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Is this puzzle valid?

 
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Marty R.



Joined: 12 Feb 2006
Posts: 5179
Location: Rochester, NY, USA

PostPosted: Mon Jul 01, 2013 2:59 pm    Post subject: Is this puzzle valid? Reply with quote

If someone has Sudoku software, would you be kind enough to plug this in and let me know if it's valid? Thanks.

(Is there an online tool that can do this?)

Code:

+-------+-------+-------+
| 2 3 . | 8 . . | . 9 . |
| 1 . . | . . 5 | . . . |
| . . . | 1 . . | 4 . . |
+-------+-------+-------+
| . 2 7 | . . . | . . . |
| 5 1 . | . . . | . 8 2 |
| . . . | . . . | 6 5 . |
+-------+-------+-------+
| . . 6 | . . 2 | . . . |
| . . . | 3 . . | . . 5 |
| . 9 . | . . 7 | . 4 3 |
+-------+-------+-------+

Play this puzzle online at the Daily Sudoku site
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keith



Joined: 19 Sep 2005
Posts: 3184
Location: near Detroit, Michigan, USA

PostPosted: Mon Jul 01, 2013 3:15 pm    Post subject: Reply with quote

Yes, it is a valid puzzle.
Code:
+-------+-------+-------+
| 2 3 4 | 8 7 6 | 5 9 1 |
| 1 7 8 | 9 4 5 | 3 2 6 |
| 9 6 5 | 1 2 3 | 4 7 8 |
+-------+-------+-------+
| 6 2 7 | 5 9 8 | 1 3 4 |
| 5 1 3 | 7 6 4 | 9 8 2 |
| 4 8 9 | 2 3 1 | 6 5 7 |
+-------+-------+-------+
| 3 5 6 | 4 8 2 | 7 1 9 |
| 7 4 2 | 3 1 9 | 8 6 5 |
| 8 9 1 | 6 5 7 | 2 4 3 |
+-------+-------+-------+

Keith
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keith



Joined: 19 Sep 2005
Posts: 3184
Location: near Detroit, Michigan, USA

PostPosted: Mon Jul 01, 2013 3:36 pm    Post subject: Re: Is this puzzle valid? Reply with quote

Marty R. wrote:
If someone has Sudoku software, would you be kind enough to plug this in and let me know if it's valid? Thanks.

(Is there an online tool that can do this?)


Try Helmut's Sudoku Helper:

http://www.saueregger.at/sudoku/HSH/HSH.htm

Keith
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Marty R.



Joined: 12 Feb 2006
Posts: 5179
Location: Rochester, NY, USA

PostPosted: Mon Jul 01, 2013 4:44 pm    Post subject: Reply with quote

Thanks Keith. Every once in a while this happens. Four times I've done this puzzle and ended with an invalidity. I'm pretty sure it's valid but can't figure out what I'm doing wrong but feel better about trying it again when I know for sure it's valid.
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Pat



Joined: 23 Feb 2010
Posts: 165

PostPosted: Tue Jul 02, 2013 7:56 am    Post subject: Reply with quote

keith wrote:
Try Helmut's Sudoku Helper
nice tool,
but seems to accept all puzzles
regardless of number of answers


try Paul Stephens
    click import-export

    in the new window, paste the puzzle
    ( empty cell must be a dot )

    click import,
    then OK

      • 0 answers:
        pop-up window with clear warning

      • 2-or-more answers:
        warning is there but less clear
        ( red text on orange background ):
        "WARNING - This puzzle has more than one solution"
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nataraj



Joined: 03 Aug 2007
Posts: 1029
Location: Vienna, Austria

PostPosted: Tue Jul 02, 2013 4:02 pm    Post subject: Reply with quote

Indeed, the Sudoku Helper will try to solve the puzzle and does not check for validity. Therefore it might end with the "sorry, cannot solve it" message. or - worse - with an error.

I do have a tool that checks for number of solutions - which, BTW is part of the Sudoku creation process - but so far I've been reluctant to put parts of the Sudoku creation process out in the public domain ...

Let me think about it for a while, maybe I'll just go and put it on the server and make an addition to the Sudoku Formatter.

Helmut

THe puzzle in question though, is a valid puzzle and HSH gives those steps to solve it:


Found 1 solution(s) in 20 milliseconds.

234876591178945326965123478627598134513764982489231657356482719742319865891657243

Top rating=8

Statistics of steps taken: 7/94/6/5/0/0/2/1/3/0. time:1238 ms.

rating 2; Subset naked pair 47 box 7
rating 2; Subset naked pair 12 row 9
rating 2; Subset naked pair 47 row 8
rating 2; Subset naked pair 56 box 8
rating 3; Subset quad 1289 row 8
rating 3; Subset quad 3489 box 4
rating 3; Subset quad 2379 row 3
rating 3; Subset quad 3679 row 5
rating 3; Subset quint 13589 row 4
rating 7; m-wing (7) via "9" - 5 advanced moves available.
rating 2; Subset naked pair 68 box 3
rating 2; Subset naked pair 68 col 9
rating 8; Unique Rectangle ('UR') 12 - 3 advanced moves available.
rating 8; Unique Rectangle ('UR') 49 - 2 advanced moves available.
rating 6; kite (9) - 3 advanced moves available.
rating 6; coloring (9) - 2 advanced moves available.
rating 8; Unique Rectangle ('UR') 68 - 2 advanced moves available.
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Marty R.



Joined: 12 Feb 2006
Posts: 5179
Location: Rochester, NY, USA

PostPosted: Tue Jul 02, 2013 9:36 pm    Post subject: Reply with quote

For what it's worth, I solved it (on the 5th try) with an M-Wing on 79 and Type 1 UR on 68.
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