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roaa
Joined: 18 Apr 2009
Posts: 112
Location: Sweden
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 Posted: Thu Sep 19, 2013 8:09 am Post subject: Sept 19 VH |
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| One step solution: xy-wing (245), pivot r7c1, forces r4c7=6, which makes it. |
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hughwill
Joined: 05 Apr 2010
Posts: 424
Location: Birmingham UK
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| Posted: Thu Sep 19, 2013 8:54 am Post subject: Sept 19 VH |
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After basics:
| Code: |
+------------+---------+------------+
| 8 1 4 | 6 7 25 | 3 9 25 |
| 2 5 6 | 9 3 1 | 4 8 7 |
| 7 9 3 | 8 4 25 | 1 256 256 |
+------------+---------+------------+
| 9 23 125 | 4 6 7 | 8 25 13 |
| 6 8 12 | 12 5 3 | 7 4 9 |
| 45 234 7 | 12 8 9 | 26 256 13 |
+------------+---------+------------+
| 45 247 8 | 57 1 6 | 9 3 24 |
| 3 267 25 | 57 9 4 | 26 1 8 |
| 1 46 9 | 3 2 8 | 5 7 46 |
+------------+---------+------------+
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Play this puzzle online at the Daily Sudoku site
Roaa said:
| Quote: | | One step solution: xy-wing (245), pivot r7c1, forces r4c7=6, which makes it. |
Yes, I got that too, but only after going up the 123 XY blind alley and
before seeing the (boring?) one-step Type 1 UR on 25 in boxes 2 and 3. |
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roaa
Joined: 18 Apr 2009
Posts: 112
Location: Sweden
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| Posted: Thu Sep 19, 2013 1:27 pm Post subject: |
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| I also saw both these before I landed in the best(?) xy 245 solution. |
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Dart45
Joined: 16 Apr 2008
Posts: 17
Location: Canada
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| Posted: Thu Sep 19, 2013 6:10 pm Post subject: |
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| Huh? What? r4c7 is not 6! So what's up here? |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Thu Sep 19, 2013 8:04 pm Post subject: |
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| Dart45 wrote: | | Huh? What? r4c7 is not 6! So what's up here? |
Maybe a typo. R8c7 is 6 after the 2 is eliminated. |
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RobertRattley
Joined: 24 Jun 2007
Posts: 118
Location: Australia
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| Posted: Mon Sep 23, 2013 2:18 pm Post subject: |
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I like 'very hard' puzzles that need a 'hard' step or two on the way. Here I needed a pair 46 in row 9.
Like roaa I also saw the two independent xy wings. I was curious as to whether they were both needed. I confirmed that the 123 xy wing was not enough (hughwill's "blind alley") and not even necessary: the 245 xy wing was necessary and sufficient. |
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