1 /*
 2 struct ListNode {
 3     int val;
 4     struct ListNode *next;
 5     ListNode(int x) :
 6             val(x), next(NULL) {
 7     }
 8 };*/
 9 class Solution {
10 public:
11     ListNode* FindKthToTail(ListNode* pListHead, unsigned int k) {
12         if(!pListHead || k<=0) return nullptr;
13         ListNode* fast = pListHead;
14         ListNode* slow = pListHead;
15         for(int i=0;i<k-1;i++){
16             fast = fast->next;
17             if(!fast) return nullptr;
18         }
19         while(fast->next){
20             fast = fast->next;
21             slow = slow->next;
22         }
23         return slow;
24     }
25 };

 1 # -*- coding:utf-8 -*-
 2 # class ListNode:
 3 #     def __init__(self, x):
 4 #         self.val = x
 5 #         self.next = None
 6 
 7 class Solution:
 8     def FindKthToTail(self, head, k):
 9         # write code here
10         res = []
11         while head:
12             res.append(head)
13             head = head.next
14         if k<1 or k>len(res):
15             return
16         return res[-k]