Dear Marty
Sorry, I made a mistake. You are correct in that r6c9 is blank. Thanks very much for the speedy reply. I didn't see the UR.
Regards
Ian |
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Asellus
Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA
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| Posted: Fri Jan 25, 2008 10:29 am Post subject: |
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Oh dear! There are errors compounded.
Marty,
You put the <9> in the wrong cell of box 1. I'm afraid your grid isn't valid.
Ian,
Here is the (presumably correct) grid after basics:
| Code: | +----------------+--------------+----------------+
| 124 24 9 | 18 5 68 | 7 126 3 |
| 8 3 7 | 4 16 2 | 56 9 156 |
| 6 25 125 | 379 39 79 | 4 12 8 |
+----------------+--------------+----------------+
| 2349 2469 246 | 5 8 1 | 236 7 69 |
| 12 7 1258 | 39 369 69 | 258 4 15 |
| 139 5689 1568 | 2 7 4 | 3568 1368 1569 |
+----------------+--------------+----------------+
| 5 4689 468 | 1789 149 789 | 3689 368 2 |
| 249 1 248 | 6 49 3 | 89 5 7 |
| 7 689 3 | 89 2 5 | 1 68 4 |
+----------------+--------------+----------------+ |
The Type 6 {39} UR is still there. Also, you might want to do some fishing. |
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Steve R
Joined: 24 Oct 2005
Posts: 289
Location: Birmingham, England
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| Posted: Fri Jan 25, 2008 3:40 pm Post subject: |
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Uniqueness solves it in one go, I think.
Marty has already excluded 3 from r3c4. 9 may also be eliminated using the UR based on (79) in r37c46.
Steve |
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Earl
Joined: 30 May 2007
Posts: 677
Location: Victoria, KS
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| Posted: Fri Jan 25, 2008 4:06 pm Post subject: Sydney Herald |
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Steve,
Could you show the details of how you used the UR (79).
Any UR above UR1 confuses me.
Thanks
Earl |
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Steve R
Joined: 24 Oct 2005
Posts: 289
Location: Birmingham, England
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| Posted: Fri Jan 25, 2008 4:48 pm Post subject: |
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Earl,
I hope this helps:
| Code: | +----------------+-----------------+----------------+
| 124 24 9 | 18 5 68 | 7 126 3 |
| 8 3 7 | 4 16 2 | 56 9 156 |
| 6 25 125 | 79 39 79 | 4 12 8 |
+----------------+-----------------+----------------+
| 2349 2469 246 | 5 8 1 | 236 7 69 |
| 12 7 1258 | 39 369 69 | 258 4 15 |
| 139 5689 1568 | 2 7 4 | 3568 1368 1569 |
+----------------+-----------------+----------------+
| 5 4689 468 | 79+18 149 79+8 | 3689 368 2 |
| 249 1 248 | 6 49 3 | 89 5 7 |
| 7 689 3 | 89 2 5 | 1 68 4 |
+----------------+-----------------+----------------+ |
In the r37c46 UR the bottom two cells between them must contain 8 or the one on the left contains 1. If 8, the (89) in r9c4 contains 9. if 1, then the (18) in r1c4 again causes r9c4 to contain 9.
So r9c4 is 9 and r3c4 is 7. The rest is easy.
Steve |
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Ian
Joined: 24 May 2006
Posts: 6
Location: Canberra Australia
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| Posted: Sat Jan 26, 2008 3:11 am Post subject: |
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| Thanks to everyone for all your help. |
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