Question

USING IDLE PYTHON:

A greengrocer would like to maintain a linked lists about his products. For each product he saves it name, price and stock amount.

Write a program that creates an empty linked list and then prompts to user to do one of the following:

1. Add a product to the list (anywhere)

2. Print all products in the LinkedList

3. Print all products above a certain price

4. Print all low-stock products ( Less than 20 pounds)

5. Exit

Hint: The trick here is to make a node with 4 parts: one for the produce name, one for the price, one for the stock and one a ref to the next node.

class Node:

     def __init__(self, nm, pr, st):

         self.name = nm

         self.price = pr

         self.stock = st

         self.ref = None

Answer 1

The program is given below:that display menu to user if user choose 1 then add product to the end of the list. if user choose option 2 then print all products in the linked list. if user choose option 3 then print all products that are above certain price. if user choose option 4 then print all products that are less than 20 price. if user choose 5 then exit. and if user choose any other option then it continue to ask until you enter valid option.

class Node:

    #singly linked node

    def __init__(self,nm,pr,st):

        self.name=nm

        self.price=pr

        self.stock=st

        self.ref=None

class linked_list:

    def __init__(self):

        #empty list

        self.tail = None

        self.head = None

        self.count = 0

    def print_all_products(self):

        # Iterate through the list and print all products.

        c_item = self.tail

        while c_item:

            name1=c_item.name

            price1=c_item.price

            stock1=c_item.stock

            c_item = c_item.ref

            print("Name: ",name1,"Price: ",price1,"Stock: ",stock1)

    def print_all_products_above_given_price(self,certain_price):

        # Iterate through the list and print all products above certain price.

        c_item = self.tail

        while c_item:

            if(c_item.price>certain_price):

                    name1=c_item.name

                    price1=c_item.price

                    stock1=c_item.stock

                    c_item = c_item.ref

                    print("Name: ",name1,"Price: ",price1,"Stock: ",stock1)

            else:

                    c_item=c_item.ref

    def print_all_low_products(self):

        # Iterate through the list and print all products less than 20 price.

        c_item = self.tail

        while c_item:

            if (c_item.price<20):

                    name1=c_item.name

                    price1=c_item.price

                    stock1=c_item.stock

                    c_item = c_item.ref

                    print("Name: ",name1,"Price: ",price1,"Stock: ",stock1)

            else:

                    c_item = c_item.ref

    def add_item_to_end(self,nm,pr,st):

        #add items to the end of the list

        node = Node(nm,pr,st)

        if self.head:

            self.head.ref=node

            self.head = node

        else:

            self.tail = node

            self.head = node

        self.count += 1

item = linked_list()

ch=0

while ch!=5:

    print("\n1. Add product to the list")

    print("2. Print all products in the LinkedList")

    print("3. Print all products above certain price")

    print("4. Print all low-stock products (Less than 20 pounds)")

    print("5. Exit")

    ch=int(input(""))

    if(ch==1):

        name=input("Enter name: ")

        price=float(input("Enter Price: "))

        stock=float(input("Enter Stock: "))

        item.add_item_to_end(name,price,stock)

    elif(ch==2):

        item.print_all_products()

    elif(ch==3):

        certain_price=float(input("Enter price to print all product above this given price: "))   

        item.print_all_products_above_given_price(certain_price)

    elif(ch==4):

        item.print_all_low_products()

The screenshot of code is given below:

Output: