哪里有问题？错误原因显示运行超时，

Question

struct ListNode *reverse( struct ListNode *head )
{
if(head==NULL||head->next==NULL)//链表为空
return head;
struct ListNode *p,*q;
p=head->next;
head->next==NULL;
while(p!=NULL)
{
q=p;
p=p->next;
q->next=head->next;
head->next=q;
}
return head;
}

这是题中的代码
#include <stdio.h>
#include <stdlib.h>

struct ListNode {
int data;
struct ListNode *next;
};

struct ListNode *createlist(); /裁判实现，细节不表/
struct ListNode *reverse( struct ListNode *head );
void printlist( struct ListNode *head )
{
struct ListNode *p = head;
while (p) {
printf("%d ", p->data);
p = p->next;
}
printf("\n");
}

int main()
{
struct ListNode *head;

head = createlist();
head = reverse(head);
printlist(head);

return 0;

}

/* 你的代码将被嵌在这里 */

Answer 1

代码修改如下，供参考：

#include <stdio.h>
#include <stdlib.h>
struct ListNode {
    int data;
    struct ListNode *next;
};

struct ListNode *createlist(); /*裁判实现，细节不表 */
struct ListNode *reverse(struct ListNode *head );
void   printlist( struct ListNode *head )
{
    struct ListNode *p = head;
    while (p) {
          printf("%d ", p->data);
          p = p->next;
    }
    printf("\n");
}

int main()
{
    struct ListNode *head;

    head = createlist();
    head = reverse(head);
    printlist(head);

    return 0;
}

/* 你的代码将被嵌在这里 */

struct ListNode *reverse( struct ListNode *head )
{
    if(head==NULL)  return head;
    struct ListNode *p,*q;
    p = head;    //p = head->next;
    head = NULL; //head->next==NULL;
    while(p!=NULL)
    {
        q = p;
        p = p->next;
        q->next=head;//q->next=head->next;
        head = q;    //head->next=q;
    }
    return head;
}