Question

This is a python program. Put comments explaining the code, please.

Suppose you have been tasked with writing a Python program (using linked lists) to keep track of computer equipment. For each piece of equipment, we track its name, purchase date, purchase amount, and quantity on hand. Write a program that completes the following tasks:

allow the user to add a piece of equipment to the front of the list;

allow the user to update the quantity of a piece of equipment;

calculate and display (to the screen) the total value (in dollars) of ALL inventory

Answer 1

Please Refer to the following code:-

# Node class
class Node:
    # Constructor to initialize the node object
    def __init__(self, name, purchase_date, amount, qty):
        # contains data
        self.name = name
        self.purchase_date = purchase_date
        self.amount = amount
        self.qty = qty
        # contains next node
        self.next = None


# This class contains link list operations
class LinkedList:
    # Function to initialize head
    def __init__(self):
        # initializing head to none
        self.head = None

    def insert(self, new_data):
        # Creating object for node
        new_node = Node(*new_data)
        # Pointing next of new node to current head
        new_node.next = self.head
        # shifting head to new node
        self.head = new_node

    def update_qty(self, name, qty):
        # storing head in temp
        temp = self.head
        # looping
        while (temp):
            # checking for name
            if temp.name == name:
                # updating quantity
                temp.qty = qty
                # breaking loop
                break
            # going to next node
            temp = temp.next
        else:
            # if not found
            print("Part Does not exist")

    def calculate(self):
        # intializing sum variable
        s = 0
        # storing current head in temp
        temp = self.head
        # looping in linked list
        while (temp):
            # calculating sum
            s += int(temp.amount) * int(temp.qty)
            # going to next node
            temp = temp.next
        # returning sum
        return s

# initializing linked list object
ll = LinkedList()
# loop
while True:
    # printing menu
    print("1. Add a equipment")
    print("2. update quantity")
    print("3. Calculate value")
    print("Q. quit")
    # taking Choice input
    choice = input("Choose an option:")
    if choice == '1':
        # Taking input of necessary data
        name = input("Enter name of part:")
        date = input("Enter date of part:")
        amount = input("Enter amount:")
        qty = input("Enter Qty:")
        # inserting into linked list
        ll.insert([name, date, amount, qty])
        print("Succesfully inserted")
    elif choice == '2':
        # Taking name and quantity as input
        name = input("Enter name of part:")
        qty = input("Enter Qty:")
        # updating quantity
        ll.update_qty(name, qty)
        print("Succefully Updated")
    elif choice == '3':
        # calculating total value and printing
        print("Total value is $", ll.calculate())
    elif choice.upper() == 'Q':
        # quitting
        print("Thank You,Bye!")
        break
    else:
        # wrong choice
        print('Try Again')

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Output:-

1. Add a equipment
2. update quantity
3. Calculate value
Q. quit
Choose an option:1
Enter name of part:a
Enter date of part:12/01/19
Enter amount:10
Enter Qty:4
Succesfully inserted
1. Add a equipment
2. update quantity
3. Calculate value
Q. quit
Choose an option:2
Enter name of part:a
Enter Qty:5
Succefully Updated
1. Add a equipment
2. update quantity
3. Calculate value
Q. quit
Choose an option:3
Total value is $ 50
1. Add a equipment
2. update quantity
3. Calculate value
Q. quit
Choose an option:q
Thank You,Bye!

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