Submission #891800

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Source Code Expand

#include <iostream>
#include <vector>
#include <algorithm>
#include <set>
#include <cstring>
#include <string>
#include <stack>
#include <tuple>

using namespace std;
typedef long long ll;
ll MOD = 1e9 + 7;

int main()
{
    int n;
    cin >> n;
    vector<int> a(n);
    for (int i = 0; i < n; i++)
    {
        int in;
        cin >> in;
        a[i] = in - 1;
    }
    int ans = 0;
    for (int i = 0; i < n; i++) if (a[a[i]] == i) ans++;
    cout << ans/2 << endl;
    return 0;
}

Submission Info

Judge Result