22_KthNodeFromEnd.py

# -*- coding: utf-8 -*-
# @File    : 22_KthNodeFromEnd.py
# @Date    : 2020-10-31
# @Author  : tc
"""
剑指 Offer 22.链表中倒数第k个节点
输入一个链表，输出该链表中倒数第k个节点。为了符合大多数人的习惯，本题从1开始计数，即链表的尾节点是倒数第1个节点。例如，一个链表有6个节点，从头节点开始，它们的值依次是1、2、3、4、5、6。这个链表的倒数第3个节点是值为4的节点。

示例：

给定一个链表: 1->2->3->4->5, 和 k = 2.

返回链表 4->5.

参考：https://leetcode-cn.com/problems/lian-biao-zhong-dao-shu-di-kge-jie-dian-lcof/solution/mian-shi-ti-22-lian-biao-zhong-dao-shu-di-kge-j-11/

"""
class ListNode:
    def __init__(self, x):
        self.val = x
        self.next = None

class Solution:
    def getKthFromEnd(self, head: ListNode, k: int) -> ListNode:
        former, later = head,head
        for _ in range(k):
            if not former:
                return
            former = former.next
        while former:
            former, later = former.next, later.next
        return later


if __name__ == '__main__':
    pass