Submission #891774

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Source Code Expand

#include<iostream>
#include<string>
#include<cstring>
#include<cstdio>
#include<cmath>
#include <utility>
#include<cstdlib>
#include<vector>
#include<set>
#include<map>
#include<queue>
#include<functional>
#include<algorithm>
#define ms0(a) memset(a,0,sizeof(a))
#define ms1(a) memset(a,-1,sizeof(a))
#define pb(a) push_back(a)
using namespace std;
typedef long long  ll;
//typedef __int64  ll;
const double Eps = (double)0.5;
const int M = 1e9 + 7;
const int N = 1e5 + 5;
const double PI = acos(-1.0);
int a[N];
bool b[N];
int main()
{
    int n;
    cin >> n;
    for(int i=1; i <= n; i++)
        cin>>a[i];
    int asr = 0;
    for(int i=1; i<= n ; i++)
    {
        if(!b[i])
        {
            int j = a[i];
            int k = a[j];
            if(i == k)
            {
                asr++;
                b[j] = true;
            }
        }
    }
    cout<<asr<<endl;
}

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