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
}