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daj95376
Joined: 23 Aug 2008 Posts: 3854
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Posted: Fri Mar 19, 2010 11:49 pm Post subject: Puzzle 10/03/19 (B) |
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Code: | +-----------------------+
| 2 9 . | . . 8 | . . . |
| 1 . 3 | . 9 7 | . 2 6 |
| . 7 . | . . . | 5 . . |
|-------+-------+-------|
| . . . | 2 . . | 7 . . |
| . 6 . | . . . | . . . |
| 7 1 . | . . 6 | . 5 . |
|-------+-------+-------|
| . . 7 | 8 . . | 2 . . |
| . 3 . | . . 2 | . 9 5 |
| . 2 . | . . . | . 1 . |
+-----------------------+
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Play this puzzle online at the Daily Sudoku site |
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tlanglet
Joined: 17 Oct 2007 Posts: 2468 Location: Northern California Foothills
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Posted: Sat Mar 20, 2010 2:18 am Post subject: |
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An interesting one stepper.
Type 2 UR 46 in r18c45. As a type 2 UR, a 7 must go into r8c45, but this does not provide any deletions since row8 and box8 do not contain any other digit 7s.
However, looking at the implications outside the UR, we find that no other digits 4 or 6 occur in row1 but in row8 a 6 must occur in col17 or a 4 must occur in col1. Using this strong inference we get: UR 46 [(6)r8c17 = (4)r8c1)]r18c45 - (4=6)r9c3 - r9c7 = r8c7; r8c45<>6
Ted |
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arkietech
Joined: 31 Jul 2008 Posts: 1834 Location: Northwest Arkansas USA
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Posted: Sat Mar 20, 2010 8:28 am Post subject: |
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an ALS solves it in one step also: Code: | *-----------------------------------------------------------------------------*
| 2 9 5 | 46 46 8 | 13 7 13 |
| 1 8 3 | 5 9 7 | 4 2 6 |
| 46 7 46 | 13 2 13 | 5 8 9 |
|-------------------------+-------------------------+-------------------------|
| 35 4 89 | 2 1358 1359 | 7 6 138 |
| 35 6 289 | 13479 134578 13459 | 139 34 12348 |
| 7 1 289 | 349 348 6 | 39 5 2348 |
|-------------------------+-------------------------+-------------------------|
| 69 5 7 | 8 16 19 | 2 34 34 |
| 68-4 3 1 |a467 a467 2 |a68 9 5 |
| 4689 2 b46 | 369-4 356-4 359-4 |b68 1 7 |
*-----------------------------------------------------------------------------*
ALS
A=4678
B=468
X=8 c7
Z=4 |
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Marty R.
Joined: 12 Feb 2006 Posts: 5770 Location: Rochester, NY, USA
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Posted: Sun Mar 21, 2010 12:33 am Post subject: |
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I'll go with a four-stepper.
Type 1 UR (46)
Type 4 UR (68) utilizing a cell from which 6 had been removed by prior step
XY-Wing (486) with pincer transport
X-Wing (4) |
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tlanglet
Joined: 17 Oct 2007 Posts: 2468 Location: Northern California Foothills
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Posted: Sun Mar 21, 2010 1:32 pm Post subject: |
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arkietech wrote: | an ALS solves it in one step also: Code: | *-----------------------------------------------------------------------------*
| 2 9 5 | 46 46 8 | 13 7 13 |
| 1 8 3 | 5 9 7 | 4 2 6 |
| 46 7 46 | 13 2 13 | 5 8 9 |
|-------------------------+-------------------------+-------------------------|
| 35 4 89 | 2 1358 1359 | 7 6 138 |
| 35 6 289 | 13479 134578 13459 | 139 34 12348 |
| 7 1 289 | 349 348 6 | 39 5 2348 |
|-------------------------+-------------------------+-------------------------|
| 69 5 7 | 8 16 19 | 2 34 34 |
| 68-4 3 1 |a467 a467 2 |a68 9 5 |
| 4689 2 b46 | 369-4 356-4 359-4 |b68 1 7 |
*-----------------------------------------------------------------------------*
ALS
A=4678
B=468
X=8 c7
Z=4 |
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Dan, very nice find
Ted |
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