MatrixDiagonalSum.java

import java.util.Arrays;
import java.util.function.BiFunction;

//E
//Given a square matrix mat, return the sum of the matrix diagonals.
//Only include the sum of all the elements on the primary diagonal and all the elements on the secondary diagonal that are not part of the primary diagonal.
//Example:
//        Input: mat = [[1,2,3],
//        [4,5,6],
//        [7,8,9]]
//        Output: 25
//        Explanation: Diagonals sum: 1 + 5 + 9 + 3 + 7 = 25
//        Notice that element mat[1][1] = 5 is counted only once.
public class MatrixDiagonalSum {
    public int diagonalSum(int[][] mat) {
        int sum=0;
        for(int i=0;i<mat.length;i++)
        {
            sum+=mat[i][i];
            sum+=mat[i][mat.length-i-1];
        }
        if(mat.length%2!=0)
        {
            sum-=mat[(int) Math.floor(mat.length/2)][(int) Math.floor(mat.length/2)];
        }
        return sum;
    }
}