View Code of Problem 51

import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);
		int n =sc.nextInt();
		int matrix[][] = new int[n][n];
		for(int i=0;i<matrix.length;i++) 
		{
			for(int j=0;j<matrix.length;j++)
				matrix[i][j] = sc.nextInt();
		}
		System.out.println(cal(matrix));
	}
	static int cal(int[][] matrix) 
	{
		int sum = 0;
		for(int i=0;i<matrix.length;i++)
			for(int j=0;j<i+1;j++)
				sum+=matrix[i][j];
		return sum;
	}
}