题解 | #链表中环的入口结点#
链表中环的入口结点
https://www.nowcoder.com/practice/253d2c59ec3e4bc68da16833f79a38e4
# -*- coding:utf-8 -*-
# class ListNode:
# def __init__(self, x):
# self.val = x
# self.next = None
# 用集合判断是否重复访问，若重复访问该节点，则其为循环入口
class Solution:
def EntryNodeOfLoop(self, pHead):
# write code here
this = pHead
visit = {pHead}
while this:
this = this.next
if this in visit:
return this
visit.add(this)
return None
