题解 | #输出单向链表中倒数第k个结点#

import sys

class Node(object):

    def __init__(self, val=0):
        self.val = val
        self.next = None


while 1:
    line = sys.stdin.readline().strip()
    if line == '': break
    arr = list(map(int, sys.stdin.readline().strip().split(' ')))
    k = int(sys.stdin.readline().strip())

    # 正序构造链表
    head = Node()
    p = q = head
    for a in arr:
        p = Node(a)
        q.next = p
        q = p
    
    # p q 指向头结点
    p = q = head.next
    # q 向后移动k个结点
    for i in range(k):
        q = q.next
    # p q 同时向后移动，直到q到链表尾，此时p指向倒数第k个结点
    while q:
        p = p.next
        q = q.next
    
    print(p.val)