Submission #891313

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;

#define forn(i,n) for(int i=0;i<(int)(n);i++)
#define si(c) ((int)(c).size())
#define forsn(i,s,n) for(int i = (int)(s); i<((int)n); i++)
#define dforsn(i,s,n) for(int i = (int)(n)-1; i>=((int)s); i--)
#define all(c) (c).begin(), (c).end()
#define D(a) cerr << #a << "=" << a << endl;
#define pb push_back
#define eb emplace_back
#define mp make_pair

typedef long long int ll;
typedef vector<int> vi;
typedef pair<int,int> pii;

const int N = 1e5 + 10;

int n, a[N];

int main() {
    ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);

    cin >> n; forn(i,n) cin >> a[i], a[i]--;
    int res =0;
    forn(i,n) {
        if (a[a[i]] == i) res++;
    }
    cout << res/2 << endl;



    return 0;
}

Submission Info

Judge Result