[编程题]链表中倒数第k个结点

public class Solution {
    public ListNode FindKthToTail(ListNode head, int k) {
        ListNode res = head;
        int index = 0;
        while(head != null){
            if(index == k){
                res = res.next;
            }
            else{
                index++;
            }
            head = head.next;
        }
        if(index < k)
            return null;
        return res;
    }
}