README.md

449. 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)

1. Recursion

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

class Codec:

    def serialize(self, root: TreeNode) -> str:
        if not root:
            return ""

        return chr(root.val) \
            + self.serialize(root.left) + self.serialize(root.right)

    def deserialize(self, data: str) -> TreeNode:
        if not data:
            return None

        i = next((i for i in range(len(data)) if data[i] > data[0]), len(data))

        root = TreeNode(ord(data[0]))
        root.left = self.deserialize(data[1:i])
        root.right = self.deserialize(data[i:])

        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