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
        List=[]
        p=pHead
        while p:
            if p in List:
                return p
            else:
                List.append(p)
            p=p.next