Question

show all steps-python

Review the following BST and create the inorder, preorder and postorder list.

Follow both algorithms.  If the node has a left child and a right child, 1) replace the node’s value with the largest value
in the left subtree and delete that value’s node from the left subtree.

Or 2) replace the node’s value with the smallest value in the right subtree and delete that value’s node from the right subtree.

-What are the two possible values for deleting the root value, 50?

-After deleting the value 72 in the following BST, list the values in preorder traversal.

50) (17 (72) 12 (23 (54) 76 9 14) (19) 67)

Answer 1

#Node class for implementing the BST
class Node: 
    def __init__(self,key):
        self.left = None
        self.right = None
        self.val = key

#Insert function to insert new node into BST
def insert(root,key):
    if root is None:
        return Node(key)
    if(root.val<key):
        root.right = insert(root.right,key)
    elif(root.val>key):
        root.left = insert(root.left,key)
    return root
#inorder tree traversal 
def inorder(root): 
    if root:
        inorder(root.left)
        print(root.val,end=" ")
        inorder(root.right)
#postorder tree traversal
def postOrder(root):
    if root:
        postOrder(root.left)
        postOrder(root.right)
        print(root.val,end=" ")
#preorder tree traversal
def preOrder(root):
    if root:
        print(root.val,end=" ")
        preOrder(root.left)
        preOrder(root.right)
#minimum value of the tree
def minimum(root):
    while(root.left!=None):
        root = root.left
    return root.val
#maximum value of the tree
def maximum(root):
    
    while(root.right!=None):
        root = root.right
    return root.val
#deleting the given value
def deleteNode(root, key):  
    if root is None: 
        return root
    #if the key value is less than root value then
    #it will lies in left subtree
    if key < root.val: 
        root.left = deleteNode(root.left, key) 
    # If the key value is greater than the root value
    # then it will lies in right subtree 
    elif(key > root.val): 
        root.right = deleteNode(root.right, key) 
    #or the key is root value 
    else: 
        # checking for root has one node or not
        if root.left is None : 
            temp = root.right  
            root = None 
            return temp  
              
        elif root.right is None : 
            temp = root.left  
            root = None
            return temp 
  
        #if root has two children
        #then find the minimum value from it's right subtree
        temp = minimum(root.right) 
  
        # Copy the inorder successor's content to this node 
        root.val = temp 
  
        # Delete the inorder successor 
        root.right = deleteNode(root.right , temp) 
    return root 
if __name__=="__main__": 
    
    root = None
    root = insert(root,50)
    root = insert(root,17)
    root = insert(root,12)
    root = insert(root,23)
    root = insert(root,9)
    root = insert(root,14)
    root = insert(root,19)
    root = insert(root,72)
    root = insert(root,54)
    root = insert(root,67)
    root = insert(root,76)
    print("post order:",end=" ")
    postOrder(root)
    print("\npre order:",end=" ")
    preOrder(root)
    print("\nin order:",end=" ")
    inorder(root)
    #finding minimum value of root 50
    print("\nminimum element is:",end=" ")
    print(minimum(root))
    #finding maximum value of root 50
    print("maximum element is:",end=" ")
    print(maximum(root))
    #deleting 72
    root = deleteNode(root,72)
    #After deleting the 72 preorder
    preOrder(root)

Follow the above indentation

The code:

#Node class for implementing the BST
class Node:
def __init__(self,key):
self.left = None
self.right = None
self.val = key

#Insert function to insert new node into BST
def insert(root,key):
if root is None:
return Node(key)
if(root.val<key):
root.right = insert(root.right,key)
elif(root.val>key):
root.left = insert(root.left,key)
return root
#inorder tree traversal
def inorder(root):
if root:
inorder(root.left)
print(root.val,end=" ")
inorder(root.right)
#postorder tree traversal
def postOrder(root):
if root:
postOrder(root.left)
postOrder(root.right)
print(root.val,end=" ")
#preorder tree traversal
def preOrder(root):
if root:
print(root.val,end=" ")
preOrder(root.left)
preOrder(root.right)
#minimum value of the tree
def minimum(root):
while(root.left!=None):
root = root.left
return root.val
#maximum value of the tree
def maximum(root):
  
while(root.right!=None):
root = root.right
return root.val
#deleting the given value
def deleteNode(root, key):
if root is None:
return root
#if the key value is less than root value then
#it will lies in left subtree
if key < root.val:
root.left = deleteNode(root.left, key)
# If the key value is greater than the root value
# then it will lies in right subtree
elif(key > root.val):
root.right = deleteNode(root.right, key)
#or the key is root value
else:
# checking for root has one node or not
if root.left is None :
temp = root.right
root = None
return temp
  
elif root.right is None :
temp = root.left
root = None
return temp
  
#if root has two children
#then find the minimum value from it's right subtree
temp = minimum(root.right)
  
# Copy the inorder successor's content to this node
root.val = temp
  
# Delete the inorder successor
root.right = deleteNode(root.right , temp)
return root
if __name__=="__main__":
  
root = None
root = insert(root,50)
root = insert(root,17)
root = insert(root,12)
root = insert(root,23)
root = insert(root,9)
root = insert(root,14)
root = insert(root,19)
root = insert(root,72)
root = insert(root,54)
root = insert(root,67)
root = insert(root,76)
print("post order:",end=" ")
postOrder(root)
print("\npre order:",end=" ")
preOrder(root)
print("\nin order:",end=" ")
inorder(root)
#finding minimum value of root 50
print("\nminimum element is:",end=" ")
print(minimum(root))
#finding maximum value of root 50
print("maximum element is:",end=" ")
print(maximum(root))
#deleting 72
root = deleteNode(root,72)
#After deleting the 72 preorder
preOrder(root)