I'm trying to create a Sudoku puzzle generator in php. As I got deeper, I found that this is not an easy-as-I-guessed thing to do. So I have divided the problem into two parts,
- Getting a complete (solved) sudoku
- Removing some numbers from it, so that it remains a puzzle that has only one solution.
So, for step 2, what kind of algorithm should I use in order to "puzzlize" a solved sudoku?
I could also use help in step 1, since I'm using bruteforce methods, and I'm facing running time issues.