Determinant

1. Enhance your previous exercise of CMatrix by adding a member function Det() so that it can calculate the determinant of a matrix.
2. Hint: It will be useful to define a helper function CMatrix Minor(int i, int j) to derive the minor of matrix A by eliminating row i and column j from A. With this function, it becomes straightforward to calculate the determinant with a recursive formula.

int main()
{
    int n;

    cin >> n;
    CMatrix a(n,n);
    a.Read();
    cout << a.Det() << endl;

    return 0;
}  

1. For the input

   2
   1 2
   3 4  

   The running result should be

   -2  

2. For the input

   3
   1 0 0
   0 2 0
   0 0 3  

   The result should be

   6