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
        visited=set()
        while pHead:
            if pHead not in visited:
                visited.add(pHead)
                pHead=pHead.next
            else:
                break
        return pHead