Matrix Diagonal Sum.java

class Solution {
    public int diagonalSum(int[][] mat) {
        int sum1 = 0;
        int sum2 = 0;
        int n = mat.length;
        for(int i = 0 ; i < n ; i++)
        {
            sum1 += mat[i][i];
            sum2 += mat[i][n-i-1];
        }
        int res = sum1 + sum2;
        if(n%2 != 0)
        {
            res -= mat[n/2][n/2];
        }
        return res;
    }
}