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Python Program To Find the Smallest and Largest Elements in the Binary Search Tree
When it is required to find the smallest and the largest elements in a binary search tree, a binary tree class is created, and methods to add elements to the tree, search for a specific node are defined. An instance of the class is created, and is used with these methods.
Below is a demonstration of the same −
Example
class BST_Node:
def __init__(self, key):
self.key = key
self.left = None
self.right = None
self.parent = None
def insert_elem(self, node):
if self.key > node.key:
if self.left is None:
self.left = node
node.parent = self
else:
self.left.insert_elem(node)
elif self.key < node.key:
if self.right is None:
self.right = node
node.parent = self
else:
self.right.insert_elem(node)
def search_node(self, key):
if self.key > key:
if self.left is not None:
return self.left.search_node(key)
else:
return None
elif self.key < key:
if self.right is not None:
return self.right.search_node(key)
else:
return None
return self
class BSTree:
def __init__(self):
self.root = None
def add_elem(self, key):
new_node = BST_Node(key)
if self.root is None:
self.root = new_node
else:
self.root.insert_elem(new_node)
def search_node(self, key):
if self.root is not None:
return self.root.search_node(key)
def get_smallest_elem(self):
if self.root is not None:
current = self.root
while current.left is not None:
current = current.left
return current.key
def get_largest_elem(self):
if self.root is not None:
current = self.root
while current.right is not None:
current = current.right
return current.key
my_instance = BSTree()
print('Menu (Assume no duplicate keys)')
print('add ')
print('smallest')
print('largest')
print('quit')
while True:
my_input = input('What operation would you perform ? ').split()
operation = my_input[0].strip().lower()
if operation == 'add':
key = int(my_input[1])
my_instance.add_elem(key)
if operation == 'smallest':
smallest = my_instance.get_smallest_elem()
print('The smallest element is : {}'.format(smallest))
if operation == 'largest':
largest = my_instance.get_largest_elem()
print('The largest element is : {}'.format(largest))
elif operation == 'quit':
breakOutput
Menu (Assume no duplicate keys) add <key> smallest largest quit What operation would you perform ? add 5 What operation would you perform ? add 8 What operation would you perform ? add 11 What operation would you perform ? add 0 What operation would you perform ? add 3 What operation would you perform ? smallest The smallest element is : 0 What operation would you perform ? largest The largest element is : 11 What operation would you perform ? quit’
Explanation
The ‘BST_Node’ class with required attributes is created.
It has an ‘init’ function that is used to set the left, right and parent nodes to ‘None’.
It has an ‘insert_element’ method that helps insert an element into the binary tree.
Another method named ‘search_node’ that searches for a specific node in the tree.
Another class named ‘BSTree’ is defined, where the root is set to ‘None’.
A method named ‘add_elem’ is defined that adds elements to the tree.
There is another method named ‘search_node’ that helps search for a specific node in the tree.
Another method named ‘get_smallest_node’ is defined that helps fetch the smallest node in the tree.
Another method named ‘get_largest_node’ is defined that helps fetch the largest node in the tree.
An object of the ‘BSTree’ class is created.
Based on the operation chosen by the user, the operation is performed.
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