Language: C++

#include<bits/stdc++.h>
using namespace std;
int main(){
  int n;
  long long k;
  cin>>n>>k;
  vector<int> a(n);
  for(int i=0;i<n;i++){
    cin>>a[i];
  }
  vector<int> b;
  vector<int> c(n+1);
  map<int,int> map;
  int now=1;
  int s=0,t=0;
  for(int i=0;i<n;i++){
    t.push_back(now);
    c[now]=1;
    map[now]=i;
    now=a[now-1];
    if(1==c[now]){
      a=map[now];
      break;
    }
  }
  b=t.size()-1;
  int ret=-1;
  if(k<(long long)t.size()){
    ret=b[k];
  }
  else{
    long long c=(k-s)%(t)+s;
    ret=b[c];
  }
  cout<<ret<<endl;
  return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:17:7: error: request for member 'push_back' in 't', which is of non-class type 'int'
   17 |     t.push_back(now);
      |       ^~~~~~~~~
a.cc:22:16: error: no match for 'operator=' (operand types are 'std::vector<int>' and 'std::map<int, int>::mapped_type' {aka 'int'})
   22 |       a=map[now];
      |                ^
In file included from /usr/include/c++/14/vector:72,
                 from /usr/include/c++/14/functional:64,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:53,
                 from a.cc:1:
/usr/include/c++/14/bits/vector.tcc:210:5: note: candidate: 'std::vector<_Tp, _Alloc>& std::vector<_Tp, _Alloc>::operator=(const std::vector<_Tp, _Alloc>&) [with _Tp = int; _Alloc = std::allocator<int>]'
  210 |     vector<_Tp, _Alloc>::
      |     ^~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/vector.tcc:211:42: note:   no known conversion for argument 1 from 'std::map<int, int>::mapped_type' {aka 'int'} to 'const std::vector<int>&'
  211 |     operator=(const vector<_Tp, _Alloc>& __x)
      |               ~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
In file included from /usr/include/c++/14/vector:66:
/usr/include/c++/14/bits/stl_vector.h:766:7: note: candidate: 'std::vector<_Tp, _Alloc>& std::vector<_Tp, _Alloc>::operator=(std::vector<_Tp, _Alloc>&&) [with _Tp = int; _Alloc = std::allocator<int>]'
  766 |       operator=(vector&& __x) noexcept(_Alloc_traits::_S_nothrow_move())
      |       ^~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:766:26: note:   no known conversion for argument 1 from 'std::map<int, int>::mapped_type' {aka 'int'} to 'std::vector<int>&&'
  766 |       operator=(vector&& __x) noexcept(_Alloc_traits::_S_nothrow_move())
      |                 ~~~~~~~~~^~~
/usr/include/c++/14/bits/stl_vector.h:788:7: note: candidate: 'std::vector<_Tp, _Alloc>& std::vector<_Tp, _Alloc>::operator=(std::initializer_list<_Tp>) [with _Tp = int; _Alloc = std::allocator<int>]'
  788 |       operator=(initializer_list<value_type> __l)
      |       ^~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:788:46: note:   no known conversion for argument 1 from 'std::map<int, int>::mapped_type' {aka 'int'} to 'std::initializer_list<int>'
  788 |       operator=(initializer_list<value_type> __l)
      |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
a.cc:26:7: error: request for member 'size' in 't', which is of non-class type 'int'
   26 |   b=t.size()-1;
      |       ^~~~
a.cc:28:21: error: request for member 'size' in 't', which is of non-class type 'int'
   28 |   if(k<(long long)t.size()){
      |                     ^~~~