题解 | #判断链表中是否有环#

# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None

#
# 
# @param head ListNode类 
# @return bool布尔型
#
class Solution:
    def hasCycle(self , head: ListNode) -> bool:
        fast=slow=head
        while fast!=None and fast.next!=None:
            fast=fast.next.next
            slow=slow.next
            if fast==slow:
                return True

        return False