Submission #891102

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Source Code Expand

#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <utility>
#include <map>
#include <set>
#include <sstream>
#include <cstdio>
#include <cmath>
#include <cstdlib>
using namespace std;

#define fi first
#define se second
#define all(x) (x).begin(), (x).end()
#define rep(i,n) for(int i = 0; i < n; ++i)
#define rrep(i,n) for(int i = (int)n - 1; i >= 0; --i)

typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

int main() {
	int N;
	vector<int> a;
	cin >> N;
	a.resize(N);
	rep(i,N) cin >> a[i];

	int res = 0;
	rep(i,N) {
		if(a[a[i]-1] == i+1)
			res++;
	}
	cout << res/2 << endl;
}

Submission Info

Judge Result