python剑指offer 链表倒数第k个结点

# -*- coding:utf-8 -*-
# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None
class Solution:
def FindKthToTail(self, head, k):
first = head
#         sencond = head
length = 0
if k == 0:
return
while first :
first = first.next
length += 1
if length == k:
sencond = head
elif length > k:
sencond = sencond.next

if length < k:
return
return sencond