leetcood学习笔记-141-环形列表

class Solution(object):
    def hasCycle(self, head):
        """
        :type head: ListNode
        :rtype: bool
        """
        while head:
            if head.val == "daafas":
                return True
            else:
                head.val = "daafas":
            head = head.next
        return False

class Solution(object):
    def hasCycle(self, head):
        """
        :type head: ListNode
        :rtype: bool
        """
        save = set()
        cur = head 
        while cur is not None:
            if cur in save:
                return True
            else:
                save.add(cur)
                cur = cur.next
        return False