• + 1 comment

    The real difficulty of this problem is realizing that you can change the value of any cell of the first quarter submatrix for any of the other 3 options available without affecting any other value of the first quarter submatrix.

    This can be achieved with a flipping sequence like this:

    The other 2 candidate cells can be moved to the first quarter submatrix using the same sequence as above after using this second sequence: