Language: C++

#include <iostream>
#include <algorithm>
#include <vector>
#include <queue>
#include <map>
#include <set>
#include <iomanip>
#include <cmath>
using namespace std;
#define REP(i,n) for (int i=0;i<(n);++i)
#define rep(i,a,b) for(int i=a;i<(b);++i)
constexpr int INF = 1 << 30;
constexpr int MOD = 1e9 + 7;

int n;
string s;


vector<int> z_algorithm(const string &s) {
  int n = (int)s.size();
  vector<int> a(n);

  a[0] = n;
  int i = 1, j = 0;
  while (i < n) {
    while (i + j < n && s[j] == s[i+j]) ++j;
    a[i] = j;
    if (j == 0) { ++i; continue;}
    int k = 1;
    while (i+k < n && k+a[k] < j) a[i+k] = a[k], ++k;
    i += k; j -= k;
  }
}

int main() {
  cin.tie(0); ios_base::sync_with_stdio(false);
  cin >> n >> s;

  long ans = 0;
  for(int i = 0; i < n; ++i) {
    auto res = z_algorithm(s);
    for(int i = 1; i < (int)res.size(); ++i) {
      ans = max(ans, min(i, res[i]));
    }
  }

  cout << ans << endl;
  return 0;
}

Compiler output:
a.cc: In function 'std::vector<int> z_algorithm(const std::string&)':
a.cc:33:1: warning: no return statement in function returning non-void [-Wreturn-type]
   33 | }
      | ^
a.cc: In function 'int main()':
a.cc:43:16: error: no matching function for call to 'max(long int&, const int&)'
   43 |       ans = max(ans, min(i, res[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: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:43:16: note:   deduced conflicting types for parameter 'const _Tp' ('long int' and 'int')
   43 |       ans = max(ans, min(i, res[i]));
      |             ~~~^~~~~~~~~~~~~~~~~~~~~
/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:2:
/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:43:16: note:   mismatched types 'std::initializer_list<_Tp>' and 'long int'
   43 |       ans = max(ans, min(i, res[i]));
      |             ~~~^~~~~~~~~~~~~~~~~~~~~