Submission #891140

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Source Code Expand

#include <iostream>
#include <sstream>
#include <vector>
#include <string>
#include <cstring>
#include <algorithm>
#include <queue>
#include <map>
#include <set>

#define REP(i,k,n) for(int i=k;i<n;i++)
#define rep(i,n) for(int i=0;i<n;i++)
#define each(it,v) for(__typeof((v).begin()) it=(v).begin();it!=(v).end();it++)
#define INF 1<<30
#define mp make_pair

using namespace std;
typedef long long ll;
typedef pair<int,int> P;

int main() {
	int n;
	cin >> n;

	vector<int> v(n);
	rep(i, n) cin >> v[i];

	int ans = 0;
	rep(i, n) {
		int j = v[i];
		j--;
		int k = v[j];

		if(k == i+1) ans++;
	}

	cout << ans / 2 << endl;

	return 0;
}

Submission Info

Judge Result