[LeetCode]题解（python）：108-Convert Sorted Array to Binary Search Tree

题目来源：

　　https://leetcode.com/problems/convert-sorted-array-to-binary-search-tree/

　　给出一个排好序的数组，根据这个数据形成一个高度平衡的搜索二叉树。

　　将中位数为根节点，中位数左边为左子树，右边为右子树。

# 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
        """
        size = len(nums)
        if size == 0:
            return None
        if size == 1:
            return TreeNode(nums[0])
        size //= 2
        root = TreeNode(nums[size])
        root.left = self.sortedArrayToBST(nums[:size])
        root.right = self.sortedArrayToBST(nums[size + 1:])
        return root