逆转一个链表

在一个list中，我们先让头结点的next域指向结点2，再让结点1的next域指向结点3，最后将结点2的next域指向结点1，
就完成了第一次交换，顺序就变成了Header-结点2-结点1-结点3-结点4-NULL

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

void reverse_list(list *head)
{
    list *prev = head, *cur = head->next, *next = NULL;

    if (NULL == head || NULL == head->next)
    {
        return ;
    }
    
    while (cur)
    {
        next = cur->next;
        cur->next = prev;
        prev = cur;
        cur = next;
    }

    head->next = NULL;
    head = prev;
}