i want to be able to insert 8 in between 34 and 1 (being nodes n1 and n2) displa

Question

i want to be able to insert 8 in between 34 and 1 (being nodes n1 and n2) display the updated list and delete 7 from the nodes and display the updated list.

class ListNode2:
  
def __init__(self, item = None, leftL = None, rightL = None):

'''creates a ListNode with the specified data value and
two links: to the previous node and to the next node
post: creates a ListNode with the specified data value and links'''
self.item=item
self.leftL=leftL
self.rightL=rightL
  
# put the code here

def __str__(self):
''' for printing the node '''
  
return str(self.item)

def printLR(headNode):
""" prints all elements following right links, starting with the headNode """
node = headNode
  
while node is not None:
print(node.item, end = " ")
node = node.rightL

print("end of linked list")

def printRL(tailNode):
""" generates a list all elements following left links,
starting with the tailNode """
  
node = tailNode
listV = []
  
while node is not None:
listV.append(node.item)
node = node.leftL
  
listV = listV[::-1]
print("here is the list of elements, following left links:",listV)

return listV
  
# Testing
# create a linked list of 5 values: 34, 1, 23, 7, and 10.
# Displays it.

# put the code here, make n1 to be 34, and n5 be 10
n5 = ListNode2(10)
n4= ListNode2(7,n5)
n3 = ListNode2(23,n4)
n2= ListNode2(1,n3)
n1 = ListNode2(34,n2)
# printing all the nodes, one by one, following right links, then left links
printLR(n1)
printLR(n2)
printLR(n3)
printLR(n4)
printLR(n5)
printRL(n1)
##printRL(n2)
##printRL(n3)
##printRL(n4)
##printRL(n5)
# Then insert new value, say 8 between 34 and 1. Display the updated list
print("Inserting 8...")
### put the code here
printLR(n1)
printLR(n2)
printLR(n3)
printLR(n4)
printLR(n5)
printRL(n1)
##printRL(n2)
##printRL(n3)
##printRL(n4)
##printRL(n5)
### Then delete node with value 7, update the links and display the new list.
print("Deleting 7...")
##
### put the code here
printLR(n1)
printLR(n2)
printLR(n3)
printLR(n4)
printLR(n5)
printRL(n1)
##printRL(n2)
##printRL(n3)
##printRL(n4)
##printRL(n5)

Explanation / Answer

class ListNode2:

def __init__(self, item = None, leftL = None, rightL = None):

'''creates a ListNode with the specified data value and

two links: to the previous node and to the next node

post: creates a ListNode with the specified data value and links'''

self.item=item

self.leftL=leftL

self.rightL=rightL

# put the code here

def __str__(self):

''' for printing the node '''

return str(self.item)

def printLR(headNode):

""" prints all elements following right links, starting with the headNode """

node = headNode

while node is not None:

print(node.item, end = " ")

node = node.rightL

print("end of linked list")

def insertMiddle(n,leftNode,rightNode):

print("Insertion In Middle is success")

leftNode.rightL = n

rightNode.leftL = n

def deleteNode(n,headNode):

node = headNode

pre = None

while node is not None:

#start of while

if(node==n):

#start of if

break

#end of if

pre = node

node = node.leftL

#end of while

if(pre==None):

#start of if

headNode = headNode.leftL

#end of if

else:

#start of else

pre.leftL = n.leftL

#end of else

def printRL(tailNode):

""" generates a list all elements following left links,

starting with the tailNode """

node = tailNode

listV = []

while node is not None:

listV.append(node.item)

node = node.leftL

listV = listV[::-1]

print("here is the list of elements, following left links:",listV)

return listV

# Testing

# create a linked list of 5 values: 34, 1, 23, 7, and 10.

# Displays it.

# put the code here, make n1 to be 34, and n5 be 10

n5 = ListNode2(10)

n4= ListNode2(7,n5)

n3 = ListNode2(23,n4)

n2= ListNode2(1,n3)

n1 = ListNode2(34,n2)

# printing all the nodes, one by one, following right links, then left links

printLR(n1)

printLR(n2)

printLR(n3)

printLR(n4)

printLR(n5)

printRL(n1)

##printRL(n2)

##printRL(n3)

##printRL(n4)

##printRL(n5)

# Then insert new value, say 8 between 34 and 1. Display the updated list

print("Inserting 8...")

n6 = ListNode2(8,n2,n1)

insertMiddle(n6,n2,n1)

printLR(n1)

printLR(n2)

printLR(n3)

printLR(n4)

printLR(n5)

printRL(n1)

##printRL(n2)

##printRL(n3)

##printRL(n4)

##printRL(n5)

### Then delete node with value 7, update the links and display the new list.

print("Deleting 7...")

deleteNode(n4,n1)

printRL(n1)

printLR(n1)

printLR(n2)

printLR(n3)

printLR(n4)

printLR(n5)

printRL(n1)

##printRL(n2)

##printRL(n3)

##printRL(n4)

##printRL(n5)

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