Submission #890206

---

Source Code Expand

#include <bits/stdc++.h>

#define sz(a) (int)(a).size()
#define pb push_back
#define all(a) (a).begin(), (a).end()

using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef long double ld;

int main()
{

    //ifstream cin("input.txt");

    int n;
    cin >> n;

    vector<int> a(n);
    for (int i = 0; i < n; ++i) {
        cin >> a[i];
        --a[i];
    }

    int ans = 0;
    for (int i = 0; i < n; ++i) {
        if (a[a[i]] == i) {
            ++ans;
        }
    }
    cout << ans / 2 << '\n';

}

Submission Info

Judge Result