#Leet Code# Convert Sorted Array to Binary Search Tree

描述：递归

代码：

 class Solution:
     # @param num, a list of integers
     # @return a tree node
     def sortedArrayToBST(self, num):
         if len(num) == 0:
             return None

         mid_index = len(num) / 2

         tmp_tree = TreeNode(num[mid_index])
         tmp_tree.left = self.sortedArrayToBST(num[:mid_index])
         tmp_tree.right = self.sortedArrayToBST(num[mid_index + 1:])

         return tmp_tree