Given an integer array `nums` where the elements are sorted in ascending order, convert it to a height-balanced binary search tree.

height-balanced binary tree is a binary tree in which the depth of the two subtrees of every node never differs by more than one.

Example 1:

```Input: nums = [-10,-3,0,5,9]
Output: [0,-3,9,-10,null,5]
Explanation: [0,-10,5,null,-3,null,9] is also accepted:

```

Example 2:

```Input: nums = [1,3]
Output: [3,1]
Explanation: [1,3] and [3,1] are both a height-balanced BSTs.
```

Constraints:

• `1 <= nums.length <= 104`
• `-104 <= nums[i] <= 104`
• `nums` is sorted in a strictly increasing order.

Idea:

Recursion + Divide and Conquer

Time complexity: O(n)
Space complexity: O(logn)

Solution:

``````/**
* Definition for a binary tree node.
* function TreeNode(val, left, right) {
*     this.val = (val===undefined ? 0 : val)
*     this.left = (left===undefined ? null : left)
*     this.right = (right===undefined ? null : right)
* }
*/
/**
* @param {number[]} nums
* @return {TreeNode}
*/
var sortedArrayToBST = function(nums) {
return createBST(nums, 0, nums.length - 1);
};

function createBST(nums, l, r) {
// exit recursion condition
if (l > r) return null;

let mid = l + Math.floor((r - l) / 2);
let root = new TreeNode(nums[mid]);
root.left = createBST(nums, l, mid - 1);
root.right = createBST(nums, mid + 1, r);
return root;
}``````