Language: C++

#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cmath>
#include<cstring>
#include<vector>
#include<ctime>
typedef long long ll ;
#define rep(i, a, b) for (int i = a; i <= b; ++i)
using namespace std;


string s;
int k;
const int MAXN = 50000;
const int MAXK = 6;
string x[MAXK], sx;


int main() {
	cin >> s >> k;
	rep(i, 0, s.length() - 1) {
		rep(j, i, min(i + 6, s.length() - 1)) {
			sx.clear();
			sx = s.substr(i, j - i + 1);
			bool tf = 1;
			rep(i, 1, k) {
				if (x[i] == sx) tf = 0;
			}
			if (tf && sx < x[k] || x[k].length() <= 0) {
				int kx = k;
				while (x[kx].empty() && kx > 1) --kx;
				if (!x[kx].empty() && kx < k) ++kx;
				x[kx] = sx;
				sort(x + 1, x + 1 + kx);
			}
		}
	}
	cout << x[k] << "\n";
	return 0;
} 


Compiler output:
a.cc: In function 'int main()':
a.cc:23:30: error: no matching function for call to 'min(int, std::__cxx11::basic_string<char>::size_type)'
   23 |                 rep(j, i, min(i + 6, s.length() - 1)) {
      |                           ~~~^~~~~~~~~~~~~~~~~~~~~~~
a.cc:9:43: note: in definition of macro 'rep'
    9 | #define rep(i, a, b) for (int i = a; i <= b; ++i)
      |                                           ^
In file included from /usr/include/c++/14/string:51,
                 from /usr/include/c++/14/bits/locale_classes.h:40,
                 from /usr/include/c++/14/bits/ios_base.h:41,
                 from /usr/include/c++/14/ios:44,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_algobase.h:233:5: note: candidate: 'template<class _Tp> constexpr const _Tp& std::min(const _Tp&, const _Tp&)'
  233 |     min(const _Tp& __a, const _Tp& __b)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:233:5: note:   template argument deduction/substitution failed:
a.cc:23:30: note:   deduced conflicting types for parameter 'const _Tp' ('int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'})
   23 |                 rep(j, i, min(i + 6, s.length() - 1)) {
      |                           ~~~^~~~~~~~~~~~~~~~~~~~~~~
a.cc:9:43: note: in definition of macro 'rep'
    9 | #define rep(i, a, b) for (int i = a; i <= b; ++i)
      |                                           ^
/usr/include/c++/14/bits/stl_algobase.h:281:5: note: candidate: 'template<class _Tp, class _Compare> constexpr const _Tp& std::min(const _Tp&, const _Tp&, _Compare)'
  281 |     min(const _Tp& __a, const _Tp& __b, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:281:5: note:   candidate expects 3 arguments, 2 provided
In file included from /usr/include/c++/14/algorithm:61,
                 from a.cc:3:
/usr/include/c++/14/bits/stl_algo.h:5686:5: note: candidate: 'template<class _Tp> constexpr _Tp std::min(initializer_list<_Tp>)'
 5686 |     min(initializer_list<_Tp> __l)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5686:5: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_algo.h:5696:5: note: candidate: 'template<class _Tp, class _Compare> constexpr _Tp std::min(initializer_list<_Tp>, _Compare)'
 5696 |     min(initializer_list<_Tp> __l, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5696:5: note:   template argument deduction/substitution failed:
a.cc:23:30: note:   mismatched types 'std::initializer_list<_Tp>' and 'int'
   23 |                 rep(j, i, min(i + 6, s.length() - 1)) {
      |                           ~~~^~~~~~~~~~~~~~~~~~~~~~~
a.cc:9:43: note: in definition of macro 'rep'
    9 | #define rep(i, a, b) for (int i = a; i <= b; ++i)
      |                                           ^