With a given matrix A (size m x n) create a matrix B (size m+2 x n+2) so that the matrix A is surrounded by ones:
A = [1 2 3
3 2 1]
B = [1 1 1 1 1
1 1 2 3 1
1 3 2 1 1
1 1 1 1 1]
or
A = 4
B = [ 1 1 1
1 4 1
1 1 1]
Additional test cases have been added.
nice way to learn about matrix concatenation