Example: Serialize and Deserialize an N‐Ary Tree - rFronteddu/general_wiki GitHub Wiki

import java.util.*;

class Node {
    int val;
    List<Node> children;

    Node(int val) {
        this.val = val;
        this.children = new ArrayList<>();
    }
}

class Codec {

    // Encodes an n-ary tree to a single string.
    public String serialize(Node root) {
        if (root == null) {
            return "";
        }
        StringBuilder sb = new StringBuilder();
        serializeHelper(root, sb);
        return sb.toString();
    }
    
    private void serializeHelper(Node node, StringBuilder sb) {
        if (node == null) {
            return;
        }
        sb.append(node.val).append(",");
        sb.append(node.children.size()).append(",");
        for (Node child : node.children) {
            serializeHelper(child, sb);
        }
    }

    // Decodes your encoded data to tree.
    public Node deserialize(String data) {
        if (data.isEmpty()) {
            return null;
        }
        String[] tokens = data.split(",");
        Queue<String> queue = new LinkedList<>(Arrays.asList(tokens));
        return deserializeHelper(queue);
    }
    
    private Node deserializeHelper(Queue<String> queue) {
        int val = Integer.parseInt(queue.poll());
        int numChildren = Integer.parseInt(queue.poll());
        Node node = new Node(val);
        for (int i = 0; i < numChildren; i++) {
            node.children.add(deserializeHelper(queue));
        }
        return node;
    }
}