class Solution {
public:
    ListNode* findKthToTail(ListNode* pListHead, int k) {
        ListNode*res,*scan;
        res=scan=pListHead;
        for(int i=0;i<k;i++){
            if(scan==NULL)return NULL;
            scan=scan->next;
        }
        while(scan){
            res=res->next;
            scan=scan->next;
        }
        return res;
    }
};