I'm a student of POLITECNICO DI TORINO. I write to you for a study case about the givens of sudoku. I have to build a proper Sudoku puzzle, I need to derive an initial grid such that there exists a feasible Sudoku solution compatible to that grid and this solution is unique. This work require further the practice of SIMULATED ANNEALING and the kind of sudoku is SIMMETRIC, with Xpress-IVE programm. I konw that this isn’t the best way to solve the problem,but this is my study case and I have to comment the result. Anybody know something to help me? I surfed on the web,but I don’t found any!! Please help me Thank you in advance

Have you tried generating a completed board and then removing numbers until you've got an initial puzzle? Starting from a completed board guarantees that you'll produce a solvable puzzle - but not neccesarily that the initial solution will be the only possible solution.

Just solve a sudoku puzzle from like a book, and remove randomn numbers.

Very interesting....
I did this sudoku thing to pass time. I wrote a small C program that solves the sudoku puzzle. I got stuck trying to generate an initial grid to solve.
I hope you find a way to generate that grid. I gave up because I had to keep working on my game.
Good luck!

At this page you can find a possible solution to your problem:

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dntablet/html/tbconsudokusamplefinal.asp

It's quite a long read, but if you click the Sudoku Algorithms link in the Contents, it will take you to the part you're interested in.

Hope this helps.

How many initial points do you have to provide? If this is a homework assignment, randomly place a number (1 thru 9) on any of the squares, and call it a night.

Quote:

Original post by Cygnus_X How many initial points do you have to provide? If this is a homework assignment, randomly place a number (1 thru 9) on any of the squares, and call it a night.

I have to found the way to generate the initial grid of sudoku, if the initial grid contains a few digits it's better.

I have only one constriction: the initial grid that I find must have only one solution (resolving the sudoku).

Quote:

Original post by etim At this page you can find a possible solution to your problem: http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dntablet/html/tbconsudokusamplefinal.asp It's quite a long read, but if you click the Sudoku Algorithms link in the Contents, it will take you to the part you're interested in. Hope this helps.

thank you!!!

I hope to find something of interesting...

Start with a completed sudoku and start removing numbers. In order to keep symmetry remove pairs. After each removal step, check whether it is unique. Repeat.

Quote:

Original post by Thermodynamics Start with a completed sudoku and start removing numbers. In order to keep symmetry remove pairs. After each removal step, check whether it is unique. Repeat.

This won't exactly work too well.

Rather, you could reverse it. (You would want to start with an empty board and start adding numbers, not removing them.) By removing, a completed sudoku would always return as unique with the first number you removed.

*Edit*

Also, fewer numbers doesn't necessarily make a sudoku harder. You would want to get into a situation where to know what number you can place down, you would have to go more steps into the future to see what number could be eliminated.