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True Sudoku?

 
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wossname

Joined: 03 Aug 2007
Posts: 1
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PostPosted: Fri Aug 03, 2007 9:33 pm    Post subject: True Sudoku? Reply with quote

I have spent a few days creating a fast sudoku solver. However I would like to get everyone's opinion on what constitutes a proper, real sudoku.

The aim of my software mirrors my view on this. It is intended to be an entirely deterministic sudoku solver. By this I only wish to solve sudokus that have exactly 1 solution, given an initial puzzle that contains at least the very bare minimum to achieve the correct solution through logic alone. I am not using any kind of brute-force searching or tables of any kind.

However my other aim is maximum speed (45 microseconds for an easy puzzle on a 1.5ghz celeron, I haven't benchmarked hard puzzles yet but its probably 5 or 6 times slower) and minimum resource usage (my static data structure is about 900 bytes).

To me, a puzzle that has more than one possible solution doesn't really feel 'right'.

What do you guys think about determinism / non-determinism?

Personally I prefer deterministic ones (only 1 solution), not because they are easier but because I value pure algorithmic logic very much. I feel non-deterministic puzzles are a bit unsubtle.

Your view please...
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humble_programmer

Joined: 27 Jun 2006
Posts: 69
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Location: Colorado Springs, USA

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PostPosted: Sat Aug 04, 2007 1:15 pm    Post subject: Reply with quote

By definition, Sudoku puzzles must have a unique solution; if there are multiple solutions, then it's not a Sudoku puzzle.
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Humble Programmer
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vittyken

Joined: 14 Oct 2007
Posts: 6
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Location: Clearwater, FL

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PostPosted: Tue Nov 20, 2007 1:18 pm    Post subject: one sudoku grid-one solution Reply with quote

I am amazed at the Nikoli Sudoku puzzles. They are done by hand and not by a computer.
I would like to learn how to create a one-solution sudoku puzzle.
I therefore agree with you.
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wapati

Joined: 12 Jun 2007
Posts: 622
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Location: Canada

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PostPosted: Tue Nov 20, 2007 9:25 pm    Post subject: Re: one sudoku grid-one solution Reply with quote

vittyken wrote:
I am amazed at the Nikoli Sudoku puzzles. They are done by hand and not by a computer.
I would like to learn how to create a one-solution sudoku puzzle.


Havard, with his brother Erland, created a software to take the tedium out of "man-made" sudoku creation, back in 2005.

http://www.sudoku.frihost.net/

This uses the "fill in" approach. The software tracks the candidates and lets you know when it can solve the puzzle. (Using fairly simple techniques.)


There are two ways to make a puzzle, add givens until you have a puzzle or take givens away from a complete grid, when that is "broken", put some back.

If you go to Havard's website, Deano, the forum moderator, who was building puzzles by hand on paper before he found the easier way, can give very good advice!
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vittyken

Joined: 14 Oct 2007
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Location: Clearwater, FL

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PostPosted: Wed Nov 21, 2007 5:44 am    Post subject: true sudoku puzzle Reply with quote

Thanks for the information. Exactly what I was looking for. It enables me to create and rate a puzzle I can call my own.
Thank you very much.
Very Happy
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wapati

Joined: 12 Jun 2007
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Location: Canada

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PostPosted: Wed Nov 21, 2007 6:40 am    Post subject: Re: true sudoku puzzle Reply with quote

vittyken wrote:
Thanks for the information. Exactly what I was looking for. It enables me to create and rate a puzzle I can call my own.
Thank you very much.
Very Happy


You are very welcome.

Please be aware that "SA" is very helpful but will not be too useful in creating puzzles much past typical newspaper. I do think that it can handle all newspaper puzzles, as of 2007.
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