/*struct ListNode {    int val;    struct ListNode *next;    ListNode(int x) :            val(x), next(NULL) {    }};*/class Solution {public:    ListNode* FindKthToTail(ListNode* pListHead, unsigned int k) {        if(pListHead == NULL || k == 0){            return NULL;        }        ListNode *pAhead = pListHead;        ListNode *pBehind = pListHead;        for(unsigned int i = 0; i < k - 1; i++){            if(pAhead->next != NULL){                pAhead = pAhead->next;            }            else{                return NULL;            }        }        while(pAhead->next != NULL){            pAhead = pAhead->next;            pBehind = pBehind->next;        }        return pBehind;    }};