【題解】Codeforces 1384A. Common Prefixes

#include <iostream>
using namespace std;
 
int t, n, a;
string ans;
 
char f(char x){
    if (x == 'a') return 'b';
    else return 'a';
}
 
int main() {
    cin >> t;
    while (t--){
        cin >> n;
        ans = "";
        for (int i = 0; i < 55; i++){
            ans += "a";
        }
        cout << ans << "\n";
        for (int i = 0; i < n; i++){
            cin >> a;
            ans[a] = f(ans[a]);
            cout << ans << "\n";
        }
    }
}