[LeetCode] 297. 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.
Example:
You may serialize the following tree:
1
/ \
2 3
/ \
4 5
as "[1,2,3,null,null,4,5]"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.
Solution
public class Codec { // Encodes a tree to a single string. public String serialize(TreeNode root) { if (root == null) return "null"; return root.val + "," + serialize(root.left) + "," + serialize(root.right); } // Decodes your encoded data to tree. public TreeNode deserialize(String data) { List<String> values = Arrays.asList(data.split(",")); Queue<String> queue = new LinkedList<>(values); return buildTree(queue); } private TreeNode buildTree(Queue<String> values) { if (values == null || values.size() == 0) return null; String val = values.poll(); if (val.equals("null")) return null; TreeNode node = new TreeNode(Integer.valueOf(val)); node.left = buildTree(values); node.right = buildTree(values); return node; } }