题解 | #链表中环的入口结点#

# -*- coding:utf-8 -*-
# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None
class Solution:
    def EntryNodeOfLoop(self, pHead):
        # write code here

        cur = pHead
        if not cur:
            return None
        #列表缓存法
        list1 = []
        while cur:
            if cur not in list1:
                list1.append(cur)
            else:
                return cur
            cur = cur.next
        return None