func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     ios::sync_with_stdio(false);     cin.tie(0);     cout.tie(0);     int T;     cin >> T;     while (T--) {       int n, k;       cin >> n >> k;       string s;       cin >> s;       sort(s.begin(), s.end());       if (s[k - 1] != s[0]) {         cout << s[k - 1] << endl;       } else {         if (s[n - 1] != s[k]) {           string tmp =   ;           tmp += s[0];           for (int i = k; i < n; i++) {             tmp += s[i];           }           cout << tmp << endl;         } else {           int tmp = (n - k - 1) / k + 1;           string tmp2 =   ;           tmp2 += s[0];           for (int i = 0; i < tmp; i++) {             tmp2 += s[k];           }           cout << tmp2 << endl;         }       }     }   }   