Leetcode刷题记录——面试题 02.02. 返回倒数第 k 个节点

设置两个指针
start和res
start先出发，走k-1次
此后，start和res一起后移 直至start为队尾 res即为所求

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None

class Solution:
    def kthToLast(self, head: ListNode, k: int) -> int:
        start = head
        res = head
        for i in range(k-1):
            start = start.next
        while start.next is not None:
            start = start.next
            res = res.next
        return res.val