new_contents: """Leetcode 141. Linked List Cycle
  Easy
  
  URL: https://leetcode.com/problems/linked-list-cycle/
  
  Given a linked list, determine if it has a cycle in it.
  
  To represent a cycle in the given linked list, we use an integer pos
  which represents the position (0-indexed) in the linked list where tail connects to.
  If pos is -1, then there is no cycle in the linked list.
  
  Example 1:
  Input: head = [3,2,0,-4], pos = 1
  Output: true
  Explanation: There is a cycle in the linked list,
  where tail connects to the second node.
  
  Example 2:
  Input: head = [1,2], pos = 0
  Output: true
  Explanation: There is a cycle in the linked list,
  where tail connects to the first node.
  
  Example 3:
  Input: head = [1], pos = -1
  Output: false
  Explanation: There is no cycle in the linked list.
  
  Follow up:
  Can you solve it using O(1) (i.e. constant) memory?
  """
  
  # Definition for singly-linked list.
  class ListNode(object):
      def __init__(self, val):
          self.val = val
          self.next = None
  
  
  class Solution(object):
      def hasCycle(self, head):
          """
          :type head: ListNode
          :rtype: bool
          """
          pass
  
  
  def main():
      pass
  
subject: Add lc0141_linked_list_cycle.py