Submission #891768

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Source Code Expand

#include<iostream>
#include<cstdio>
#include<vector>
#include<queue>
#include<map>
#include<string>
#include<algorithm>
#include<functional>
#define FOR(i,a,b) for (int i=(a);i<(b);i++)
#define RFOR(i,a,b) for (int i=(b)-1;i>=(a);i--)
#define REP(i,n) for (int i=0;i<(n);i++)
#define RREP(i,n) for (int i=(n)-1;i>=0;i--)
#define inf INT_MAX/3
#define INF INT_MAX/3
#define PB push_back
#define pb push_back
#define MP make_pair
#define mp make_pair
#define ALL(a) (a).begin(),(a).end()
#define all(a) (a).begin(),(a).end()
#define SET(a,c) memset(a,c,sizeof a)
#define CLR(a) memset(a,0,sizeof a)
#define PII pair<int,int>
#define pii pair<int,int>
#define pcc pair<char,char>
#define pic pair<int,char>
#define pci pair<char,int>
#define VS vector<string>
#define VI vector<int>
#define debug(x) cout<<#x<<": "<<x<<endl
#define DEBUG(x) cout<<#x<<": "<<x<<endl
#define MIN(a,b) (a>b?b:a)
#define MAX(a,b) (a>b?a:b)
#define pi 2*acos(0.0)
#define INFILE() freopen("in0.txt","r",stdin)
#define OUTFILE()freopen("out0.txt","w",stdout)
#define in scanf
#define out printf
#define LL long long
#define ll long long
#define ULL unsigned long long
#define ull unsigned long long
#define eps 1e-14
#define FST first
#define SEC second
using namespace std;
int a[100010];
int main(){
  int N,ans=0;
  cin>>N;
  REP(i,N)cin>>a[i];
  REP(i,N){
    if(a[a[i]]==i)ans++;
  }
  cout<<ans<<endl;
}

Submission Info

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