func_code_string: #include <bits/stdc++.h>   using namespace std;   const long long M = 1e9 + 7;   const long long INF = LLONG_MAX / 2;   const long long N = 1e4;   signed main() {     ios_base::sync_with_stdio(0);     cin.tie(0);     cout.tie(0);     long long t;     cin >> t;     while (t--) {       long long n, k;       cin >> n >> k;       string s;       cin >> s;       sort(s.begin(), s.end());       char last = s[n - 1];       vector<string> a(k);       for (long long i = 0; i < k; i++) a[i].append(1, s[i]);       long long i = k, j = 0;       if (count(a.begin(), a.end(), a[0]) == k && s[i] == last)         while (i < n) {           a[j % k].append(1, s[i]);           i++;           j++;         }       else         a[j].append(s.substr(k, n - k));       cout << *max_element(a.begin(), a.end()) <<   n ;     }     return 0;   }   