题解 | #牛牛队列成环#

# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None
#
# 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
#
# 
# @param head ListNode类 
# @return bool布尔型
#
class Solution:
    def hasCycle(self , head: ListNode) -> bool:
        # write code here
        slow = head
        fast = head.next
        while fast and fast.next:
            if slow.val == fast.val:
                return True
            slow = slow.next
            fast = fast.next.next
            
        return False