链表中倒数第K个节点

listNode *FindNtoTail(listNode *head,unsigned int n){    if(head == NULL || n == 0)         return NULL;    listNode *pHead = head;    listNode *pBehind = NULL;    unsigned int i;    // pHead 向前移动 n-1     for(i = 0;i<n-1;i++)    {        if(pHead->next != NULL)            pHead = pHead->next;        else            return NULL;    }    pBehind = head;    //同时移动，直到前一个指针到最后     while(pHead->next != NULL)    {        pHead = pHead->next;        pBehind = pBehind->next;    }    return pBehind;}