 #### Boundary elements are those elements which are not surrounded by elements on all four directions, i.e. elements in first row, first column, last row and last column.

Write a program to accept a matrix of any size from the user an print the sum of the boundary elements of the matrix.

``````import java.util.*;
public class Boundary_Elements
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
int m, n, sum = 0, row1 = 0, col_n = 0, diag = 0;
System.out.print("\nEnter the no. of rows : ");
m = sc.nextInt();
System.out.print("\nEnter the no. of columns : ");
n = sc.nextInt();
int i, j;
int[][] mat = new int[m][n];
System.out.print("\n Input "+ m*n +" matrix elements \n");
for(i = 0; i < m; i++)
{
for(j = 0; j < n; j++)
{
mat[i][j] = sc.nextInt();
}
}
System.out.println("The original matrix is");
for(i = 0; i < m; i++)
{
for(j = 0; j < n; j++)
{
System.out.print(mat[i][j]+ " ");

}
System.out.println();
}
System.out.print("\n Boundary Matrix: \n");
for(i = 0; i < m; i++)
{
for(j = 0; j < n; j++)
{
if (i == 0 || j == 0 || i == n-1|| j == n - 1)
{
System.out.print(mat[i][j] + "  " );
sum = sum + mat[i][j];
}
else
System.out.print("  ");

}
System.out.println( );
}
System.out.print("\n Sum of boundary elements is " + sum);
}
}``````

Output :
Enter the no. of rows : 3
Enter the no. of columns : 3
Input 9 matrix elements
1
2
3
4
5
6
7
8
9
The matrix is
1 2 3
4 5 6
7 8 9
Boundary Matrix
1 2 3
4 6
7 8 9
Sum of boundary elements is 40