Language: C++

#include <bits/stdc++.h>
#define REP(i,n) for(int i=0;i<n;i++)
#define REPP(i,n) for(int i=1;i<=n;i++)
const double PI = acos(-1);
const double EPS = 1e-15;
long long INF=(long long)1E17;
#define i_7 (long long)(1E9+7)
long mod(long a){
    long long c=a%i_7;
    if(c>=0)return c;
    return c+i_7;
}
using namespace std;
bool prime(int n){
  if(n==1){
    return false;
  }else if(n==2){
    return true;
  }else{
    for(int i=2;i<=sqrt(n);i++){
      if(n%i==0){
        return false;
      }
    }
    return true;
  }
}

long long gcd(long long a, long long b){
  if(a<b){
    swap(a,b);
  }
  if(a%b==0){
    return b;
  }else{
    return gcd(b,a%b);
  }
}
 
long long lcm(long long x, long long y){
  return (x/gcd(x,y))*y;
}
 
class UnionFind {
    public:
    //各頂点の親の番号を格納する。その頂点自身が親だった場合は-(その集合のサイズ)を入れる。
    vector<int> Parent;
    
    //クラスを作るときは、Parentの値を全て-1にする。
    //以下のようにすると全てバラバラの頂点として解釈できる。
    UnionFind(int N) {
        Parent = vector<int>(N, -1);
    }
    
    //Aがどのグループに属しているか調べる
    int root(int A) {
        if (Parent[A] < 0) return A;
        return Parent[A] = root(Parent[A]);
    }
    
    //自分のいるグループの頂点数を調べる
    int size(int A) {
        return -Parent[root(A)];//先祖をrootで取っておきたい。
    }
    
    //AとBをくっ付ける
    bool connect(int A, int B) {
        //AとBを直接つなぐのではなく、root(A)にroot(B)をくっつける
        A = root(A);
        B = root(B);
        if (A == B) {
            //すでにくっついてるからくっ付けない
            return false;
        }
        
        //大きい方(A)に小さいほう(B)をくっ付けたい
        //大小が逆だったらAとBをひっくり返す。
        if (size(A) < size(B)) swap(A, B);
        
        //Aのサイズを更新する
        Parent[A] += Parent[B];
        //Bの親をAに変更する
        Parent[B] = A;
        
        return true;
    }
};


  
int main(){
  
  int n;
  cin>>n;
  vector<int> a(n);
  map<int,int> mp;
  REP(i,n){
    cin>>a[i];
    map[a[i]] = i%2;
  }
  
  int ans=0;
  sort(a.begin(),a.end());
  for(int i=0;i<n;i+=2){
    if(mp[a[i]]==0)continue;
    ans++;
  }
  cout<<ans<<endl;
  return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:99:10: error: expected ']' before '[' token
   99 |     map[a[i]] = i%2;
      |          ^
      |          ]
a.cc:99:19: error: class template argument deduction failed:
   99 |     map[a[i]] = i%2;
      |                   ^
a.cc:99:19: error: no matching function for call to 'map(int)'
In file included from /usr/include/c++/14/map:63,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:152,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_map.h:1473:5: note: candidate: 'template<class _InputIterator, class _Compare, class _Allocator, class, class, class> std::map(_InputIterator, _InputIterator, _Compare, _Allocator)-> map<typename remove_const<typename iterator_traits< <template-parameter-1-1> >::value_type::first_type>::type, typename iterator_traits< <template-parameter-1-1> >::value_type::second_type, _Compare, _Allocator>'
 1473 |     map(_InputIterator, _InputIterator,
      |     ^~~
/usr/include/c++/14/bits/stl_map.h:1473:5: note:   candidate expects 2 arguments, 1 provided
/usr/include/c++/14/bits/stl_map.h:1482:5: note: candidate: 'template<class _Key, class _Tp, class _Compare, class _Allocator, class, class> std::map(initializer_list<pair<_T1, _T2> >, _Compare, _Allocator)-> map<_Key, _Tp, _Compare, _Allocator>'
 1482 |     map(initializer_list<pair<_Key, _Tp>>,
      |     ^~~
/usr/include/c++/14/bits/stl_map.h:1482:5: note:   template argument deduction/substitution failed:
a.cc:99:19: note:   mismatched types 'std::initializer_list<std::pair<_T1, _T2> >' and 'int'
   99 |     map[a[i]] = i%2;
      |                   ^
/usr/include/c++/14/bits/stl_map.h:1489:5: note: candidate: 'template<class _InputIterator, class _Allocator, class, class> std::map(_InputIterator, _InputIterator, _Allocator)-> map<typename remove_const<typename iterator_traits< <template-parameter-1-1> >::value_type::first_type>::type, typename iterator_traits< <template-parameter-1-1> >::value_type::second_type, less<typename remove_const<typename iterator_traits< <template-parameter-1-1> >::value_type::first_type>::type>, _Allocator>'
 1489 |     map(_InputIterator, _InputIterator, _Allocator)
      |     ^~~
/usr/include/c++/14/bits/stl_map.h:1489:5: note:   candidate expects 3 arguments, 1 provided
/usr/include/c++/14/bits/stl_map.h:1495:5: note: candidate: 'template<class _Key, class _Tp, class _Allocator, class> std::map(initializer_list<pair<_T1, _T2> >, _Allocator)-> map<_Key, _Tp, less<_Key>, _Allocator>'
 1495 |     map(initializer_list<pair<_Key, _Tp>>, _Allocator)
      |     ^~~
/usr/include/c++/14/bits/stl_map.h:1495:5: note:   candidate expects 2 arguments, 1 provided
/usr/include/c++/14/bits/stl_map.h:102:11: note: candidate: 'template<class _Key, class _Tp, class _Compare, class _Alloc> map(std::map<_Key, _Tp, _Compare, _Alloc>)-> std::map<_Key, _Tp, _Compare, _Alloc>'
  102 |     class map
      |           ^~~
/usr/include/c++/14/bits/stl_map.h:102:11: note:   template argument deduction/substitution failed:
a.cc:99:19: note:   mismatched types 'std::map<_Key, _Tp, _Compare, _Alloc>' and 'int'
   99 |     map[a[i]] = i%2;
      |                   ^
/usr/include/c++/14/bits/stl_map.h:197:7: note: candidate: 'template<class _Key, class _Tp, class _Compare, class _Alloc> map()-> std::map<_Key, _Tp, _Compare, _Alloc>'
  197 |       map() = default;
      |       ^~~
/usr/include/c++/14/bits/stl_map.h:197:7: note:   candidate expects 0 arguments, 1 provided
/usr/include/c++/14/bits/stl_map.h:219:7: note: candidate: 'template<class _Key, class _Tp, class _Compare, class _Alloc> map(const std::map<_Key, _Tp, _Compare, _Allocator>&)-> std::map<_Key, _Tp, _Compare, _Alloc>'
  219 |       map(const map&) = default;
      |       ^~~
/usr/include/c++/14/bits/stl_map.h:219:7: note:   template argument deduction/substitution failed:
a.cc:99:19: note:   mismatched types 'const std::map<_Key, _Tp, _Compare, _Allocator>' and 'int'
   99 |     map[a[i]] = i%2;
      |                   ^
/usr/include/c++/14/bits/stl_map.h:227:7: note: candidate: 'template<class _Key, class _Tp, class _Compare, class _Alloc> map(std::map<_Key, _Tp, _Compare, _Allocator>&&)-> std::map<_Key, _Tp, _Compare, _Alloc>'
  227 |       map(map&&) = default;
      |       ^~~
/usr/include/c++/14/bits/stl_map.h:227:7: note:   template argument deduction/substitution failed:
a.cc:99:19: note:   mismatched types 'std::map<_Key, _Tp, _Compare, _Allocator>' and 'int'
   99 |     map[a[i]] = i%2;
      |                   ^
/usr/include/c++/14/bits/stl_map.h:240:7: note: candidate: 'template<class _Key, class _Tp, class _Compare, class _Alloc> map(std::initializer_list<std::pair<const _Key, _Val> >, const _Compare&, const _Alloc&)-> std::map<_Key, _Tp, _Compare, _Alloc>'
  240 |       map(initializer_list<value_type> __l,
      |       ^~~
/usr/include/c++/14/bits/stl_map.h:240:7: note:   template argument deduction/substitution failed:
a.cc:99:19: note:   mismatched types 'std::initializer_list<std::pair<const _Key, _Val> >' and 'int'
   99 |     map[a[i]] = i%2;
      |                   ^
/usr/include/c++/14/bits/stl_map.h:252:7: note: candidate: 'template<class _Key, class _Tp, class _Compare, class _Alloc> map(const std::map<_Key, _Tp, _Compare, _Allocator>&, std::__type_identity_t<_Alloc>&)-> std::map<_Key, _Tp, _Compare, _Alloc>'
  252 |       map(const map& __m, const __type_identity_t<allocator_type>& __a)
      |       ^~~
/usr/include/c++/14/bits/stl_map.h:252:7: note:   candidate expects 2 arguments, 1 provided
/usr/include/c++/14/bits/stl_map.h:256:7: note: candidate: 'template<class _Key, class _Tp, class _Compare, class _Alloc> map(std::map<_Key, _Tp, _Compare, _Allocator>&&, std::__type_identity_t<_Alloc>&)-> std::map<_Key, _Tp, _Compare, _Alloc>'
  256 |       map(map&& __m, const __type_identity_t<allocator_type>& __a)
      |       ^~~
/usr/include/c++/14/bits/stl_map.h:256:7: note:   candidate expects 2 arguments, 1 provided
/usr/include/c++/14/bits/stl_map.h:262:7: note: candidate: 'template<class _Key, class _Tp, class _Compare, class _Alloc> map(std::initializer_list<std::pair<const _Key, _Val> >, const _Alloc&)-> std::map<_Key, _Tp, _Compare, _Alloc>'
  262 |       map(initializer_list<value_type> __l, const allocator_type& __a)
      |       ^~~
/usr/include/c++/14/bits/stl_map.h:262:7: note:   candidate expects 2 arguments, 1 provided
/usr/include/c++/14/bits/stl_map.h:268:9: note: candidate: 'template<class _Key, class _Tp, class _Compare, class _Alloc, class _InputIterator> map(_InputIterator, _InputIterator, const _Alloc&)-> std::map<_Key, _Tp, _Compare, _Alloc>'
  268 |         map(_InputIterator __first, _InputIterator __last,
      |         ^~~
/usr/include/c++/14/bits/stl_map.h:268:9: note:   candidate expects 3 arguments, 1 provided
/usr/include/c++/14/bits/stl_map.h:285:9: note: candidate: 'template<class _Key, class _Tp, class _Compare, class _Alloc, class _InputIterator> map(_InputIterator, _InputIterator)-> std::map<_Key, _Tp, _Compare, _Alloc>'
  285 |         map(_InputIterator __first, _InputIterator __last)
      |         ^~~
/usr/include/c++/14/bits/stl_map.h:285:9: note:   candidate expects 2 arguments, 1 provided
/usr/include/c++/14/bits/stl_map.h:302:9: note: candidate: 'template<class _Key, class _Tp, class _Compare, class _Alloc, class _InputIterator> map(_InputIterator, _InputIterator, const _Compare&, const _Alloc&)-> std::map<_Key, _Tp, _Compare, _Alloc>'
  302 |         map(_InputIterator __first, _InputIterator __last,
      |         ^~~
/usr/include/c++/14/bits/stl_map.h:302:9: note:   candidate expects 3 arguments, 1 provided
a.cc:99:19: note: explicit deduction guides not considered for copy-initialization
   99 |     map[a[i]] = i%2;
      |                   ^