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# 0655. Print Binary Tree

<https://leetcode.com/problems/print-binary-tree>

## Description

Given the `root` of a binary tree, construct a **0-indexed** `m x n` string matrix `res` that represents a **formatted layout** of the tree. The formatted layout matrix should be constructed using the following rules:

* The **height** of the tree is `height` and the number of rows `m` should be equal to `height + 1`.
* The number of columns `n` should be equal to `2height+1 - 1`.
* Place the **root node** in the **middle** of the **top row** (more formally, at location `res[0][(n-1)/2]`).
* For each node that has been placed in the matrix at position `res[r][c]`, place its **left child** at `res[r+1][c-2height-r-1]` and its **right child** at `res[r+1][c+2height-r-1]`.
* Continue this process until all the nodes in the tree have been placed.
* Any empty cells should contain the empty string `""`.

Return *the constructed matrix* `res`.

**Example 1:**

![](https://assets.leetcode.com/uploads/2021/05/03/print1-tree.jpg)

```
**Input:** root = [1,2]
**Output:** 
[["","1",""],
 ["2","",""]]
```

**Example 2:**

![](https://assets.leetcode.com/uploads/2021/05/03/print2-tree.jpg)

```
**Input:** root = [1,2,3,null,4]
**Output:** 
[["","","","1","","",""],
 ["","2","","","","3",""],
 ["","","4","","","",""]]
```

**Constraints:**

* The number of nodes in the tree is in the range `[1, 210]`.
* `-99 <= Node.val <= 99`
* The depth of the tree will be in the range `[1, 10]`.

## ac

```java
```