View Code of Problem 51

#include <iostream>
#include <string>

using namespace std;

int main() {
    int n,sum=0;
    int a[10][10];
    cin>>n;
    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 = 0; j <= i; ++j) {
            sum=sum+a[i][j];
        }
    }
    cout<<sum<<endl;
    return 0;
}