单链表逆转算法

void rev(linknode **phead)
{
    linknode *p1, *p2, *p3;
    p1 = p2 = p3;
    if ((*phead == NULL) || (*phead)->pNext == NULL)
    {
        return;
    }
    else
    {
        p1 = *phead;
        p2 = p1->pNext;
        while (p2 != NULL)
        {
            p3 = p2->pNext;
            p2->pNext = p1; //让本应该指向前方的pNext指针向反方向指去.也是实现逆转最关键的一步.
            p1 = p2;        //把p1移动到p2的位置,{p1指针指向p2的节点}
            p2 = p3;        //把p2移动到p3的位置,{p2指针指向p3的节点}
        }
        (*phead)->pNext = NULL;
        (*phead) = p1;
    }

}