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dshannaaz
Joined: 30 Jul 2006
Posts: 2
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 Posted: Thu Oct 12, 2006 1:43 am Post subject: October 8 - Very Hard |
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| I usually struggle with the "hard" and "very hard" daily sudokus. I have also read that they are/will be getting even harder. Thus, I was surprised to speed through the October 8 "very hard" entry with nothing much more difficult than a naked pair. I am fairly certain I am not getting that much better and thus (alas) I wonder if it was mislabeled. |
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TKiel
Joined: 22 Feb 2006
Posts: 292
Location: Kalamazoo, MI
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| Posted: Thu Oct 12, 2006 10:24 pm Post subject: |
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Up to this point nothing is needed but singles and locked candidates (b/b interaction):
| Code: |
*-----------------------------------------------------------*
| 4 278 2578 | 35 6 25 | 59 379 1 |
| 9 12 125 | 4 235 7 | 6 8 35 |
| 57 3 6 | 8 1 9 | 4 27 25 |
|-------------------+-------------------+-------------------|
| 6 17 3 | 157 57 8 | 2 4 9 |
| 8 5 9 | 2 4 6 | 3 1 7 |
| 2 4 17 | 17 9 3 | 8 5 6 |
|-------------------+-------------------+-------------------|
| 35 28 4 | 9 235 1 | 7 6 2358 |
| 357 9 2578 | 6 2357 4 | 1 23 2358 |
| 1 6 257 | 357 8 25 | 59 239 4 |
*-----------------------------------------------------------*
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after which Simple Sudoku says that an X-wing is the simplest next step, and it solves the puzzle. Actually there are three X-wings at this point, two of which solve the puzzle. This fits with the site definition of a 'Very Hard' puzzle. Where did you find the naked pair? |
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dshannaaz
Joined: 30 Jul 2006
Posts: 2
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| Posted: Sat Oct 14, 2006 12:17 am Post subject: No X-wings |
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I am not sure if I can recreate the logic. I do know that I did NOT use X-wings. In "very hard" sudokus there is usually a "sticking point" somewhere around move #12. I just didn't find one in this puzzle.
My first 20 moves were as follows:
R8C7; R2C1; R6C5; R4C7; R5C5;
R9C2; R4C1; R6C7; R5C9; R5C1;
R6C8; R6C9; R3C7; R2C7; R1C8;
R3C8; R9C7; R1C7; R3C9; R2C9. |
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TKiel
Joined: 22 Feb 2006
Posts: 292
Location: Kalamazoo, MI
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| Posted: Thu Oct 19, 2006 1:24 am Post subject: |
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| These all seem to be naked or hidden singles, up to r3c7 which seemed to be the result of the (2,5,7) naked triple in row 3. That turned r2c7 into a single, but I couldn't figure out how or what you placed in r1c8 at this time. |
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