n
to the length of the matrix (number of rows/columns).ans
to 0 to store the sum of the diagonal elements.i = 0
to i = n - 1
:
mat[i][i]
to ans
(primary diagonal).mat[i][n - 1 - i]
to ans
(secondary diagonal).n
is odd, subtract the central element mat[n / 2][n / 2]
from ans
.ans
.