create a double dimension array of size m x n, where m and n are input by the user and calculate the sum of the border elements.

Border elements of an array are placed at the border of the array. Which are satisfy some conditions (i)if row no = 0 or (total row -1) (ii) column no = 0 or (total col -1). Therefore, we just travel the array once and add all the elements which meet the above conditions.

import java.util.*;
public class Border2D
{
    public static void main(String []args)
    {
        Scanner sc=new Scanner(System.in);
        int s=0,m,n;
        System.out.print("Enter the Row No :");
        m=sc.nextInt();
        System.out.print("Enter the Col No :");
        n=sc.nextInt();
        
        int [][]arr=new int[m][n];
        
        for(int r=0;r<m;r++)
        {
            for(int c=0;c<n;c++)
            {
                arr[r][c]=sc.nextInt();
                
            }
        }
        for(int r=0;r<m;r++)
        {
            for(int c=0;c<n;c++)
            {
                if((r==0) || (r==(m-1)) || (c==0) || (c==(n-1)))  
                {
                    s+=arr[r][c];
                }
            }
        }
        System.out.println("Sum Is : " + s);
    }
}