//排序
void sort(dlist_t head)
{
    dlist_t tmp = head->next,p = NULL,q = NULL;

    //將連結串列置空
    head->next = head;
    head->prev = head;

    while(tmp!=head){
        //儲存原連結串列中tmp的下一個節點
        q = tmp->next;
        
        //找到tmp插入的位置
        for(p=head->prev;p!=head&&p->data>tmp->data;p=p->prev);
        //將tmp插入到p之後
        tmp->prev = p;
        tmp->next = p->next;
        p->next->prev = tmp;
        p->next = tmp;

        //將tmp指向要插入的下一個節點
        tmp = q;
    }
    
}