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Puzzle 10/03/19 (B)

 
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daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Fri Mar 19, 2010 11:49 pm    Post subject: Puzzle 10/03/19 (B) Reply with quote

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 . |
 +-----------------------+

Play this puzzle online at the Daily Sudoku site
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tlanglet



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

PostPosted: Sat Mar 20, 2010 2:18 am    Post subject: Reply with quote

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

PostPosted: Sat Mar 20, 2010 8:28 am    Post subject: Reply with quote

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

PostPosted: Sun Mar 21, 2010 12:33 am    Post subject: Reply with quote

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

PostPosted: Sun Mar 21, 2010 1:32 pm    Post subject: Reply with quote

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


Dan, very nice find Exclamation

Ted
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