Submission #891410

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Source Code Expand

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

#define AS(arr)  (sizeof(arr)/sizeof(arr[0]))
#define ALL(c) (c).begin(),(c).end() 
#define SIZE(a) int((a).size())
#define EACH(it,c) for(__typeof((c).begin()) it=(c).begin();it!=(c).end();++it)
#define REP(i,n) for(int i=0;i<(int)n;++i)

#define DEBUG(x) cout<<#x<<": "<<x<<endl
#define DEBUG_VEC(v) cout<<#v<<":";REP(i,v.size())cout<<" "<<v[i];cout<<endl

#define pb push_back
#define mp make_pair

typedef vector<int> VI;
typedef vector<string> VS;
typedef long long LL;

const double EPS = 1e-11;
#define EQ(a,b) (abs(a-b)<EPS)
#define EQ0(x) (abs(x)<EPS)

int a[100005];
int main(void){
   int N;
   cin >> N;
   REP(i, N)
   {
       cin >> a[i];
   }
   int ret = 0;
   REP(i, N)
   {
       if(a[a[i]] == i)
       {
           ret++;
       }
   }
   cout << ret << endl;
   
}

Submission Info

Judge Result