c291. APCS 2017-0304-2小群體 -- 2017年3月APCS | From: [122.118.32.104] | 發表日期 : 2023-05-21 18:14

#include <iostream>

using namespace std;

 

int group(int* data, bool* used, int current)

{

if (used[current] == true) return 0;

else

{

used[current] = true;

group(data, used, data[current]);

}

}

 

int main()

{

int n;

cin >> n;

int firend[50001] = { 0 };

for (int i = 0; i < n; i++)

{

cin >> firend[i];

}

bool *used = new bool[n] { false };

int ans = 0;

for (int i = 0; i < n; i++)

{

if(used[i] == false)

{

group(firend, used, i);

ans++;

}

}

cout << ans;

}