606. Construct String from Binary Tree（根据二叉树构建字符串）

最新推荐文章于 2022-05-24 18:32:20 发布

原创最新推荐文章于 2022-05-24 18:32:20 发布 · 181 阅读

0 ·

CC 4.0 BY-SA版权

Tree 同时被 3 个专栏收录

84 篇文章

订阅专栏

我的Leetcode专栏

77 篇文章

订阅专栏

温故知新

53 篇文章

订阅专栏

博客围绕从二叉树前序遍历构造字符串展开。题目要求用括号和整数构造字符串，空节点用“()”表示，且要省略不影响字符串与原二叉树一一映射关系的空括号对，还提及了方法思路，但未详细阐述。

题目描述

You need to construct a string consists of parenthesis and integers from a binary tree with the preorder traversing way.
The null node needs to be represented by empty parenthesis pair “()”. And you need to omit all the empty parenthesis pairs that don’t affect the one-to-one mapping relationship between the string and the original binary tree.

在这里插入图片描述

方法思路

public class Solution {
    //Runtime: 10 ms, faster than 79.90%
    //Memory Usage: 40.4 MB, less than 47.41%
    public String tree2str(TreeNode t) {
        if (t == null) return "";
        
        String result = t.val + "";
        
        String left = tree2str(t.left);
        String right = tree2str(t.right);
        
        if (left == "" && right == "") 
            return result;
        if (left == "") 
            return result + "()" + "(" + right + ")";
        if (right == "") 
            return result + "(" + left + ")";
        
        return result + "(" + left + ")" + "(" + right + ")";
    }
}