Submission #890845

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;
#define sz(x) ((int) (x).size())
#define forn(i,n) for (int i = 0; i < int(n); ++i)
typedef long long ll;
typedef long long i64;
typedef long double ld;
const int inf = int(1e9) + int(1e5);
const ll infl = ll(2e18) + ll(1e10);

int a[100100];

int main() {
    #ifdef LOCAL
    assert(freopen("b.in", "r", stdin));
    #else
    #endif
    int n;
    cin >> n;
    forn (i, n) {
        cin >> a[i];
        --a[i];
    }
    int res = 0;
    forn (i, n) {
        int x = a[a[i]];
        if (x == i)
            ++res;
    }
    cout << res / 2 << '\n';
}

Submission Info

Judge Result