serialize-and-deserialize-bst

https://leetcode.com/problems/serialize-and-deserialize-bst/

1. 用到Java Queue接口，

// LinkedList实现了Queue接口, ArrayList没有实现

2. 用的Java String.split 函数得到 String数组。

3. 另外一个bug是因为String比较用的 == ，没有用 equals

 

package com.company;

import apple.laf.JRSUIUtils;

import java.util.*;

class TreeNode {
    int val;
    TreeNode left;
    TreeNode right;
    TreeNode(int x) { val = x; }
}

class Codec {
    // Encodes a tree to a single string.
    public String serialize(TreeNode root) {
        StringBuilder sb = new StringBuilder();
        if (root == null) {
            return "";
        }

        // LinkedList实现了Queue接口, ArrayList没有实现
        Queue<TreeNode> qe= new LinkedList<>();
        qe.offer(root);
        sb.append(root.val+",");
        while (!qe.isEmpty()) {
            TreeNode tn = qe.poll();
            if (tn.left != null) {
                sb.append(tn.left.val+",");
                qe.offer(tn.left);
            }
            else {
                sb.append(",");
            }
            if (tn.right != null) {
                sb.append(tn.right.val+",");
                qe.offer(tn.right);
            }
            else {
                sb.append(",");
            }
        }
        return sb.toString();
    }

    // Decodes your encoded data to tree.
    public TreeNode deserialize(String data) {
        if (data.equals("")) {
            return null;
        }

        String[] strs = data.split(",");
        Queue<TreeNode> qe = new LinkedList<>();

        if (strs.length < 1 || strs[0].equals("")) {
            return null;
        }

        TreeNode root = new TreeNode(Integer.valueOf(strs[0]));
        qe.offer(root);
        int i = 1;
        while (!qe.isEmpty()) {
            TreeNode tn = qe.poll();

            if (strs.length > i && !strs[i].equals("")) {
                TreeNode left = new TreeNode(Integer.valueOf(strs[i]));
                tn.left = left;
                qe.offer(left);
            }
            i++;
            if (strs.length > i && !strs[i].equals("")) {
                TreeNode right = new TreeNode(Integer.valueOf(strs[i]));
                tn.right = right;
                qe.offer(right);
            }
            i++;
        }
        return root;
    }
}

public class Main {

    public static void main(String[] args) throws InterruptedException {

        System.out.println("Hello!");
        //Solution solution = new Solution();

        // Your Codec object will be instantiated and called as such:
        TreeNode tn = new TreeNode(2);
        TreeNode tn1 = new TreeNode(1);
        //TreeNode tn2 = new TreeNode(3);
        tn.left = tn1;
        //tn.right = tn2;
        Codec codec = new Codec();
        String code = codec.serialize(tn);
        System.out.printf("code:%s\n", code);
        TreeNode ret = codec.deserialize(code);
        System.out.printf("root:%d\n", ret.val);

        System.out.println();

    }
}