#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int main(void)
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    ll t;
    cin >> t;
    while (t--)
    {
        ll n;
        cin >> n;
        ll a[n + 1] = {0},b[n+1]={0},c[n+1]={0};
        map<ll, ll> mp;
        map<ll, ll> p;
        for (ll i = 1; i <= n; i++)
        {
            cin >> a[i];
            b[a[i]]=i;
        }
        for(ll i=1;i<=n;i++)
        {
            if(a[i]==i)
                cout<<i;
        }
        for(ll i=1;i<=n;i++)
        {
            if(a[i]!=i&&c[i]==0)
            {
                cout<<i;
                c[i]=1;
                if(c[b[i]]==0)
                {
                    cout<<b[i];
                    c[b[i]]=1;
                }
            }
        }
        cout<<'\n';
    }
}