链表中倒数第k个结点(python)

题目描述

输入一个链表，输出该链表中倒数第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):
        # write code here
        #遍历一次链表获得链表长度，再次遍历链表，至n-k+1出输出
        if head == None or k <= 0:
            return None
        p = head
        n = 1
        while p.next != None:
            p = p.next
            n = n+1
        if k > n:
            return None
        for i in range(n-k):
            head = head.next
        return head