Serialize and Deserialize BST

Serialize and Deserialize BST

Serialization is 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 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.

Example 1:

Input: root = [2,1,3]
Output: [2,1,3]

Example 2:

Input: root = []
Output: []

Constraints:

• The number of nodes in the tree is in the range [0, 104].

• 0 <= Node.val <= 104

• The input tree is guaranteed to be a binary search tree.

Solutions

🐍 Python

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

# O(N) Solution with pre-order traversal
# first element is the root,
# all elements that are less than root are left part of tree
# bigger is right, process left and right recursively
class Codec:

    def serialize(self, root: TreeNode) -> str:
        """Encodes a tree to a single string.
        """
        if root is None:
            return ""
        else:
            return str(root.val) + ";" + self.serialize(root.left) + self.serialize(root.right)


    def deserialize(self, data: str) -> TreeNode:
        """Decodes your encoded data to tree.
        """
        if data == "":
            return None

        nodes = data.split(';')
        root = TreeNode(int(nodes[0]))
        root.left = \
            self.deserialize(';'.join([n for n in nodes[1:] if len(n) and int(n) < root.val]))
        root.right = \
            self.deserialize(';'.join([n for n in nodes[1:] if len(n) and int(n) >= root.val]))

        return root



# Your Codec object will be instantiated and called as such:
# Your Codec object will be instantiated and called as such:
# ser = Codec()
# deser = Codec()
# tree = ser.serialize(root)
# ans = deser.deserialize(tree)
# return ans