B_Following_the_String.cpp

#include <bits/stdc++.h>
#define read(type) readInt<type>() // Fast read
#define int long long
#define endl "\n"
#define pb push_back
#define eb emplace_back
#define mk make_pair
#define pii pair<int, int>
#define F first
#define S second
#define vi vector<int>
#define all(x) (x).begin(), (x).end()
#define umap unordered_map
#define uset unordered_set
#define MOD 1e9 + 7
#define imax INT_MAX
#define imin INT_MIN
#define exp 1e9
#define sz(x) (int((x).size()))
using namespace std;

signed main(void) {
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    int n,x,a; cin >> n;
    while(n--) {
        map<int, int> mp;
        cin >> x;
        for(int i = 0; i < x; ++i) {
            cin >> a;
            cout << (char)('a' + mp[a]);
            mp[a]++;
        }
        cout << endl;
    }
}