[数据结构与算法]将带头节点单链表元素逆置 C语言

函数fun的功能是将带头结点的单向链表逆置。

若原链表中从头至尾结点数据域依次为：2、4、6、8、10

逆置后，从头至尾结点数据域依饮为：10、8、6、4、2

#include <stdio.h>
#include <stdlib.h>
#define N 5
typedef struct node
{
   int data;
   struct node *next;
} NODE;
void fun(NODE *h) {
   NODE *p, *q, *r;
   p = h->next;
   if (p == NULL)
      return;
   q = p->next;
   p->next = NULL;
   while (q) {
      r = q->next;
      q->next = p;
      p = q;
      q = r;
   }
   h->next = p;
}
NODE *creatlist(int a[]) {
   NODE *h, *p, *q;
   int i;
   h = (NODE *)malloc(sizeof(NODE));
   h->next = NULL;
   for (i = 0; i < N; i++) {
      q = (NODE *)malloc(sizeof(NODE));
      q->data = a[i];
      q->next = NULL;
      if (h->next == NULL)
         h->next = p = q;
      else
      {
         p->next = q;
         p = q;
      }
   }
   return h;
}
void outlist(NODE *h){
   NODE *p;
   p = h->next;
   if (p == NULL)
      printf("The list is NULL!\n");
   else {
      printf("\tHead");
      do {
         printf("->%d", p->data);
         p = p->next;
      } while (p != NULL);
      printf("->End\n");
   }
}
int main(){
   NODE *head;
   int a[N] = {2, 4, 6, 8, 10};
   head = creatlist(a);
   printf("The original list:\n");
   outlist(head);
   fun(head);
   printf("The list after inverting:\n");
   outlist(head);
}

?程序结果：