Python Binary Search Tree: Create a Balanced Binary Search Tree (BST) using an sorted array

Last update on April 23 2025 12:49:54 (UTC/GMT +8 hours)

1. Balanced BST Creation

Write a Python program to create a Balanced Binary Search Tree (BST) using an array of elements where array elements are sorted in ascending order.

Pictorial Presentation:

Sample Solution:

Python Code:

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

def sorted_array_to_bst(nums):
    
    if not nums:
        return None
    mid_val = len(nums)//2
    node = TreeNode(nums[mid_val])
    node.left = sorted_array_to_bst(nums[:mid_val])
    node.right = sorted_array_to_bst(nums[mid_val+1:])
    return node

def preOrder(node): 
    if not node: 
        return      
    print(node.val)
    preOrder(node.left) 
    preOrder(node.right)   
    
result = sorted_array_to_bst([1, 2, 3, 4, 5, 6, 7])
preOrder(result)

Sample Output:

4
2
1
3
6
5
7

Flowchart:

For more Practice: Solve these Related Problems:

• Write a Python program to construct a balanced BST from a sorted array and then perform an in-order traversal to confirm the structure.
• Write a Python script to convert a sorted list into a balanced BST and then print the tree level by level using breadth-first search.
• Write a Python program to build a height-balanced BST from a sorted array and then compute its height recursively.
• Write a Python function to generate a balanced BST from a sorted array and then verify its balance property by comparing the heights of left and right subtrees for every node.

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