Source: https://leetcode.com/problems/convert-sorted-array-to-binary-search-tree/

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

/**
* 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}
*/
// Preorder DFS Approach
// O(N) time, O(log N) space for balanced BST height
var sortedArrayToBST = function(nums) {
 const buildTree = (left, right) => {
   if (left > right) {
     return null;
   }
   
   const rootIndex = Math.floor((left + right) / 2);
   const root = new TreeNode(nums[rootIndex]);
         
   // Recursively build the left and right subtree
   root.left = buildTree(left, rootIndex - 1);
   root.right = buildTree(rootIndex + 1, right);
   
   return root;
 };
 
 return buildTree(0, nums.length - 1);
};