链表反转

/***
reverse.c
***/
#include<stdio.h>
#include<stdlib.h>

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

struct list *create_list()
{
    return calloc(sizeof(struct list),1);
}

struct list *insert_list(struct list *ls,int n,int data)
{
    struct list *p = ls;
    while(p && n--)
    {
        p = p->next;
    }
    if(NULL == p)
    {
        return NULL;
    }
    struct list *node = create_list();
    node->data = data;
    node->next = p->next;
    p->next = node;
    return node;
}

void traverse(struct list *ls)
{
    struct list *p = ls;
    while(p)
    {
        printf("%d\n",p->data);
        p = p->next;
    }
}

void reverse(struct list *ls)
{
    if(ls->next == NULL)
    {
        return;
    }

    if(ls->next->next == NULL)
    {
        return;
    }

    struct list *last = ls->next;

    struct list *pre = ls;
    struct list *cur = ls;
    struct list *next = NULL;

    while(cur)
    {
        next = cur->next;
        cur->next = pre;
        pre = cur;
        cur = next;
    }
    
    ls->next = pre;
    last->next = NULL;

}

int main()
{
    struct list *first = create_list();
    int i;
    for(i = 0; i < 10; i++)
    {
        insert_list(first,0,i);
    }
    traverse(first);
    reverse(first);
    printf("reverse\n");
    traverse(first);
    return 0;    
}

运行结果：

ubuntu1604@ubuntu:~/wangqinghe/C/20190730$ gcc reverse.c -o reverse

ubuntu1604@ubuntu:~/wangqinghe/C/20190730$ ./reverse

0

9

8

7

6

5

4

3

2

1

0

reverse

0

0

1

2

3

4

5

6

7

8

9

 

问题：创建链表时多了一个0，存疑