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2 puzzles with the same solution

 
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International_DBA

Joined: 25 Oct 2011
Posts: 4
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Location: UK

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PostPosted: Sun Jan 29, 2012 9:11 pm    Post subject: 2 puzzles with the same solution Reply with quote

Here is an easy puzzle, which you can solve with naked singles only.
Code:

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

In a moment, I will post a different puzzle with the same solution.
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International_DBA

Joined: 25 Oct 2011
Posts: 4
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Location: UK

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PostPosted: Sun Jan 29, 2012 9:21 pm    Post subject: 2nd puzzle Reply with quote

Here is the 2nd puzzle, which has the same solution as the 1st. In addition to naked singles, you also need to slice and dice at the box level to solve this one:
Code:

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

Joined: 13 Mar 2006
Posts: 341
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Location: Europe

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PostPosted: Sun Jan 29, 2012 11:55 pm    Post subject: Re: 2 puzzles with the same solution Reply with quote

International_DBA wrote:
Here is an easy puzzle, which you can solve with naked singles only.
Code:

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



Note, however, that the puzzle is not minimal:
Code:

  4 1  is redundant
  4 3  is redundant
  4 5  is redundant
  6 1  is redundant
  6 3  is redundant
 

Removing, for instance, the last three of these yields a minimal puzzle that is a lot more difficult.

Regards,

Mike Metcalf
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International_DBA

Joined: 25 Oct 2011
Posts: 4
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Location: UK

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PostPosted: Mon Jan 30, 2012 1:40 pm    Post subject: How I Produced the Puzzles Reply with quote

Dear Mike,

Thank you for taking the time to comment on my puzzles. I created them with a C program which I am writing. At first it just produced puzzles which could be solved by looking for naked singles. Now I have changed it to produce puzzles which also need slicing and dicing. What type of solving method should I add next?

Kind Regards,

Andrew
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m_b_metcalf

Joined: 13 Mar 2006
Posts: 341
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Location: Europe

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PostPosted: Tue Jan 31, 2012 12:46 am    Post subject: Re: How I Produced the Puzzles Reply with quote

International_DBA wrote:
What type of solving method should I add next?

Andrew, You need to look through the various lists of increasingly sophisticted techniques that you will find in these forums (pairs, triplets, pointing, X-wing, ...). But, in the end, you will need to have a backtracking solver that can handle any puzzle, fast. If you're wanting to code yourself, that's where to start. There are, of course, many solvers freely available, Brian Turner's being the whizz-bang one.

HTH

Mike Metcalf
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Pat

Joined: 06 Sep 2006
Posts: 243
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PostPosted: Sun Feb 05, 2012 12:51 pm    Post subject: Reply with quote

m_b_metcalf wrote:
International_DBA wrote:
Here is an easy puzzle,
which you can solve with naked singles only.
Code:

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



Removing r4c5 + r6c13
yields a minimal puzzle that is a lot more difficult.

thanks, m_b_metcalf !!
a nice puzzle indeed
        Code:

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

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
International_DBA wrote:
Here is the 2nd puzzle

In addition to naked singles,
you also need to slice and dice at the box level to solve this one:
Code:

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


so i don't know what is meant by "slice and dice"

but
this puzzle is solved by "singles",
not interesting


try adding box-line interactions
  • box\row (and box\column)
  • row\box (and column\box)
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PlanetSudoku.com

Joined: 21 Feb 2012
Posts: 6
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PostPosted: Tue Feb 21, 2012 6:01 pm    Post subject: Re: 2 puzzles with the same solution Reply with quote

m_b_metcalf wrote:
International_DBA wrote:
Here is an easy puzzle, which you can solve with naked singles only.
Code:

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



Note, however, that the puzzle is not minimal:
Code:

  4 1  is redundant
  4 3  is redundant
  4 5  is redundant
  6 1  is redundant
  6 3  is redundant
 

Removing, for instance, the last three of these yields a minimal puzzle that is a lot more difficult.

Regards,

Mike Metcalf


Mike,
Not to take this off of topic, but did you use any special methods for removing the redundant pens? I would guess you pulled a pen and tried to solve, if successful pull another, if not pull a different one and repeat?
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m_b_metcalf

Joined: 13 Mar 2006
Posts: 341
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Location: Europe

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PostPosted: Thu Mar 01, 2012 5:07 am    Post subject: Re: 2 puzzles with the same solution Reply with quote

PlanetSudoku.com wrote:

Mike,
Not to take this off of topic, but did you use any special methods for removing the redundant pens? I would guess you pulled a pen and tried to solve, if successful pull another, if not pull a different one and repeat?

Not quite, I selected one of the five at random, deleted it, checked for redundant clues again, and repeated until minimal. Other selections are possible.

Regards,

Mike Metcalf
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