【LeetCode OJ】Convert Sorted Array to Binary Search Tree

Problem Link:

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

Same idea to Convert Sorted Array to Binary Search Tree, but we use a recursive function to construct the binary search tree.

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

class Solution:
    # @param num, a list of integers
    # @return a tree node
    def sortedArrayToBST(self, num):
        n = len(num)
        if n == 0:
            return None
        elif n == 1:
            return TreeNode(num[0])
        mid = n / 2
        root = TreeNode(num[mid])
        root.left = self.sortedArrayToBST(num[:mid])
        root.right = self.sortedArrayToBST(num[mid+1:])
        return root