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:
        p1 = head
        p2 = head
        n = 10000
        while head and n:
            p1 = p1.next
            if not p2.next:
                return False
            if not p2.next.next:
                return False
            p2 = p2.next.next
            if p1.val == p2.val:
                return True
        return False