func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     ios_base::sync_with_stdio(false);     cin.tie(NULL);     cout.tie(NULL);     int t;     cin >> t;     while (t--) {       long long int n, z = 0, o = 0;       cin >> n;       string s;       cin >> s;       if (n == 1) {         cout << s << endl;         continue;       }       for (long long int i = 0; i < n; i++) {         if (s[i] ==  0 )           z++;         else           break;       }       z++;       for (long long int i = n - 1; i >= 0; i--) {         if (s[i] ==  1 )           o++;         else           break;       }       if (o + z == n + 1) {         cout << s << endl;         continue;       }       while (z) {         cout <<  0 ;         z--;       }       while (o) {         cout <<  1 ;         o--;       }       cout << endl;     }   }   