Sum of Boundary Diagonals

This program calculates sum of both diagonals of a matrix.

Problem Statement

Write a Java program to calculate sum of both diagonals of a 4x4 matrix.

Source Code

1 public class MatrixBoundaryDiagonalSum {
2 public static void main(String[] args) {
3 System.out.println("Eduinq Matrix Boundary Diagonal Sum");
4 int[][] A = {
5 {1,2,3,4},
6 {5,6,7,8},
7 {9,10,11,12},
8 {13,14,15,16}
9 };
10 int sum=0;
11 for(int i=0;i<4;i++){
12 sum+=A[i][i];
13 sum+=A[i][4-1-i];
14 }
15 System.out.println("Sum of both diagonals = "+sum);
16 }
17 }

Program Output

Eduinq Matrix Boundary Diagonal Sum
Sum of both diagonals = 68

Explanation

Main diagonal elements are accessed as A[i][i] and secondary diagonal elements as A[i][n-1-i], and a single loop adds both into sum, together calculating the combined boundary diagonal sum.

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