数据结构链表中删除重复元素，为什么运行出错呢？帮我看看吧 谢谢
程序代码：例如链表为1,2，2,1
输出为1,2
#include <stdio.h>
#include <malloc.h>
struct list{
int data;
struct list *next;
};
struct list *create(){
int n;
struct list *head,*p,*q;
head=(struct list *)malloc(sizeof(struct list));
head->next=NULL;
q=head;
printf("输入链表（0为结束）:\n");
scanf("%d",&n);
while(n<=0){
printf("值不正确\n");
scanf("%d",&n);
}
while(n>0){
p=(struct list *)malloc(sizeof(struct list));
p->data=n;
p->next=NULL;
q->next=p;
q=p;
printf("下一个");
scanf("%d",&n);
}
return head;
}
void shan(struct list *head){//删除链表中相等的元素
struct list *p,*q,*s;
q=head->next;
while(q->next){//printf("a");
p=q->next;
s=q;
while(p){//printf("b");
if(q->data==p->data){
s->next=p->next;
free(p);
p=s->next;//printf("c");
}else{printf("d");
p=p->next;
s=s->next;
}
}//printf("e");
q=q->next;//printf("f");
}//printf("d");
}
void print(struct list *head){
while(head->next){
printf("%3d",head->next->data);
head=head->next;
}
}
void main(){
struct list *head,*p,*q;
head=create();
print(head);
printf("\n");
// zhuanzhi1(head);
shan(head);
print(head);
}
