Submission #890878

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Source Code Expand

// assuming you live in an expensive city, anyway!  but if you live in a really cheap area of the planet then you may find it hard to relate to the talking dinosaurs in this code strip today
#include <iostream>
#include <vector>
#include <cmath>
#include <algorithm>
#include <string>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <cstring>
#include <cassert>
using namespace std;
#define rep(i,a,n) for (int i=a;i<(n);i++)
#define per(i,a,n) for (int i=(n)-1;i>=(a);i--)
typedef long long ll;


int main() {
    ios_base::sync_with_stdio(false);
    int n;
    cin >> n;
    vector<int> a(n);
    rep(i, 0, n) cin >> a[i], a[i]--;
    int res = 0;
    rep(i, 0, n) if (a[a[i]] == i) res++;
    cout << (res / 2) << endl;
    return 0;
}

Submission Info

Judge Result