im new here. Im developing a c program. pls help

detective_mark7

hi, im currently developing a c program sudoku solver that simulates how i think. my program (and me) cannot solve this sudoku:

268 268 9 158 28 125 4 7 3
5 278 3 489 24789 279 89 6 1
1 78 4 3 6 79 2 89 5
49 159 6 7 35 8 19 239 24
7 3 2 149 49 19 6 5 8
489 1589 15 2 35 6 179 39 47
3 256 7 68 1 4 58 28 9
29 1259 15 89 2789 3 578 4 6
269 4 8 569 279 2579 3 1 27
*when there are multiple numbers, it means the numbers are the possible values for that cell

the thing is I don't know all the solving techniques. would someone could kindly pls show me the next step or tell me what technique/s i didnt implement.

thanks

PS. Rybka 3 is so cool.

hobiwan · Posted: Thu Oct 30, 2008 7:55 pm Post subject:

Hello detective_mark7,

the first available step is a naked triple:

Naked Triple: 2,6,8 in r1c125 => r1c4<>8, r1c6<>2

but you will need some advanced techniques to solve this puzzle (XY-Chains (or other sorts of chains like AIC or Nice Loops) and Wings (XY-Wing, XYZ-Wing, W-Wing)).

I don't really know how much techniques you have already implemented, but since your solver doesn't get the naked triple, I would start with an easier puzzle Very Happy

.

A very good source for the various solving techniques is Sudopedia. Techniques for newspaper like puzzles would be hidden/naked subsets and locked candidates.

Hope that helps

detective_mark7 · Posted: Sun Nov 02, 2008 3:37 am Post subject:

thanks

i have included naked triple and some other algorithms in my program.
and this is the result:

0 0 9 0 0 0 4 7 3
5 0 3 0 0 0 0 6 1
1 0 4 3 6 0 2 0 5
0 0 6 7 0 8 0 0 0
7 3 2 0 0 0 6 5 8
0 0 0 2 0 6 0 0 0
3 0 7 0 1 4 0 0 9
0 0 0 0 0 3 0 4 6
0 4 8 0 0 0 3 1 0

268 268 num 15 28 15 num num num
num 278 num 489 24789 279 89 num num
num 78 num num num 79 num 89 num

49 159 num num 35 num 19 239 24
num num num 149 49 19 num num num
489 1589 15 num 35 num 179 39 47

num 256 num 68 num num 58 28 num
29 1259 15 89 2789 num 578 num num
269 num num 569 279 2579 num num 27

then i read about cages and wings in sudopedia and decided it was hard program.

thanks anyway.

solvedoku · Posted: Sun Nov 02, 2008 3:47 am Post subject:

thats the spirit!!!

pb · Posted: Sun Jan 11, 2009 12:24 pm Post subject:

Actually you will always have to use brute-force as the last resort in some cases. In my javascript solver I just use a few basic techniques (those I haven't been lazy to implement yet) and when I see I can't do anymore, I just use brute-force. Even the hardest puzzles get solved in a few secs.
--
p.

kayanat

What is a good way to improve my sudoku-solving skills? All my friends are fantastic at sudoku and they LOVE it, but i don't, mainly because well, I can't solve those things. I just want to know for those sudoku solvers out there how do you solve them, is it natural ability, patience, or secret formula that I don't know about...? Thanks.

Adak · Posted: Fri Apr 10, 2009 4:45 am Post subject:

I suggest going to the Sudoku Player's Forum, and reading (studying) up. Sure, there are a lot of techniques to help solve the puzzle, and of course, natural aptitude is a factor.

But a lot of it is just simple practice, and learning various techniques, and then practicing even more.

I read an interview with the new Sudoku solver World Champion, and I had to chuckle, because he was practicing so much, it was insane. Shocked

Persistence in your study and practice, go a LONG way.

ivoc