1 class Solution: 2 def sortedArrayToBST(self, nums: List[int]) -> TreeNode: 3 l,r = 0,len(nums)-1 4 def helper(left,right): 5 root = None 6 if left <= right: 7 mid = left+(right-left+1)//2 8 root = TreeNode(nums[mid]) 9 root.left = helper(left,mid-1) 10 root.right = helper(mid + 1,right) 11 return root 12 return helper(l,r)