Submission #891130

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Source Code Expand

#include <cstdio>
#include <iostream>
#include <cmath>
#include <cstring> 
#include <sstream>
#include <algorithm>
#include <cstdlib>
#include <map>
#include <queue>
#include <utility>
#include <vector>
#include <set>
#include <memory.h>
#include <iomanip>
#include <bitset>
#include <list>
#include <stack>
 
using namespace std;

int main()
{
    int n;
    cin >> n;
    int a[100001];
    for(int i = 1; i <= n; i++){
        cin >> a[i];
    }
    vector<bool> ischecked(n + 1, false);
    int ans = 0;
    for(int i = 1; i <= n; i++){
        if(ischecked[i]) continue;
        ischecked[i] = true;
        if(i == a[a[i]]){
            ischecked[a[i]] = true;
            ans++;
        }
    }
    cout << ans << endl;
    return 0;
}

Submission Info

Judge Result