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Feb 25th H

 
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molerboy



Joined: 01 Mar 2009
Posts: 2

PostPosted: Sun Mar 01, 2009 10:26 pm    Post subject: Feb 25th H Reply with quote

Would anyone mind helping a newbie on a "Hard" puzzle. I've been doing easy/medium puzzles for months, and decided to try a hard one. I've gotten the puzzle as far as I can with the methods I've learned. Either I'm missing something in the methods I already know, or there's another method I need to learn to solve this puzzle. Can any help? If it's a method I need to learn, I'd be more interested in knowing what that is, then the actual solved puzzle.

Thanks

+-----------+------------+-----------+
| 8 9 6 | 5 1 3 | 7 2 4 |
| 2 1 7 | 9 8 4 | 6 3 5 |
| 4 3 5 | 26 7 26 | 1 8 9 |
+-----------+------------+-----------+
| 19 46 23 | 1236 5 9 | 8 49 7 |
| 19 456 23 | 7 36 8 | 23 459 16 |
| 7 56 8 | 1236 4 9 | 23 59 16 |
+-----------+------------+-----------+
| 5 8 14 | 46 2 7 | 9 16 3 |
| 6 2 49 | 34 39 1 | 5 7 8 |
| 3 7 19 | 8 69 5 | 4 16 2 |
+-----------+------------+-----------+
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Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA

PostPosted: Sun Mar 01, 2009 10:33 pm    Post subject: Re: Feb 25th H Reply with quote

molerboy wrote:
Would anyone mind helping a newbie on a "Hard" puzzle. I've been doing easy/medium puzzles for months, and decided to try a hard one. I've gotten the puzzle as far as I can with the methods I've learned. Either I'm missing something in the methods I already know, or there's another method I need to learn to solve this puzzle. Can any help? If it's a method I need to learn, I'd be more interested in knowing what that is, then the actual solved puzzle.

Thanks

Code:
+-----------+------------+-----------+
| 8  9   6  | 5    1  3  | 7  2   4  |
| 2  1   7  | 9    8  4  | 6  3   5  |
| 4  3   5  | 26   7  26 | 1  8   9  |
+-----------+------------+-----------+
| 19 46  23 | 1236 5  9  | 8  49  7  |
| 19 456 23 | 7    36 8  | 23 459 16 |
| 7  56  8  | 1236 4  9  | 23 59  16 |
+-----------+------------+-----------+
| 5  8   14 | 46   2  7  | 9  16  3  |
| 6  2   49 | 34   39 1  | 5  7   8  |
| 3  7   19 | 8    69 5  | 4  16  2  |
+-----------+------------+-----------+

Hi,
Welcome to the forum. There is a naked pair of 23 in row 5. See how far that takes you and feel free to come back for further questions.
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molerboy



Joined: 01 Mar 2009
Posts: 2

PostPosted: Mon Mar 02, 2009 1:30 am    Post subject: Naked pairs Reply with quote

I didn't know what a naked pair was, so I checked it out on some video demos. I see that naked pair in row 5 now, but I don't think the naked pair strategy helps me here (unless I still don't understand it well enough) because there's also a 23 in row 6 in F, and in row 4 in D. Can you explain any further?
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keith



Joined: 19 Sep 2005
Posts: 3344
Location: near Detroit, Michigan, USA

PostPosted: Mon Mar 02, 2009 2:47 am    Post subject: Reply with quote

Molerboy,

What you have posted is invalid. There two <9>'s in C6.

In any event, for what you have posted, R3C6 must be <2> in C6, and R6C8 must be <9> in R6.

Also, the <23> pair in R5 means that R5C5 is not <3>.

Keith
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Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA

PostPosted: Mon Mar 02, 2009 4:43 am    Post subject: Re: Naked pairs Reply with quote

molerboy wrote:
I didn't know what a naked pair was, so I checked it out on some video demos. I see that naked pair in row 5 now, but I don't think the naked pair strategy helps me here (unless I still don't understand it well enough) because there's also a 23 in row 6 in F, and in row 4 in D. Can you explain any further?


Molerboy,

Try this explanation and see if it helps. The same principle applies to a triple or a quad as well.

http://www.sudopedia.org/wiki/Naked_Pair
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