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 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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Previous: Write a Python program to delete a node with the given key in a given Binary search tree (BST).
Next: Write a Python program to find the kth smallest element in a given a binary search tree.
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Python: Tips of the Day
Find current directory and file's directory:
To get the full path to the directory a Python file is contained in, write this in that file:
import os dir_path = os.path.dirname(os.path.realpath(__file__))
(Note that the incantation above won't work if you've already used os.chdir() to change your current working directory, since the value of the __file__ constant is relative to the current working directory and is not changed by an os.chdir() call.)
To get the current working directory use
import os cwd = os.getcwd()
Documentation references for the modules, constants and functions used above:
- The os and os.path modules.
- The __file__ constant
- os.path.realpath(path) (returns "the canonical path of the specified filename, eliminating any symbolic links encountered in the path")
- os.path.dirname(path) (returns "the directory name of pathname path")
- os.getcwd() (returns "a string representing the current working directory")
- os.chdir(path) ("change the current working directory to path")
Ref: https://bit.ly/3fy0R6m
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