Submission #1611650

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Source Code Expand

#include "bits/stdc++.h"

using namespace std;
using ll = long long;

const int dx[4] = { 1,0,-1,0 };
const int dy[4] = { 0,1,0,-1 };

#define INF 99999999
#define MOD (int)1e9 + 7
#define rep(i,n) for(int i = 0;i<n;i++)

int main() {

	int n;
	int a[100000];
	int cnt = 0;

	cin >> n;

	rep(i, n) {
		cin >> a[i];
		a[i]--;
	}

	rep(i, n) {
		if (a[a[i]]  == i ) {
			cnt++;
			a[a[i]] = -1;
			a[i] = -1;
		}
	}

	cout << cnt << endl;

	return 0;
}

Submission Info

Judge Result