```
# Definition for a binary tree node.
# class TreeNode(object):
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
class Solution(object):
def sortedArrayToBST(self, nums):
"""
:type nums: List[int]
:rtype: TreeNode
"""
if not nums:
return
low = 0
high = len(nums) - 1
if low <= high:
mid = low + (high-low)//2
rootNode = TreeNode(nums[mid])
rootNode.left = self.sortedArrayToBST(nums[:mid])
rootNode.right = self.sortedArrayToBST(nums[mid+1:])
return rootNode
```