I came across this question online stated being asked in some company’s test. It’s like this:

You are given a 9x9 grid, a filled sudoku but there are some error in it, there may be max 3 digits in-correctly filled in the sudoku grid (i.e.there may be 1 , 2, or 3 errors in sudoku filling). You have to device a computer program that detects those errors in the sudoku and places the correct digits(1-9) at those wrong filled cells of the sudoku.

Output should be in the form : place in the grid where there is an error in the sudoku and the correct digit to be placed there to make the sudoku correct.

I could not find any such kind of solution online, so asking out for help here. Please someone help how to solve such a problem.