serialize-and-deserialize-binary-tree

Try it on leetcode

Description

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.

Clarification: The input/output 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.

 

Example 1:

Input: root = [1,2,3,null,null,4,5]
Output: [1,2,3,null,null,4,5]

Example 2:

Input: root = []
Output: []

Example 3:

Input: root = [1]
Output: [1]

Example 4:

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

 

Constraints:

• The number of nodes in the tree is in the range [0, 104].
• -1000 <= Node.val <= 1000

Solution(Python)

class Codec:
    def serialize(self, root):
        """
        Encodes a tree to a single string.

        :type root: TreeNode
        :rtype: str
        """
        if not root:
            return "[]"
        res = [root.val]
        q = collections.deque([root])
        while q:
            front = q.popleft()
            res.append("null")
            if front.left:
                q.append(front.left)
                res[-1] = front.left.val
            res.append("null")
            if front.right:
                q.append(front.right)
                res[-1] = front.right.val
        while res and res[-1] == "null":
            res.pop()

        return ",".join(map(str, res))

    def deserialize(self, data):
        """Decodes your encoded data to tree.

        :type data: str
        :rtype: TreeNode
        """

        if data == "[]":
            return None
        vals = data.split()
        root = TreeNode(vals[0])

        return root