# Sudoku: Multiple solutions

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Mozza314
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Last seen: 16 years 7 months ago
Joined: 2008-01-06 17:51
Sudoku: Multiple solutions

Initial numbers give multiple solutions.

Hi. I decided to try playing some sudoku the other day, got quite a bit into and decided to play a few games on the 'hard' difficulty. Anyway, I got stuck, so I decided to make a guess and draw in successive numbers lightly to see if I could find a contradiction. Bafflingly, I didn't find a contradiction and got stuck again, so I made another guess. Anyway, I ended up finding a valid solution, checked it on the paper copy I was using and entered it into the program and it lit up green. Problem is, there were two valid ways of solving it. Worse still, I tried restarting the game and do an automatic solve, and it gave me yet another solution. This is bad, there must only be one valid solution compatible with the initial numbers in a game of sudoku. I took screenshots of the initial game numbers (top-left), the automatic solve (bottom-left) and my two solutions (right). The differences between my two solutions is very small, I've put red circles around the differences in the bottom-left grid.

Unfortunately these forums won't let me put an image in the post. Here's a direct link to it on photobucket:
http://i169.photobucket.com/albums/u236/Mozza314/sudokuTroubles.gif

Tim Clark
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Last seen: 13 years 4 months ago
Joined: 2006-06-18 13:55
Limitation not Bug

I believe I recall reading somewhere that this is a known limitation of the program. Its program logic does not require the creation of a puzzle that can only have one solution.

You would need to contact the creator of the program as all that is done here at PA.com is that the program is "portablized"

Tim

{edit: If you had browsed the Sudoko forum before posting you would have found this:
Every Sudoku has one solution... I found two...
https://portableapps.com/node/2890 }

Things have got to get better, they can't get worse, or can they?

Mozza314
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Last seen: 16 years 7 months ago
Joined: 2008-01-06 17:51
Looked back at the info and

Looked back at the info and found that it said some of the 'hard' puzzles will have more than one solution... so I guess it's not really a bug. Still, that's really bad for a sudoku game.

Wylie Coyote
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Last seen: 16 years 6 months ago
Joined: 2008-01-17 03:37
I don't think it is just the

I don't think it is just the Hard level.
I have played a few quick games on 'medium' and there have been more than one solution.
I had a paper (yeah, really) sudoku book that was like this and found it very frustrating.
You shouldn't be able to just guess a solution ...

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