Construct String From Binary Tree
Posted amazingzoe
tags:
篇首语:本文由小常识网(cha138.com)小编为大家整理,主要介绍了Construct String From Binary Tree相关的知识,希望对你有一定的参考价值。
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.
1 /** 2 * Definition for a binary tree node. 3 * public class TreeNode { 4 * int val; 5 * TreeNode left; 6 * TreeNode right; 7 * TreeNode(int x) { val = x; } 8 * } 9 */ 10 public class Solution { 11 public String tree2str(TreeNode t) { 12 if (t == null) return ""; 13 if (t.left == null && t.right == null) return String.valueOf(t.val); 14 15 String leftStr = tree2str(t.left); 16 String rightStr = tree2str(t.right); 17 18 if (t.left == null) return t.val + "()(" + rightStr + ")"; 19 if (t.right == null) return t.val + "(" + leftStr + ")"; 20 return t.val + "(" + leftStr + ")(" + rightStr + ")"; 21 } 22 }
以上是关于Construct String From Binary Tree的主要内容,如果未能解决你的问题,请参考以下文章
LeetCode Construct String from Binary Tree
Construct String From Binary Tree
606. Construct String from Binary Tree
606. Construct String from Binary Tree