# 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: while head: if head.val == 100001: return True head.val = 100001 head = head.next return False 每访问一个节点标记一下,如果再一...