链表中倒数第k个结点

经过启发的代码：

class Solution {
public:
    ListNode* FindKthToTail(ListNode* pListHead, unsigned int k) {
        if (pListHead==NULL) return pListHead;
        if(k==0) return NULL;
        ListNode* p1 = pListHead;
        ListNode* p2 = pListHead;
        unsigned int n = 1;
        while(p2->next !=NULL)
        {
            if(n < k)
            {
                n++;
            }
            else if(n == k)
            {
                p1 = p1->next;
            }
            p2 = p2->next;
        }
        if(n < k)
            return NULL;
        return p1;
    }
};