每日算法题: Create a balanced binary search tree

Hi, here's your problem today. This problem was recently asked by LinkedIn:

Given a sorted list of numbers, change it into a balanced binary search tree. You can assume there will be no duplicate numbers in the list.

Here's a starting point:

from collections import deque



class Node:

  def __init__(self, value, left=None, right=None):

    self.value = value

    self.left = left

    self.right = right



  def __str__(self):

    # level-by-level pretty-printer

    nodes = deque([self])

    answer = ''

    while len(nodes):

      node = nodes.popleft()

      if not node:

        continue

      answer += str(node.value)

      nodes.append(node.left)

      nodes.append(node.right)

    return answer





def createBalancedBST(nums):

  # Fill this in.



print createBalancedBST([1, 2, 3, 4, 5, 6, 7])

# 4261357

#   4

#  / \

# 2   6

#/ \ / \

#1 3 5 7