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Earl
Joined: 30 May 2007
Posts: 677
Location: Victoria, KS
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 Posted: Tue Apr 21, 2009 1:51 am Post subject: April 21 VH |
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Probably the most common solution to a Daily Sudoku VH.
SOLUTION: xy-wing (258): two alignments, take your pick.
Early Earl |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Tue Apr 21, 2009 3:44 am Post subject: |
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| This one practically solved itself. By the time I finished populating the grid with pencil marks, it was already in a BUG+1 pattern, as well as having that XY-Wing available. |
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cgordon
Joined: 04 May 2007
Posts: 769
Location: ontario, canada
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| Posted: Tue Apr 21, 2009 11:18 am Post subject: |
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| I think the ones that end up with a BUG+1 qualify as the easiest of the VHs. Just like this one. There's one triple left, 589, which "sees" 58 and 59 in C1. Just look for the number that appears three times, in this case <5> - and shove it in the place of the triple. |
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sdq_pete
Joined: 30 Apr 2007
Posts: 119
Location: Rotterdam, NL
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| Posted: Tue Apr 21, 2009 3:45 pm Post subject: |
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After basics, this one was so nearly complete, I just chose a bivalue cell and assumed a value to see whether it lead to a contradiction (which it did) and accordingly filled in the other value... O.K. trial and error, but feasible in this case.
Peter |
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crunched
Joined: 05 Feb 2008
Posts: 168
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| Posted: Wed Apr 22, 2009 1:49 am Post subject: Re: April 21 VH |
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I solved this with 2 x-wings: 1s & 6s.
I went back to do it again, and used, same as before an x-wing on 1s (first and third columns as I recall); but I could not finish it with another x-wing this time! Did I err the first time around?
Below is where I landed, and could not budge with an x-wing.
Had to look for some other solution.
| Code: |
+-----------+--------+----------+
| 58 7 1 | 3 9 2 | 68 56 4 |
| 589 3 29 | 58 4 6 | 7 1 25 |
| 6 25 4 | 58 1 7 | 28 9 3 |
+-----------+--------+----------+
| 2 9 8 | 4 5 1 | 3 7 6 |
| 1 6 7 | 2 3 8 | 5 4 9 |
| 3 4 5 | 7 6 9 | 1 2 8 |
+-----------+--------+----------+
| 4 8 6 | 1 2 5 | 9 3 7 |
| 7 1 3 | 9 8 4 | 26 56 25 |
| 59 25 29 | 6 7 3 | 4 8 1 |
+-----------+--------+----------+
Earl, below, points out the solution from there.
[quote="Earl"]Probably the most common solution to a Daily Sudoku VH.
xy-wing (258): two alignments, take your pick.
Early Earl[/quote]
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Play ABOVE puzzle online at the Daily Sudoku site |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Wed Apr 22, 2009 3:52 am Post subject: |
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| Code: | +-----------+--------+----------+
| 58 7 1 | 3 9 2 | 68 56 4 |
| 589 3 29 | 58 4 6 | 7 1 25 |
| 6 25 4 | 58 1 7 | 28 9 3 |
+-----------+--------+----------+
| 2 9 8 | 4 5 1 | 3 7 6 |
| 1 6 7 | 2 3 8 | 5 4 9 |
| 3 4 5 | 7 6 9 | 1 2 8 |
+-----------+--------+----------+
| 4 8 6 | 1 2 5 | 9 3 7 |
| 7 1 3 | 9 8 4 | 26 56 25 |
| 59 25 29 | 6 7 3 | 4 8 1 |
+-----------+--------+----------+ |
I just noticed in this grid a move that hasn't been noted, a W-Wing on the 58 cells at r1c1 and r3c4, linked by the 8s in column 7 and which takes out the 5 from r3c2. |
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