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:

**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:

**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

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