剑指offer：输出该链表中倒数第k个结点

题目描述

输入一个链表，输出该链表中倒数第k个结点。

struct ListNode {int val;struct ListNode *next;ListNode(int x) :val(x), next(NULL) {}};*/class Solution {public:    //快慢指针，快指针先走n-1步    ListNode* FindKthToTail(ListNode* pListHead, unsigned int k) {        if(pListHead == NULL)//代码的鲁棒性            return NULL;                if(k <= 0)//代码的鲁棒性            return NULL;                ListNode* fastp = pListHead;         ListNode* slowp = pListHead;                while(--k > 0)        {            fastp = fastp->next;            if(fastp == NULL)//代码的鲁棒性                return NULL;        }                while(fastp->next != NULL)        {            fastp = fastp->next;            slowp = slowp->next;        }        return slowp;    }};