Help me in solving MAXSCP problem

help
,
1

My issue

include <bits/stdc++.h>
using namespace std;

int main() {
int t = 0;
std::cin>>t;
while(t–)
{
int n = 0;
std::cin>>n;
int sum = 0;
int size = n;
while(n–)
{
std::vectorarr(size);
for(int i=0;i<size;i++)
{
std::cin>>arr[i];
}
std::sort(arr.begin(),arr.end());
sum += arr.at(size-1);
}
std::cout<<sum<<“\n”;
}

}

I want to know why this code is wrong, give me any input for which this approach will fail.

My code

#include <bits/stdc++.h>
using namespace std;

int main() {
	int t = 0;
    std::cin>>t;
    while(t--)
    {
        int n = 0;
        std::cin>>n;
        int sum = 0;
        int size = n;
        while(n--)
        {
            std::vector<int>arr(size);
            for(int i=0;i<size;i++)
            {
                std::cin>>arr[i];
            }
            std::sort(arr.begin(),arr.end());
            sum += arr.at(size-1);
        }
        std::cout<<sum<<"\n";
    }

}

Learning course: Greedy Algorithms
Problem Link: Maximum Score Practice Problem in Greedy Algorithms - CodeChef