Language: C++

#include<iostream>
#include<vector>
#include<algorithm>
#include<string>
#include<cmath>

using namespace std;

typedef long long ll;

ll N, K;
ll P[5000 + 10], C[5000 + 10];

int main() {
	//No sub撤退しないぞ
	cin >> N >> K;
	for (int i = 0; i < N; i++) {
		cin >> P[i];
		P[i]--;
	}
	for (int i = 0; i < N; i++) {
		cin >> C[i];
	}

	ll ans = -100000000000000000;
	for (int i = 0; i < N; i++) {
		//iからスタート
		vector<ll> res;
		vector<bool> visited(N);
		int nw = i;
		int cnt = 0;
		while (true) {
			if (visited[P[nw]])break;
			res.push_back(0);
			visited[P[nw]] = true;
			nw = P[nw];
			if (cnt == 0)res[cnt] = 0 + C[nw];
			else res[cnt] = res[cnt - 1] + C[nw];
			cnt++;
		}
		if (K <= cnt) {
			ll tmp = -100000000000000000;
			for (int j = 0; j < K; j++) {
				tmp = max(tmp, res[j]);
			}
			ans = max(tmp, ans);
		}
		else {
			ll tmp = -100000000000000000;
			for (int j = 0; j < (K % res.size()); j++) {
				tmp = max(tmp, res[j]);
			}
			ans = max(ans, tmp + max(0LL, res.back()) * (K / res.size()));
		}
	}
	cout << ans << endl;
	return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:53:34: error: no matching function for call to 'max(ll&, long long unsigned int)'
   53 |                         ans = max(ans, tmp + max(0LL, res.back()) * (K / res.size()));
      |                               ~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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:257:5: note: candidate: 'template<class _Tp> constexpr const _Tp& std::max(const _Tp&, const _Tp&)'
  257 |     max(const _Tp& __a, const _Tp& __b)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:257:5: note:   template argument deduction/substitution failed:
a.cc:53:34: note:   deduced conflicting types for parameter 'const _Tp' ('long long int' and 'long long unsigned int')
   53 |                         ans = max(ans, tmp + max(0LL, res.back()) * (K / res.size()));
      |                               ~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algobase.h:303:5: note: candidate: 'template<class _Tp, class _Compare> constexpr const _Tp& std::max(const _Tp&, const _Tp&, _Compare)'
  303 |     max(const _Tp& __a, const _Tp& __b, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:303:5: 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:5706:5: note: candidate: 'template<class _Tp> constexpr _Tp std::max(initializer_list<_Tp>)'
 5706 |     max(initializer_list<_Tp> __l)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5706:5: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_algo.h:5716:5: note: candidate: 'template<class _Tp, class _Compare> constexpr _Tp std::max(initializer_list<_Tp>, _Compare)'
 5716 |     max(initializer_list<_Tp> __l, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5716:5: note:   template argument deduction/substitution failed:
a.cc:53:34: note:   mismatched types 'std::initializer_list<_Tp>' and 'long long int'
   53 |                         ans = max(ans, tmp + max(0LL, res.back()) * (K / res.size()));
      |                               ~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~