A matrix is a two-dimensional array with the same number of rows and columns.

We can define the identity matrix to be a two-dimensional array that has the main diagonal (running from the northwest to the southeast) with all ones, and zero values everywhere else.

Write a complete Java method named ident that returns such an identity matrix, given a single int argument, n (which specifies the number of rows and columns). You may assume the array will contain int values only.

Thus, ident(4) would return a 2D array that contains

1000

0100

0010

0001