Submission #1587541

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Source Code Expand

#include<bits/stdc++.h>

using namespace std;
using ll = long long;
using ld = long double;
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define reps(i,s,n) for(int i=(int)(s);i<(int)(n);i++)
const ll mod = 1e9 + 7;
const int INF = 1e9;

int main() {
	cin.sync_with_stdio(false);
	int N;
	cin >> N;
	vector<int>a(N);
	rep(i, N) {
		cin >> a[i];
		a[i]--;
	}
	int ans = 0;
	rep(i, N) {
		if (a[a[i]] == i)ans++;
	}
	cout << ans / 2 << endl;
	return 0;
}

Submission Info

Judge Result