/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode() {}
 *     TreeNode(int val) { this.val = val; }
 *     TreeNode(int val, TreeNode left, TreeNode right) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */
class Solution {
    private TreeNode buildBSTFromSortedArray(int[] nums, int lower, int upper) {
        if (lower > upper) {
            return null;
        }

        // Remove Math.ceil to get the other variation
        int mid = (int) Math.ceil((lower + upper) / 2.0);
        TreeNode newTreeNode = new TreeNode(nums[mid]);

        newTreeNode.left = buildBSTFromSortedArray(nums, lower, mid - 1);
        newTreeNode.right = buildBSTFromSortedArray(nums, mid + 1, upper);

        return newTreeNode;
    }

    public TreeNode sortedArrayToBST(int[] nums) {
        return buildBSTFromSortedArray(nums, 0, nums.length - 1);
    }
}