First you start by reading up on the
Sudoku solving algorithm, then you considder it as a
Boolean satisfiability problem, then you realise you can solve it by using some clever
Matrices algorithms, but don't fall into the trap of making the solution too
difficult.
In the end you'll come up with some form of solution which isn't perfect and you will come here with some code fragments asking us how to solve your emidiate problem with that.
In the end you'll make all of us happy (your self included) by not demanding solving a homework assignment, but rather providing you with help which will make you clever enough to think for yourself.