Sudoku solver that returns more than one solution

barleyfarmer

A UK satellite channel put up a massive sudoku board in the UK somewhere near Bristol that is carved into a chalk hillside.

Unfortunately, it gives more than one solution;

506020903
008000500
000000000
600285009
000903000
800761004
000000000
004000300
201050607

1,905 - apparently, it was tested with some free software on the web and it came back with only one solution. I noted that the free solver on this site said the puzzle was unique. Oooops.

I like a combination of brute-force and heuristics, in fact I have two programs, one for each. The heuristics based one finds a solution in "spring-time" i.e. the time it takes for the spring to push up the Enter key. The brute force one took under 3 mins to shove out all 1,905 permutations.

Sad, as it may seem, I still use a pencil, rubber and grey matter. The programming is just for fun.

BTW:My phone call to the channel concerned was "Ummm, we'll call you back..." they never did. Probably thought I was a crank...

Steve Wink

Simes · Posted: Wed Jul 13, 2005 7:09 am Post subject:

Hi Steve,

You've already seen my solver, but did you notice that it can first count, and then show all solutions?
_________________
Simes
www.sadmansoftware.com/sudoku

barleyfarmer · Posted: Wed Jul 13, 2005 9:01 am Post subject:

Yes, thanks, the program works very well. It's the best of the 10 I tried and the only one to prove an incorrect sudoku, e.g. Sky's hillside blunder.

abik · Posted: Sat Sep 10, 2005 5:45 am Post subject:

I can confirm the number of different solutions, found in about 4 milliseconds with a backtracking solver in C.

dukuso · Posted: Sat Sep 10, 2005 6:47 am Post subject:

ssubbanna

I have a couple of Sudokus that have more than one correct soluytion .Can I post them ? If so, please let me know.. how.
Thank you Sir
Ssubbanna
Bangalore
India

abik · Posted: Thu Sep 22, 2005 4:39 pm Post subject: multi solutions

Why don't you join the discussion in the nodes-per-second thread in this same forum? Post your puzzles any place on the Web where we can download them. Use a commonly used format such as a file with lines of 81 characters 0..9 where each puzzle starts at a new line. An example with two puzzles follows.