Submission #891317

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Source Code Expand

#include <iostream>
#include <vector>
#include <cstdio>
#include <algorithm>
#include <cassert>
#include <utility>
#include <string>
#include <cmath>
#include <set>
#include <map>
using namespace std;
#define rep(i,n) for(int i = 0; i < n; ++i)
typedef long long ll;
typedef pair<int,int> pii;
int main(){
    int n;
    cin >> n;
    vector<int>a(n);
    rep(i,n){
        cin >> a[i];
        a[i]--;
    }
    int ans=0;
    rep(i,n){
        if(a[a[i]] == i ){
            ans++;
        }
    }
    cout << ans/2 << endl;
    
    return 0;
}

Submission Info

Judge Result