new_contents: """Leetcode 297. Serialize and Deserialize Binary Tree
  Hard
  
  URL: https://leetcode.com/problems/serialize-and-deserialize-binary-tree/
  
  Serialization is the process of converting a data structure or object into a
  sequence of bits so that it can be stored in a file or memory buffer, or
  transmitted across a network connection link to be reconstructed later in the
  same or another computer environment.
  
  Design an algorithm to serialize and deserialize a binary tree. There is no
  restriction on how your serialization/deserialization algorithm should work.
  You just need to ensure that a binary tree can be serialized to a string and
  this string can be deserialized to the original tree structure.
  
  Example:
  You may serialize the following tree:
      1
     / \
    2   3
       / \
      4   5
  as "[1,2,3,null,null,4,5]"
  Clarification: The above format is the same as how LeetCode serializes a
  binary tree. You do not necessarily need to follow this format, so please be
  creative and come up with different approaches yourself.
  
  Note: Do not use class member/global/static variables to store states. Your
  serialize and deserialize algorithms should be stateless.
  
  Your Codec object will be instantiated and called as such:
  codec = Codec()
  codec.deserialize(codec.serialize(root))
  """
  
  # Definition for a binary tree node.
  class TreeNode(object):
      def __init__(self, val):
          self.val = val
          self.left = None
          self.right = None
  
  class Codec:
  
      def serialize(self, root):
          """Encodes a tree to a single string.
          
          :type root: TreeNode
          :rtype: str
          """
          pass
  
      def deserialize(self, data):
          """Decodes your encoded data to tree.
          
          :type data: str
          :rtype: TreeNode
          """
          pass
  
  
  def main():
      pass
  
  
  if __name__ == '__main__':
      main()
  
subject: Add lc0297_serialize_and_deserialize_binary_tree.py