import pyutil as pyu
pyu.get_local_pyinfo()

print(pyu.ps2("python-dotenv"))

from typing import List

class Solution:
  def detectCycle(self, head: ListNode) -> ListNode:
    slow = head
    fast = head

    while fast and fast.next:
      slow = slow.next
      fast = fast.next.next
      if slow == fast:
        slow = head
        while slow != fast:
          slow = slow.next
          fast = fast.next
        return slow

    return None

new Solution().detectCycle()