# Given a non-empty binary search tree and a target value,

# find the value in the BST that is closest to the target.

# Note:

# Given target value is a floating point.

# You are guaranteed to have only one unique value in the BST

# that is closest to the target.

# Definition for a binary tree node.

# class TreeNode(object):

# def __init__(self, x):

# self.val = x

# self.left = None

# self.right = None

def closest_value(root, target):

"""

:type root: TreeNode

:type target: float

:rtype: int

"""

a = root.val

kid = root.left if target < a else root.right

if not kid:

return a

b = closest_value(kid, target)

return min((a, b), key=lambda x: abs(target - x))