108.convert-sorted-array-to-binary-search-tree

Given an array where elements are sorted in ascending order, convert it to a height balanced BST.

# 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 nums:
            midPos = len(nums) / 2
            mid = nums[midPos]
            root = TreeNode(mid)
            root.left = self.sortedArrayToBST(nums[:midPos])
            root.right = self.sortedArrayToBST(nums[midPos+1:])
            return root