View Code of Problem 51

#include<algorithm>
#include<cstdio>
#include<cmath>
#include<string>
#include<cstring>
#include<iostream>
#include<vector>

using namespace std;

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