problem code-DECSTR

what is wrong in this solution?
#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef long int l;

int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
l t;
cin>>t;
while(t–)
{
int n;
cin>>n;
string s="";
int k=n/26;
int i;
if(n==0)
cout<<" "<<endl;
else{
for(i=0;i<=n;i++)
{
s+=((i%26)+‘a’);
}
for(int j=0;j<k;j++)
{
s+=((i%26)+‘a’);
i++;
}
reverse(s.begin(),s.end());
cout<<s<<endl;}
}
return 0;
}

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