Submission #3770515

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;
#define REP(i, n) for(int i = 0; i < n; i++)
#define REPR(i, n) for(int i = n - 1; i >= 0; i--)
#define FOR(i, m, n) for(int i = m; i < n; i++)
#define FORR(i, m, n) for(int i = m; i >= n; i--)
#define SORT(v, n) sort(v, v+n);
#define VSORT(v) sort(v.begin(), v.end());
#define ll long long
#define pb(a) push_back(a)

ll mod = 1e9 + 7;

int main(){
  cin.tie(0);
  ios::sync_with_stdio(false);

  ll n;
  cin >> n;
  ll a[n];
  map<ll, ll> mp;
  REP(i, n){
    cin >> a[i];
    mp[i + 1] = a[i];
  }

  ll ans = 0;

  REP(i, n){
    if(mp[a[i]] == i + 1) ans++;
  }

  cout << ans / 2 << endl;

  return 0;
}

Submission Info

Judge Result