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Serialize and Deserialize Binary Tree

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Design an algorithm to serialize and deserialize a binary tree into a string.

public class Codec {

// Encodes a tree to a single string.

public String serialize(TreeNode root) {
    if(root == null){
        return "";
    return dfs(root);

StringBuilder sb = new StringBuilder();
public String dfs(TreeNode node){
    if(node == null){
        sb.append("null, ");
        return "";
    sb.append(node.val + ", ");
    return sb.toString();

// Decodes your encoded data to tree.
public TreeNode deserialize(String data) {
        return null;
    String arr[] = data.split(", ");
    return construct(arr);

int idx = 0;
public TreeNode construct(String arr[]){
    if(idx >= arr.length || arr[idx].equals("null")){
        return null;
    TreeNode node = new TreeNode(Integer.parseInt(arr[idx++]));
    node.left = construct(arr);
    node.right = construct(arr);
    return node;

Posted by Jamie Meyer 3 months ago

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