func_code_string: #include <bits/stdc++.h>   using namespace std;   const int INF = 0x3f3f3f3f;   void solve() {     int m, n;     cin >> n >> m;     vector<long long> v(n);     for (int i = 0; i < n; i++) {       string s;       cin >> s;       for (char c : s) {         v[i] *= 2;         v[i] += c -  0 ;       }     }     long long need = ((1ll << m) - n - 1) / 2 + 1;     long long cur = (1ll << (m - 1)) - 1;     while (true) {       long long left = cur + 1;       bool flag = false;       for (int i = 0; i < n; i++) {         flag |= v[i] == cur;         if (v[i] <= cur) {           left--;         }       }       if (left == need && !flag) {         string s;         for (int i = 0; i < m; i++) {           s += (char)(cur % 2 +  0 );           cur /= 2;         }         reverse(s.begin(), s.end());         cout << s << endl;         return;       } else if (left < need) {         cur++;       } else {         cur--;       }     }   }   int main() {     int t;     cin >> t;     while (t--) {       solve();     }   }   