Submission #891042

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Source Code Expand

#include <algorithm>
#include <cstdio>
#include <cstdlib>
#include <cctype>
#include <cmath>
#include <iostream>
#include <queue>
#include <list>
#include <stack>
#include <map>
#include <numeric>
#include <set>
#include <sstream>
#include <string>
#include <vector>
using namespace std;
#define REP(i,a,n) for(int i=(a); i<(int)(n); i++)
#define rep(i,n) REP(i,0,n)
#define FOR(it,c) for(__typeof((c).begin()) it=(c).begin(); it!=(c).end(); ++it)
#define ALLOF(c) (c).begin(), (c).end()
typedef long long ll;

int main(){
  ios::sync_with_stdio(false);
  int N;
  cin >> N;
  vector<int> A;
  rep(i,N){
    int a;
    cin >> a;
    a--;
    A.push_back(a);
  }

  int ret = 0;
  rep(i,A.size()){
    if(A[A[i]] == i){
      ret++;
      A[A[i]] = -1;
    }
  }
  cout << ret << endl;
  return 0;
}

Submission Info

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