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.
You may serialize the following tree: 1 / \ 2 3 / \ 4 5 as
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.
use bfs to serialize and deserialize
# Definition for a binary tree node. # class TreeNode(object): # def __init__(self, x): # self.val = x # self.left = None # self.right = None class Codec: def serialize(self, root): """Encodes a tree to a single string. :type root: TreeNode :rtype: str """ results = "" if not root: return results queue =  queue.append(root) while queue: size = len(queue) for i in range(0, size): node = queue.pop(0) if not node: results += "None," else: results += str(node.val) + "," queue.append(node.left) queue.append(node.right) return results def deserialize(self, data): """Decodes your encoded data to tree. :type data: str :rtype: TreeNode """ if not data: return None values = data.split(',') root = TreeNode(int(values)) queue =  queue.append(root) i = 1 while queue and i < len(values): node = queue.pop(0) if values[i] != "None": left = TreeNode(int(values[i])) node.left = left queue.append(left) i += 1 if values[i] != "None": right = TreeNode(int(values[i])) node.right = right queue.append(right) i += 1 return root # Your Codec object will be instantiated and called as such: # ser = Codec() # deser = Codec() # ans = deser.deserialize(ser.serialize(root))
- Time complexity: ~N
- Space complexity: ~N