Just read the rules for Sudoku.
You can develop your own program.
The rules pretty much give you the things you need to create your
start with the nice article at wikipedia
You could do it many ways, but consider multi-dimensional arrays or
These correspond well to a grid. 3 x 3, each containing a 3 x 3 grid.
Make sure that any given row or column follows the rules.
You could get more creative to speed your generation times:
Generate first a list of the sub-grids, there is a finite number of
them. Label each one.
Perhaps use a label that is descriptive of the contents, very simply:
123456789, or 235149876
as an example if you read each subgrid from left to right, starting
in the top right
another method would be to give each combination of 3 digits from 1-9
some sort of symbolic label.
Then assign 6 of these to each sub grid (3 horizontal, 3 vertical)
Anyway, once you have each sub-grid it becomes very simple to develop
matching/not matching combinations.
Now the hard part is deciding which numbers to reveal or leave hidden
and yet keep the puzzle solveable!