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# 606. Construct String from Binary Tree

## Description

Given the `root`

of a binary tree, construct a string consisting of parenthesis and integers from a binary tree with the preorder traversal way, and return it.

Omit all the empty parenthesis pairs that do not affect the one-to-one mapping relationship between the string and the original binary tree.

**Example 1:**

Input:root = [1,2,3,4]Output:"1(2(4))(3)"Explanation:Originally, 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:root = [1,2,3,null,4]Output:"1(2()(4))(3)"Explanation:Almost the same as the first example, except we cannot omit the first parenthesis pair to break the one-to-one mapping relationship between the input and the output.

**Constraints:**

- The number of nodes in the tree is in the range
`[1, 10`

.^{4}] `-1000 <= Node.val <= 1000`