【救命啊 80pts】指针循环链表

#include <bits/stdc++.h>
#define int long long
using namespace std;
struct List{
    int data;
    List *prev = NULL, *next = NULL;
}*head, *tail;
vector<List*> students;
inline int read(){
    int x=0,f=1;
    char ch=getchar();
    while(ch<'0'||ch>'9'){
        if(ch=='-')
            f=-1;
        ch=getchar();
    }
    while(ch>='0' && ch<='9')
        x=x*10+ch-'0',ch=getchar();
    return x*f;
}
void write(int x){
    if(x<0)
        putchar('-'),x=-x;
    if(x>9)
        write(x/10);
    putchar(x%10+'0');
    return;
}
signed main(){
    int n = read(), m;
    students.resize(n + 10);
    head = new List;
    head->data = 1, students[1] = head;
    tail = head, head->prev = tail;
    for(int i = 2, k, p; i <= n; i++){
        k = read(), p = read();
        List *target = students[k], *now = new List;
        now->data = i;
        if(p == 0){
            if(target == head){
                now->prev = tail, now->next = head;
                head->prev = now, head = now;
                goto end;
            }
            List* tmp = target->prev;
            now->next = target, now->prev = tmp;
            tmp->next = now, target->prev = now;
        }else{
            if(target->next == NULL) target->next = now;
            List* tmp = target->next;
            now->prev = target, now->next = tmp;
            tmp->prev = now, target->next = now;
            if(target == tail) tail = now, head->prev = tail;
        }
end:    students[i] = now, tail->next = head;
    }
    m = read();
    for(int i = 1, x; i <= m; i++){
        x = read();
        students[x]->data = 0;
    }
    List *it;
    for(it = head; it->next != head; it = it->next){
        if(it->data == 0) continue;
        write(it->data); putchar(' ');
        //printf("{address = 0x%x, data = %d, prev = 0x%x, next = 0x%x}\n", it, it->data, it->prev, it->next);
    }
    if(it->data == 0) return 0;
    write(it->data);
    return 0;
}