# [LeetCode] 428. Serialize and Deserialize N-ary Tree

linspiration

## 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 an N-ary tree. An N-ary tree is a rooted tree in which each node has no more than N children. There is no restriction on how your serialization/deserialization algorithm should work. You just need to ensure that an N-ary tree can be serialized to a string and this string can be deserialized to the original tree structure.

For example, you may serialize the following `3-ary` tree

as `[1 [3[5 6] 2 4]]`. You do not necessarily need to follow this format, so please be creative and come up with different approaches yourself.

Note:

N is in the range of [1, 1000]
Do not use class member/global/static variables to store states. Your serialize and deserialize algorithms should be stateless.

## Solution

``````class Codec {

// Encodes a tree to a single string.
public String serialize(Node root) {
if (root == null) return null;
serializeHelper(root, list);
return String.join(",", list);
}

private void serializeHelper(Node root, List<String> list) {
if (root == null) return;
for (Node child: root.children) {
serializeHelper(child, list);
}
}

// Decodes your encoded data to tree.
public Node deserialize(String data) {
if (data == null || data.length() == 0) return null;
String[] values = data.split(",");
return deserializeHelper(queue);
}

private Node deserializeHelper(Queue<String> queue) {
Node root = new Node();
root.val = Integer.valueOf(queue.poll());
int size = Integer.valueOf(queue.poll());
root.children = new ArrayList<>();
for (int i = 0; i < size; i++) {