leetcode: 449. Serialize and Deserialize BST

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 search tree. There is no restriction on how your serialization/deserialization algorithm should work. You just need to ensure that a binary search tree can be serialized to a string and this string can be deserialized to the original tree structure.

The encoded string should be as compact as possible.

Note: Do not use class member/global/static variables to store states. Your serialize and deserialize algorithms should be stateless.

class Codec:
    def serialize(self, root):
        if not root:
            return '#'
        return str(root.val) +',' + self.serialize(root.left) +','+ self.serialize(root.right)

    def deserialize(self, x):
        lst = x.split(',')
        return self.deserializeTree(lst)
    def deserializeTree(self, lst):
        if len(lst)<=0:
            return None
        val = lst.pop(0)
        root = None
        if val != '#':
            root = TreeNode(int(val))
            root.left = self.deserializeTree(lst)
            root.right = self.deserializeTree(lst)
        return root