给定程序中，函数fun的功能是将带头结点的单向链表逆置，即若原链表中从头至尾结点数据与依次为2、4、6、8、10，逆置后，从头至尾结点数据依次为10、8、6、4、2。 
请在程序的下画线处填入正确的内容并将下画线删除，使程序得出正确的结果。 
试题程序。

 1 #define N 5
 2 typedef struct node
 3 {
 4     int data;
 5     struct node *next;
 6 } NODE;
 7 void fun(NODE *h)
 8 {
 9     NODE *p, *q, *r;
10
11     p = h-> 1 ;
12     if (p == 2 )
13         return;
14     q = p->next;
15     p->next = NULL;
16     while (q)
17     {
18         r = q->next; q->next = p;
19         p = q; q = 3 );
20     }
21     h->next = p;
22 }
23 NODE *creatlist(int a[ ])
24 {
25     NODE *h, *p, *q; int i;
26     h = (NODE *)malloc(sizeof(NODE));
27     h->next = NULL;
28     for (i = 0; i < N; i++)
29     {
30         q = (NODE *)malloc(sizeof(NODE));
31         q->data = a[i];
32         p->next = q;
33         p = q;
34     }
35
36 }
37  return h;
38 }
39 void outlist(NODE *h)
40 {
41     NODE *p;
42     p = h->next;
43     if (p == NULL)
44         printf("The list is NULL!\n");
45     else
46     {
47         printf("\nHead ");
48         do
49         {
50             printf("->%d", p->data);
51             p = p->next;
52         }
53         while (p != NULL);
54         printf("->End\n");
55
56     }
57
58 }
59 main( )
60 {
61     NODE *head;
62     int a[N] = {2, 4, 6, 8, 10};
63     head = creatlist(a);
64     printf("\nThe original list:\n");
65     outlist(head);
66     fun(head);
67     printf("\nThe list after inverting :\n");
68     outlist(head);
69 }

答案：

你的答案 (正确)

1  next

2  NULL

3  r