View Code of Problem 51

#include <stdio.h>
#include <iostream>
#include <string.h>
#include <string>
#include <algorithm>
#include <iomanip>
#include<vector>
#include<math.h>
using namespace std;
int main()
{
	int n;
	int sum = 0;
	cin >> n;
	int a[15][15];
		for (int i = 0; i < n; i++) {
			for (int j = 0; j < n; j++) {
				cin >> a[i][j];
			}
		}
		for (int i = 0; i < n; i++) {
			for (int j = i; j >=0; j--) {
				sum+= a[i][j];
			}
		}
		cout << sum;
}