Submission #3784650

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Source Code Expand

#include <cstdio>
#include <vector>
#include <algorithm>
#include <iostream>
#include <cstring>
using namespace std ;

typedef long long ll ;
#define rep (i , n ) for ( int i =0; i < n ; i++)
#define _sort(arg) sort(begin(arg), end(arg))
#define MOD 1000000007
#define pb push_back
#define DEBUG(x) cout << #x << ": " << x << endl;

/*
__attribute__((constructor))
void initial()
{
	cin.tie(NULL);
	ios::sync_with_stdio(false);
}
*/

int main()
{
	cin.tie(NULL);
	ios::sync_with_stdio(false);

	int N;
	cin >> N;
	int a[N+1];
	a[0] = 0;
	for (int i = 1; i <= N; i++)
	{
		cin >> a[i];
	}

	int count = 0;
	for (int i = 1; i <= N; i++)
	{
		//cout << "i=" << i << "; a[i]=" << a[i] << "; a[a[i]]=" << a[a[i]] << endl;
		if (i > a[i])
		{
			continue;
		}

		if (i == a[a[i]])
		{
			count++;
		}
	}
	
	cout << count << endl;
	return 0;
}

Submission Info

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