func_code_string: #include <bits/stdc++.h>   using namespace std;   void solve() {     int n;     cin >> n;     string s;     cin >> s;     string ans =   ;     int cnt = 0;     for (int i = n - 1; i >= 0; i--) {       if (s[i] ==  1 ) {         if (cnt > 0) {           while (i >= 0 && s[i] ==  1 ) i--;           cnt = 1;           i++;         } else           ans +=  1 ;       } else {         cnt++;       }     }     while (cnt--) ans +=  0 ;     reverse(ans.begin(), ans.end());     cout << ans << endl;   }   int main() {     ios_base::sync_with_stdio(false);     int t;     cin >> t;     while (t--) solve();   }   