w3resource
Python Exercises

Python Binary Search Tree: Find the closest value of a target in a given non-empty Binary Search Tree (BST) of unique values

Python Binary Search Tree: Exercise-2 with Solution

Write a Python program to find the closest value of a given target value in a given non-empty Binary Search Tree (BST) of unique values.

Sample Solution:

Python Code:

class TreeNode(object):
    def __init__(self, x):
        self.val = x
        self.left = None
        self.right = None

def closest_value(root, target):
    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))

root = TreeNode(8)  
root.left = TreeNode(5)  
root.right = TreeNode(14) 
root.left.left = TreeNode(4)  
root.left.right = TreeNode(6) 
root.left.right.left = TreeNode(8)  
root.left.right.right = TreeNode(7)  
root.right.right = TreeNode(24) 
root.right.right.left = TreeNode(22)  
    
result = closest_value(root, 19)
print(result)

Sample Output:

22

Flowchart:

Flowchart: Find the closest value of a target in a given non-empty Binary Search Tree of unique values.

Python Code Editor:

Contribute your code and comments through Disqus.

Previous: Write a Python program to create a Balanced Binary Search Tree (BST) using an array (given) elements where array elements are sorted in ascending order.
Next: Write a Python program to check whether a given a binary tree is a valid binary search tree (BST) or not.

What is the difficulty level of this exercise?