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
        node_s = set()
        while cur:
            if cur not in node_s:
                node_s.add(cur)
            else:
                return cur
            cur = cur.next

直接使用一个set来统计即可，非常方便