Submission #891417

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Source Code Expand

#include <iostream>
#include <algorithm>
#include <vector>
#include <deque>
#include <queue>
#include <list>
#include <stack>
#include <string>
#include <functional>
#include <numeric>
#include <cmath>
#include <iomanip>
#include <map>
#include <set>
#include <cstdlib>
#define INF 100000000
#define _INF -100000000
#define INFLL (long long)1e14
#define _INFLL (long long)-1e14
#define Loop(i, n) for(int i = 0; i < (int)n; i++)
#define Loop1(i, n) for(int i = 1; i <= (int)n; i++)
#define Loopr(i, n) for(int i = (int)n - 1; i >= 0; i--)
#define Loopr1(i, n) for(int i = (int)n; i >= 1; i--)
using namespace std;
typedef long long int ll;
typedef vector<int> vi;
typedef vector<vector<int>> vvi;
typedef vector<ll> vll;
typedef vector<vector<ll>> vvll;
typedef pair<ll, ll> P;

static const int N = 1e5 + 5;
vi a(N);
int n;

int main() {
	cin >> n;
	Loop1(i, n) {
		cin >> a[i];
	}
	int ans = 0;
	Loop(i, n) {
		if (a[a[i]] == i) ans++;
	}
	ans /= 2;
	cout << ans << endl;
	return 0;
}

Submission Info

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