題目：
輸入一個鏈表，輸出該鏈表中倒數第k個節點。為了符合大多數人的習慣，本題從1開始計數，即鏈表的尾節點是倒數第1個節點。
例如，一個鏈表有 6 個節點，從頭節點開始，它們的值依次是 1、2、3、4、5、6。這個鏈表的倒數第 3 個節點是值為 4 的節點。
示例：
給定一個鏈表: 1->2->3->4->5, 和 k = 2.
返回鏈表 4->5.
code：
# Definition for singly-linked list.
# class ListNode:
# def __init__(self, x):
# self.val = x
# self.next = None
class Solution:
def getKthFromEnd(self, head: ListNode, k: int) -> ListNode:
temp = head
n = 0
while temp:
n+=1
temp = temp.next
for _ in range(n-k):
head = head.next
return head
# Definition for singly-linked list.
# class ListNode:
# def __init__(self, x):
# self.val = x
# self.next = None
class Solution:
def getKthFromEnd(self, head: ListNode, k: int) -> ListNode:
fast, slow = head, head
for _ in range(k-1):
fast = fast.next
while fast.next != None:
fast = fast.next
slow = slow.next
return slow
