# 1382. Balance a Binary Search Tree

<https://leetcode.com/problems/balance-a-binary-search-tree>

## Description

Given the `root` of a binary search tree, return *a **balanced** binary search tree with the same node values*. If there is more than one answer, return **any of them**.

A binary search tree is **balanced** if the depth of the two subtrees of every node never differs by more than `1`.

**Example 1:**

![](https://assets.leetcode.com/uploads/2021/08/10/balance1-tree.jpg)

```
**Input:** root = [1,null,2,null,3,null,4,null,null]
**Output:** [2,1,3,null,null,null,4]
**Explanation:** This is not the only correct answer, [3,1,4,null,2] is also correct.
```

**Example 2:**

![](https://assets.leetcode.com/uploads/2021/08/10/balanced2-tree.jpg)

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

**Constraints:**

* The number of nodes in the tree is in the range `[1, 104]`.
* `1 <= Node.val <= 105`

## ac

```java
```