zoukankan      html  css  js  c++  java
  • LeetCode

    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.

    Example 1:

    Input: Binary tree: [1,2,3,4]
           1
         /   
        2     3
       /    
      4     
    
    Output: "1(2(4))(3)"
    
    Explanation: Originallay it needs to be "1(2(4)())(3()())",
    but you need to omit all the unnecessary empty parenthesis pairs.
    And it will be "1(2(4))(3)".

    Example 2:

    Input: Binary tree: [1,2,3,null,4]
           1
         /   
        2     3
           
          4 
    
    Output: "1(2()(4))(3)"
    
    Explanation: Almost the same as the first example,
    except we can't omit the first parenthesis pair to break the one-to-one mapping relationship between the input and the output.

    /**
     * Definition for a binary tree node.
     * public class TreeNode {
     *     int val;
     *     TreeNode left;
     *     TreeNode right;
     *     TreeNode(int x) { val = x; }
     * }
     */
    public class Solution {
        public String tree2str(TreeNode t) {
            if (t == null)
                return "";
            StringBuilder str = new StringBuilder();
            str.append(t.val);
            
            if (t.left != null || t.right != null) {
                str.append("(" + tree2str(t.left) + ")");
                if (t.right != null)
                str.append("(" + tree2str(t.right) + ")");
            }
            
            return str.toString();
        }
    }
  • 相关阅读:
    Weblogic 部署注意事项
    Can't load IA 32-bit .dll on a AMD 64-bit platform
    getDeclaredFields()和getFields()
    EJB QI查询
    Git for windows 中文乱码解决方案
    gulp browser-sync自动刷新插件
    input默认提示取消
    devDependencies和dependencies的区别
    npm安装插件提示
    gulp.watch监听文件
  • 原文地址:https://www.cnblogs.com/wxisme/p/7300885.html
Copyright © 2011-2022 走看看