Submission #1420290

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Source Code Expand

#include "bits/stdc++.h"

using namespace std;

typedef long long ll;
typedef pair<int, int> P;
typedef vector<int> VI;
typedef vector<VI> VVI;
const double PI = 3.14159265358979323846;
const double EPS = 1e-12;
const int INF = numeric_limits<int>::max() / 2;
const int NEG_INF = numeric_limits<int>::min() / 2;
const int MOD = 1e9 + 7;

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

	int n; cin >> n;
	vector<int> v(n);
	for (int i = 0; i < n; i++) {
		cin >> v[i];
		v[i]--;
	}
	int res = 0;
	for (int i = 0; i < n; i++) {
		int love = v[i];
		if (v[love] == i) res++;
	}
	cout << res / 2 << endl;
}

Submission Info

Judge Result