#include <bits/stdc++.h>
using namespace std;
#define X first
#define Y second
int state[100005]={0};
int num[100005]={0};
const int IN=-1;
const int not_vis=0;
void run(int x) {
int cur=x;
while(1) {
//시작 숫자로 표시
state[cur]=x;
//다음 숫자로 넘어감
cur=num[cur];
//싸이클임
if(state[cur]==x) {
while(state[cur] != IN) {
state[cur]=IN;
cur=num[cur];
}
return;
//이전에 방문함
} else if(state[cur]!= not_vis) return;
}
}
int main() {
cin.tie(0);
int t;
cin >> t;
while(t--) {
int n;
cin >> n;
fill(state+1,state+n+1,0);
for(int i=1; i<=n; i++) {
cin >> num[i];
}
for(int i=0; i<=n; i++) {
if(state[i]==not_vis) run(i);
}
int cnt=0;
for(int i=1; i<=n; i++) {
if(state[i]!=In) cnt++;
}
cout << cnt <<'\n';
}
return 0;
}
To embed this project on your website, copy the following code and paste it into your website's HTML: