参考答案：

#include <iostream>
#include <string>
using namespace std;
char s[10];
int main()
{
    int t;
    cin >> t;
    int n;
    while (t--)
    {
        cin >> n;
        while (n)
        {
            int a;
            scanf("%5d", &a);
            s[0] = a / 26 / 26 + 'a';
            s[1] = a / 26 % 26 + 'a';
            s[2] = a % 26 + 'a';
            n -= 5;
            cout << s;
        }
        cout << endl;
    }
    return 0;
}