added Serialize & Deserialize Binary Tree (Hard)

Author: minhyeong-joe

Hard/SerializeAndDeserializeBinaryTree/README.md

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+# Serialize and Deserialize Binary Tree
+
+[Leetcode Link](https://leetcode.com/problems/serialize-and-deserialize-binary-tree/)
+
+## Problem:
+
+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:
+
+![example](assets/serdeser.jpg)
+
+```
+Input: root = [1,2,3,null,null,4,5]
+Output: [1,2,3,null,null,4,5]
+```
+
+## Note:
+
+- The number of nodes in the tree is in the range [0, 104].
+- -1000 <= Node.val <= 1000

Hard/SerializeAndDeserializeBinaryTree/assets/serdeser.jpg

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+from typing import List
+
+# Definition for a binary tree node.
+
+
+class TreeNode(object):
+ def __init__(self, x, left=None, right=None):
+ self.val = x
+ self.left = left
+ self.right = right
+
+ def __str__(self):
+ tree = list()
+ queue = list()
+ queue.append(self)
+ while queue and not all(node is None for node in queue):
+ currentNode = queue.pop(0)
+ if currentNode is None:
+ tree.append(None)
+ else:
+ tree.append(currentNode.val)
+ queue.append(currentNode.left)
+ queue.append(currentNode.right)
+ return str(tree)
+
+
+class Codec:
+
+ def serialize(self, root):
+ """Encodes a tree to a single string.
+
+ :type root: TreeNode
+ :rtype: str
+ """
+ preorderList = list()
+ self.preorder(root, preorderList)
+ return(str(preorderList))
+
+ def preorder(self, root, preorderList):
+ if root is None:
+ # if preorderList[len(preorderList)-1] is not None:
+ preorderList.append(None)
+ return
+ preorderList.append(root.val)
+ self.preorder(root.left, preorderList)
+ self.preorder(root.right, preorderList)
+
+ def deserialize(self, data):
+ """Decodes your encoded data to tree.
+
+ :type data: str
+ :rtype: TreeNode
+ """
+ data = eval(data)
+ return self.recursiveDeserialize(data)
+
+ def recursiveDeserialize(self, data: List[int]) -> TreeNode:
+ if len(data) <= 0:
+ return
+ currentVal = data.pop(0)
+ if currentVal is None:
+ return
+ root = TreeNode(currentVal)
+ root.left = self.recursiveDeserialize(data)
+ root.right = self.recursiveDeserialize(data)
+ return root
+
+
+# Your Codec object will be instantiated and called as such:
+# ser = Codec()
+# deser = Codec()
+# ans = deser.deserialize(ser.serialize(root))
+
+sol = Codec()
+# generate test tree [1,2,3,null,null,4,5]
+root = TreeNode(1, TreeNode(2), TreeNode(3, TreeNode(4), TreeNode(5)))
+
+print("Original Tree:", root)
+
+ser = sol.serialize(root)
+print("Serialization using preorder:", ser)
+print("Deserialized tree:", sol.deserialize(ser))

Hard/SerializeAndDeserializeBinaryTree/solution.py

@@ -92,6 +92,7 @@ Languages used: Java and Python
  - [Insert Interval](Hard/InsertInterval)
  - [Find Median From Data Stream](Hard/FindMedianFromDataStream)
  - [Escape a Large Maze](Hard/EscapeLargeMaze)
+ - [Serialize and Deserialize Binary Tree](Hard/SerializeAndDeserializeBinaryTree)
 
 ---