from typing import List, Optional
from tree import TreeNode


class Solution:
    def sortedArrayToBST(self, nums: List[int]) -> Optional[TreeNode]:
        if not nums:
            return
        mid = len(nums) // 2
        root = TreeNode(nums[mid])

        if mid == 0:
            return root

        root.left = self.sortedArrayToBST(nums[:mid])
        root.right = self.sortedArrayToBST(nums[mid + 1:])

        return root