为什么全是RE啊 上代码：

#include<stdio.h>
#include<malloc.h>
#define len sizeof(struct node)
int n,m,i=0;
struct node{
    int id;
    struct node *next;
};
struct node *creat(void){
    struct node *head,*p,*q;
    scanf("%d%d",&n,&m);
    head=(struct node*)malloc(len);
    head->next=NULL;
    p=head;
    while(n-->0){
        q=(struct node*)malloc(len);
        scanf("%d",&q->id);
        q->next=p->next;
        p->next=q;
        p=q;
    }
    p->next=NULL;
    return head;
}
void research(struct node *head){
    struct node *pt;
    int target;
    head=creat();
    pt=head;
    for( ;m>=1;m--){
        scanf("%d",&target);
        while(i!=target){
            i++;
            pt=pt->next;
        }
        printf("%d\n",pt->id);
    }
}
int main(){
    struct node *head;
    research(head);
    return 0;
}