9466 텀 프로젝트(hard)

#include <stdio.h>
#include <string.h>
 
int fin[100005];
int arr[100005]; 
int visit[100005];
 
int start, cnt = 0;
 
void dfs(int idx);
 
int main() {
    int t;
    scanf("%d", &t);
 
    while (t--) {
        int n;
        scanf("%d", &n);
 
        memset(fin, 0, sizeof(int) * (n + 1));
        memset(arr, 0, sizeof(int) * (n + 1));
        memset(visit, 0, sizeof(int) * (n + 1));
 
        for (int i = 1; i <= n; i++) {
            scanf("%d", &arr[i]);
        }
        
        cnt = 0;
        for (int i = 1; i <= n; i++) {
            if (visit[i] == 0) {                
                dfs(i);
            }
        }
        printf("%d\n", n-cnt);
    }
}
 
void dfs(int idx) {
    if (visit[idx] == 0) {        
        visit[idx] = 1;
        dfs(arr[idx]);
    }
    else if (visit[idx] == 1 && fin[idx] == 0) {        
        for (int i = arr[idx]; i != idx; i = arr[i]) {        
            cnt++;
        }        
        cnt++;        
    }
    fin[idx] = 1;
}