Freshman's Database

#include <bits/stdc++.h>

#define _ ios_base::sync_with_stdio(0);cin.tie();
#define ll long long
#define vi vector<int>
#define pb push_back
#define pii pair<int, int>
#define vpii vector<pii>

using namespace std;

int isancestor(int* dp, int* o, int i, vi v) {
    //cout << "isancestor " << i << endl;
    if(find(v.begin(), v.end(), i) != v.end()) {
        return true;
    }
    if(dp[i-1] == 1) {
        return false;
    }
    v.push_back(i);
    dp[i-1] = 1;
    return isancestor(dp, o, o[i-1], v);
}

int main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0);

    int n;
    cin >> n;
    int o[n];
    int dp[n];
    int c = 0;

    for(int i=0;i<n;i++) {
        dp[i] = 0;
        cin >> o[i];
    }
    
    for(int i=0;i<n;i++) {
        if(isancestor(dp, o, i+1, vi())) {
            c++;
        }
    }

    cout << c << "\n";

	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