Freshman's Database

using namespace std;
#include <bits/stdc++.h>

#define sz(x) ((int)x.size())
#define sqr(x) ((x)*(x))
#define pb push_back
#define clr clear()
#define inf (1<<30)
#define eps 1e-9
typedef long long i64;
typedef unsigned long long ui64;
#include <math.h>

vector<bool> visited;
vector<bool> is_cycle;
vector<int> adj;

int cycles = 0;
int start = 0;

void dfs(int node){

    if(is_cycle[node]){ return; }

    if(visited[node]){
        if(node == start){
            cycles++;
            is_cycle[node] = true;
            is_cycle[start] = true;
        }
        return;
    }

    visited[node] = true;
    dfs(adj[node]);
    visited[node] = false;
}

int main() {
    ios_base::sync_with_stdio(0);

    int n;
    cin >> n;
    for(int i = 0 ; i < n; i++){
        int temp;
        cin >> temp;
        adj.pb(temp - 1);
        visited.pb(false);
        is_cycle.pb(false);
    }

    for(int i = 0; i < n ; i++){
        if(!is_cycle[i]){
            start = i;
            dfs(i);
        }
    }

    cout << cycles << endl;

    return 0;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: TIME LIMIT EXCEEDED

Test 6

Verdict: TIME LIMIT EXCEEDED

Test 7

Verdict: TIME LIMIT EXCEEDED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: TIME LIMIT EXCEEDED