Convert Sorted Array to Binary Search Tree

LeetCode 108

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution:
    def sortedArrayToBST(self, nums):
        """
        :type nums: List[int]
        :rtype: TreeNode
        """
        
        if not nums:
            return None
        else:
            mid = len(nums)//2
            root = TreeNode(nums[mid])
            root.left = self.sortedArrayToBST(nums[:mid])
            root.right = self.sortedArrayToBST(nums[mid+1:]) 
            # slice list 的時候若超過會直接給 [] 但若用for-loop 導致超過index 會給出 out of index
            return root