View Code of Problem 51

#include<iostream>
#include<vector>
#include<string>
#include <algorithm>
#include <math.h>
using namespace std;


int main() {
    int n;
    cin >> n;
    int a[n][n];
    for(int i=0; i<n; i++){
        for(int j=0; j<n; j++){
            cin >> a[i][j];
        }
    }
    int sum = 0;
    for(int i=0; i<n; i++){
        for(int j=0; j<=i; j++){
            sum += a[i][j];
        }
    }

    cout << sum;

}