# Python Binary Search Tree: Convert a array to Binary Search Tree (BST)

## Python Binary Search Tree: Exercise-5 with Solution

Write a Python program to convert a given array of elements to a height balanced Binary Search Tree (BST).

Note: The selection sort improves on the bubble sort by making only one exchange for every pass through the list.

**Sample Solution**:

**Python Code:**

```
class TreeNode(object):
def __init__(self, x):
self.val = x
self.left = None
self.right = None
def array_to_bst(array_nums):
if not array_nums:
return None
mid_num = len(array_nums)//2
node = TreeNode(array_nums[mid_num])
node.left = array_to_bst(array_nums[:mid_num])
node.right = array_to_bst(array_nums[mid_num+1:])
return node
def preOrder(node):
if not node:
return
print(node.val)
preOrder(node.left)
preOrder(node.right)
array_nums = [1,2,3,4,5,6,7]
print("Original array:")
print(array_nums)
result = array_to_bst(array_nums)
print("\nArray to a height balanced BST:")
print(preOrder(result))
```

Sample Output:

Original array: [1, 2, 3, 4, 5, 6, 7] Array to a height balanced BST: 4 2 1 3 6 5 7 None

**Flowchart: **

**Python Code Editor:**

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