Freshman's Database

#include <iostream>

using namespace std;


int main() {
    int n;
    cin >> n;

    // Cycles
    int c = 0;
    
    std::ios::sync_with_stdio(true);

    int *p = new int[n]; // Parents
    int *v = new int[n]; // Visited
    int *w = new int[n]; // Visited
    for (int i = 0; i < n; i++) {
        cin >> p[i];
        p[i] -= 1;
        v[i] = 0;
        w[i] = -1;
    }

    for(int i = 0; i <  n; i++) {
        if (v[i]) continue; // SKIP VISITED
        v[i] = 1; // Mark as visited
        w[i] = i;
        int j = p[i];

        while(v[j] == 0) { // If we go back to beginning, 
            w[j] = i;
            v[j] = 1;
            j = p[j];
        }

        if (w[j] == i) {
            //std::cout << "f" << i << " " << j << endl;
            c++;
        }
    }

    cout << c << endl;
    
    return 0;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED