这道华为机试有点奇怪，求解

#include<iostream>
#include<vector>
using namespace std;

int main()
{
while (cin) {
vector<int> voltage(10, 0);
for (int i = 0; i < 10; ++i)
cin >> voltage[i];
vector<int> avg;
for (int i = 0,sum = 0, j = 0; i < 10; ++i) {
if (voltage[i] >= 3300 && voltage[i] <=
    4200) {
sum += voltage[i];
++j;
}
if (j == 5) {
avg.push_back(sum / 5);
sum = 0;
j = 0;
}
}
cout << avg.size();
for (int i = 0; i < avg.size(); ++i)
cout << " " << avg[i];
cout << endl;
}
return 0;
}