public class Solution { public int diagonalSum(int[][] mat) { int primarySum = 0; for (int i = 0; i < mat.length; i++) { primarySum+= mat[i][i]; } int secondarySum = 0; for (int i = 0; i < mat.length; i++) { secondarySum+= mat[i][mat.length-1-i]; } if (mat.length%2==0){ return primarySum+secondarySum; } else { int mid = mat.length/2; return primarySum+secondarySum- mat[mid][mid]; } } }