👀 Views: 27 💬 Answers: 1 📅 Created: 2025-06-05

binary-tree serialization deserialization algorithm Python

I'm attempting to set up I've tried everything I can think of but I'm updating my dependencies and I've looked through the documentation and I'm still confused about After trying multiple solutions online, I still can't figure this out. I'm working on a custom serialization and deserialization mechanism for a binary tree in Python, but I'm encountering unexpected outputs, particularly for sparse trees. My current approach is using a pre-order traversal to serialize the tree into a string format, and I'm using `None` to represent missing nodes. However, when I deserialize the string back into a tree, some nodes seem to be missing or incorrectly placed. Here's the code I have for serialization: ```python class TreeNode: def __init__(self, val=0, left=None, right=None): self.val = val self.left = left self.right = right class BinaryTree: def serialize(self, root): result = [] def preorder(node): if node: result.append(str(node.val)) preorder(node.left) preorder(node.right) else: result.append('None') preorder(root) return ','.join(result) ``` For deserialization, I'm using the following code: ```python def deserialize(self, data): nodes = iter(data.split(',')) def build_tree(): val = next(nodes) if val == 'None': return None node = TreeNode(int(val)) node.left = build_tree() node.right = build_tree() return node return build_tree() ``` The issue arises when I serialize a sparse tree, such as this: ```python # Constructing a sparse tree root = TreeNode(1) root.left = TreeNode(2) root.right = None root.left.left = TreeNode(3) root.left.right = None ``` When I serialize it, I get the output: `"1,2,3,None,None,None"`. But after deserialization, the tree structure is incorrect; the right child of the root is missing. I've tried adding debug statements to print the intermediate results of both serialization and deserialization, but the outputs seem consistent with what I expect. I suspect it may be an issue with how I'm handling the `None` values during deserialization. Is there something I'm missing in the logic that could lead to incorrect tree reconstruction when nodes are sparse? Any insights or suggestions would be greatly appreciated! Thanks in advance! This is my first time working with Python latest. I'm developing on Windows 11 with Python. I'd be grateful for any help. Thanks for your help in advance!