func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int t;     cin >> t;     while (t--) {       string str;       int n;       cin >> n;       cin.ignore();       getline(cin, str);       int l = 0, r = n - 1;       while (l < n && str[l] ==  0 ) {         l++;       }       while (r >= 0 && str[r] ==  1 ) {         r--;       }       if (l >= r) {         cout << str << endl;       } else {         cout << str.substr(0, l) <<  0  << str.substr(r + 1, n) << endl;       }     }     return 0;   }   