Python 3 Linked List Program: 1. Create a class Fruit that has the following var

Question

Python 3 Linked List Program:

1. Create a class Fruit that has the following variables:

Fruit next

Fruit previous

String name

2. Write a program that will:

Create a doubly linked list of Fruits with the following values stored in the variable space name of each node (note that Apple will be the first element in the linked List and Mango the last). Hint: using a list holding the names and a for loop would make this easier.

Apple
Banana
Cantaloupe
Date
Elderberry
Fig
Grape
Honeyberry
Ice Cream Bean
Jostaberry
Kiwi
Lime
Mango

Develop functions that will:

Iterate through (from front to back) the linked list elements printing the values stored in name.

then Iterate through (from back to front) the linked list elements printing the values stored in name.

Ask the user for the name of a new fruit and add a new element (with that fruit stored as name) to the end of the linked list.

Ask the user to enter the name of a fruit and delete the element in the linked list that has the same name (if there is such an element)

Present to the user a menu that will allow them to select one of the options (functions) above.

Explanation / Answer

PROGRAM CODE:

class DList:

   def __init__(self):
       self.head = None
       self.tail = None
       self.size = 0

   def insert(self, data):
       self.size += 1
       if self.head is None:
           self.head = Fruit(data)
           self.tail = self.head
       else:
           p = Fruit(data)
           p.next = self.head
           self.head.previous = p
           self.head = p

   def remove(self, name):
       if self.head is None:
           raise ValueError('Removing off an empty list')
       current = self.head
       if current.name != name:
           for _ in range(self.size):
               if current.next.name != name:
                   current = current.next
               else:
                   break
           p = current.next.next
           if p is None:
               current.next = None
           else:
               current.next = p
               p.previous = current
       else:
           self.head = self.head.next
           self.head.previous = None
       if self.head == None:
           self.tail = None

   def __sizeof__(self):
       return self.size

   def __repr__(self):
       res = '[ '
       current = self.head
       while current is not None:
           res += str(current.name)
           res += ' '
           current = current.next
       res += ']'
       return res

   def reverseList(self):
       res = '[ '
       current = self.tail
       while current is not None:
           res += str(current.name)
           res += ' '
           current = current.previous
       res += ']'
       return res

class Fruit:
   def __init__(self, data):
       if data is None:
           raise ValueError('Node value cannot be None')
       self.name = data
       self.previous = None
       self.next = None

fruits = ["Apple", "Banana", "Cantaloupe", "Date", "Elderberry", "Fig", "Grape", "Honeyberry", "Ice Cream Bean", "Jostaberry", "Kiwi", "Lime", "Mango"]

fruitList = DList()
for i in range(0, len(fruits)):
   fruitList.insert(fruits[i])
print(fruitList)
fruit = input('Enter a fruit to remove: ')
fruitList.remove(fruit)
print(fruitList)
print('List in reverse')
print(fruitList.reverseList())

OUTPUT:

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