C语言一个单链表L=(a1 , a2 , … , an-1 , an)，其逆单链表定义为L’=( an , an-1 , … , a2 , a1)，要求逆单链表仍占用原单链表的空间。

/*
开发者：慢蜗牛 开发时间：2020.6.11
程序功能：顺序输出和逆序输出
*/
#include<stdio.h>
#include<malloc.h>
#define LEN sizeof(struct L)
void print(struct L* head);
void _print(struct L* head);
struct L//结构体
{
    int a;
    struct L* next;
};
struct L* creat()//建立无头节点的链表
{
    struct L* head;
    struct L* p1, * p2; int n = 0;
    p1 = p2 = (struct L*)malloc(LEN);
    scanf_s("%d", &p1->a);
    head = NULL;
    while (p1->a != -1)
    {
        n = n + 1;
        if (n == 1) head = p1;
        else p2->next = p1;
        p2 = p1;
        p1 = (struct L*)malloc(LEN);
        scanf_s("%d", &p1->a);
    }
p2->next = NULL;
return(head);
}
void print(struct L* head)//顺序输出链表函数
{
    struct L* p;
    p = head;
    do
    {
        printf("--%d", p->a);
        p = p->next;
    } while (p != NULL);
}
void _print(struct L* head)//反转链表并输出
{
    struct L* p1, * p2, * p3, * p;
    p3 = p1 = p2 = (struct L*)malloc(LEN);
    p1->next = head; head = p1;
    p1 = head->next;
    do//反转
    {
        p3=head->next; p2 = p1->next;
        head->next = p2; p1->next = p2->next;
        p2->next = p3;
    } while (p1->next!=NULL);
    p = head->next;
    do//输出头节点链表
    {
        printf("--%d", p->a);
        p = p->next;
    } while (p != NULL);
}
void main()//主函数
{
    struct L* LA;
    LA = creat();//调用函数建立链表
    print(LA);//输出顺序链表
    printf("\n");
    print(LA);//输出逆序链表
}