I am writing a program that will solve the sudoku puzzle I am using a 2d array instead of a 3d array to set up the grid and am wondering, because I did this, would the best way to test for duplicates in a subgrid be setting up a 3x3 matrix and test within that. Or is there another way that I cant think of that I could research.

This is homework so plz do not post any answers for me(cant believe I am writing This). just ideas that I can try to figure out on my own. I am just starting out and would like to legitimately learn this language. thx.