system-design-primer

B4/Solutions/object_oriented_design/Media_streaming_service/features.text

@@ -0,0 +1,24 @@
+
+1. User Class:
+
+    a. Represents a user of the streaming service.
+    b. Can create playlists and receive content recommendations based on their playlists.
+
+2. Subscription Class:
+
+    a. Represents a user's subscription type and monthly fee.
+
+3. Media Class:
+
+    a. Represents a media item (e.g., a movie or song) with attributes like title, genre, and play count.
+    b. Includes a method to play the media, which increments the play count.
+
+4. Playlist Class:
+
+    a. Represents a user-created playlist that can hold multiple media items.
+    b. Includes methods to add media to the playlist and display the playlist.
+
+5. MediaLibrary Class:
+
+    a. Manages the collection of media items available for streaming.
+    b. Includes methods to add media to the library and provide recommendations based on user playlists.

B4/Solutions/object_oriented_design/Media_streaming_service/media.py

@@ -0,0 +1,92 @@
+class User:
+    def __init__(self, user_id, name, subscription):
+        self.user_id = user_id
+        self.name = name
+        self.subscription = subscription
+        self.playlists = []
+
+    def create_playlist(self, playlist_name):
+        playlist = Playlist(playlist_name)
+        self.playlists.append(playlist)
+        print(f"Playlist '{playlist_name}' created for {self.name}.")
+
+    def recommend_content(self, media_library):
+        recommendations = media_library.get_recommendations(self)
+        print(f"Recommendations for {self.name}: {', '.join(recommendations)}")
+
+class Subscription:
+    def __init__(self, subscription_type, monthly_fee):
+        self.subscription_type = subscription_type
+        self.monthly_fee = monthly_fee
+
+class Media:
+    def __init__(self, media_id, title, genre):
+        self.media_id = media_id
+        self.title = title
+        self.genre = genre
+        self.play_count = 0
+
+    def play(self):
+        self.play_count += 1
+        print(f"Playing '{self.title}'.")
+
+class Playlist:
+    def __init__(self, name):
+        self.name = name
+        self.media_items = []
+
+    def add_media(self, media):
+        self.media_items.append(media)
+        print(f"Added '{media.title}' to playlist '{self.name}'.")
+
+    def show_playlist(self):
+        print(f"Playlist '{self.name}': {[media.title for media in self.media_items]}")
+
+class MediaLibrary:
+    def __init__(self):
+        self.media_collection = []
+
+    def add_media(self, media):
+        self.media_collection.append(media)
+        print(f"Media '{media.title}' added to the library.")
+
+    def get_recommendations(self, user):
+        # Simple recommendation based on genres of user's playlists
+        recommended = []
+        for playlist in user.playlists:
+            for media in playlist.media_items:
+                if media.genre not in recommended:
+                    recommended.append(media.genre)
+
+        # Return a list of media titles from the library that match recommended genres
+        recommendations = [media.title for media in self.media_collection if media.genre in recommended]
+        return recommendations[:5]  # Limit to 5 recommendations
+
+# Example Usage
+# Create media library and add media
+media_library = MediaLibrary()
+media_library.add_media(Media(1, "Inception", "Sci-Fi"))
+media_library.add_media(Media(2, "Titanic", "Romance"))
+media_library.add_media(Media(3, "The Matrix", "Sci-Fi"))
+media_library.add_media(Media(4, "The Godfather", "Crime"))
+media_library.add_media(Media(5, "Interstellar", "Sci-Fi"))
+
+# Create a subscription
+basic_subscription = Subscription("Basic", 9.99)
+
+# Create a user
+user1 = User(1, "Alice", basic_subscription)
+
+# User creates a playlist and adds media
+user1.create_playlist("Favorites")
+user1.playlists[0].add_media(media_library.media_collection[0])  # Inception
+user1.playlists[0].add_media(media_library.media_collection[2])  # The Matrix
+
+# Show the user's playlist
+user1.playlists[0].show_playlist()
+
+# Get recommendations for the user
+user1.recommend_content(media_library)
+
+# Play a media item
+media_library.media_collection[0].play()  # Play Inception

B4/Solutions/object_oriented_design/banking_system/banking.py

@@ -0,0 +1,62 @@
+class Account:
+    def __init__(self, account_number, account_holder, balance=0):
+        self.account_number = account_number
+        self.account_holder = account_holder
+        self.balance = balance
+
+    def deposit(self, amount):
+        self.balance += amount
+        print(f"Deposited {amount}. New balance: {self.balance}")
+
+    def withdraw(self, amount):
+        if amount > self.balance:
+            print("Insufficient funds.")
+        else:
+            self.balance -= amount
+            print(f"Withdrawn {amount}. New balance: {self.balance}")
+
+    def get_balance(self):
+        return self.balance
+
+class Transaction:
+    def __init__(self, transaction_id, account, amount, transaction_type):
+        self.transaction_id = transaction_id
+        self.account = account
+        self.amount = amount
+        self.transaction_type = transaction_type
+
+    def execute(self):
+        if self.transaction_type == "deposit":
+            self.account.deposit(self.amount)
+        elif self.transaction_type == "withdraw":
+            self.account.withdraw(self.amount)
+        else:
+            print("Invalid transaction type.")
+
+class Bank:
+    def __init__(self):
+        self.accounts = {}
+
+    def create_account(self, account_number, account_holder):
+        if account_number not in self.accounts:
+            self.accounts[account_number] = Account(account_number, account_holder)
+            print(f"Account created for {account_holder}.")
+        else:
+            print("Account already exists.")
+
+    def get_account(self, account_number):
+        return self.accounts.get(account_number, None)
+
+# Example Usage
+bank = Bank()
+bank.create_account("123456", "Alice")
+bank.create_account("789012", "Bob")
+
+alice_account = bank.get_account("123456")
+transaction1 = Transaction(1, alice_account, 1000, "deposit")
+transaction1.execute()
+
+transaction2 = Transaction(2, alice_account, 500, "withdraw")
+transaction2.execute()
+
+print(f"Alice's balance: {alice_account.get_balance()}")

B4/Solutions/object_oriented_design/banking_system/features.text

@@ -0,0 +1,9 @@
+Banking System:
+
+1. Account: Represents a bank account, with methods to deposit, 
+    withdraw, and check the balance.
+
+2. Transaction: Represents a transaction, which can either be a 
+    deposit or withdrawal.
+
+3. Bank: Manages accounts and allows for account creation.

B4/Solutions/object_oriented_design/food_delivery/features.text

@@ -0,0 +1,14 @@
+Features of this Food Delivery System:
+
+1. Customer Class: Represents a customer with attributes like name, address, and phone number.
+
+2. Restaurant Class: Represents a restaurant with a menu. It allows the system to show available 
+   items and get the price of food.
+
+3. DeliveryPerson Class: Represents a delivery person who is assigned to deliver an order.
+
+4. Order Class: Represents an order with details like the customer, restaurant, and the food 
+    item ordered. It also includes the price of the order.
+
+5. FoodDeliverySystem Class: This is the core of the system. It manages customers, restaurants, 
+    delivery personnel, and the order placement process. It assigns a delivery person to each order.

B4/Solutions/object_oriented_design/food_delivery/food_delivery.py

@@ -0,0 +1,134 @@
+class Customer:
+    def __init__(self, name, address, phone):
+        self.name = name
+        self.address = address
+        self.phone = phone
+
+    def __str__(self):
+        return f"Customer: {self.name}, Address: {self.address}, Phone: {self.phone}"
+
+
+class Restaurant:
+    def __init__(self, name, menu):
+        self.name = name
+        self.menu = menu  # menu is a dictionary with item names as keys and prices as values
+
+    def show_menu(self):
+        print(f"Menu for {self.name}:")
+        for item, price in self.menu.items():
+            print(f"{item}: ${price:.2f}")
+
+    def get_price(self, item):
+        return self.menu.get(item, None)
+
+    def __str__(self):
+        return f"Restaurant: {self.name}"
+
+
+class DeliveryPerson:
+    def __init__(self, name):
+        self.name = name
+
+    def deliver(self, customer, order):
+        print(f"{self.name} is delivering {order.food_item} to {customer.name} at {customer.address}")
+
+    def __str__(self):
+        return f"Delivery Person: {self.name}"
+
+
+class Order:
+    def __init__(self, customer, restaurant, food_item):
+        self.customer = customer
+        self.restaurant = restaurant
+        self.food_item = food_item
+        self.price = self.restaurant.get_price(food_item)
+
+    def display_order_details(self):
+        print(f"Order Details: \nCustomer: {self.customer.name}\nFood Item: {self.food_item}\n"
+              f"Price: ${self.price:.2f}\nRestaurant: {self.restaurant.name}")
+
+    def __str__(self):
+        return f"Order: {self.food_item} from {self.restaurant.name} for {self.customer.name}"
+
+
+class FoodDeliverySystem:
+    def __init__(self):
+        self.customers = []
+        self.restaurants = []
+        self.delivery_people = []
+
+    def add_customer(self, customer):
+        self.customers.append(customer)
+
+    def add_restaurant(self, restaurant):
+        self.restaurants.append(restaurant)
+
+    def add_delivery_person(self, delivery_person):
+        self.delivery_people.append(delivery_person)
+
+    def place_order(self, customer, restaurant, food_item):
+        if food_item not in restaurant.menu:
+            print(f"Sorry, {food_item} is not available at {restaurant.name}.")
+            return None
+
+        order = Order(customer, restaurant, food_item)
+        order.display_order_details()
+        delivery_person = self.assign_delivery_person()
+        if delivery_person:
+            delivery_person.deliver(customer, order)
+        return order
+
+    def assign_delivery_person(self):
+        if not self.delivery_people:
+            print("No delivery person available at the moment.")
+            return None
+        # Assign the first available delivery person
+        return self.delivery_people[0]
+
+    def show_restaurants(self):
+        for restaurant in self.restaurants:
+            print(restaurant)
+
+    def show_customers(self):
+        for customer in self.customers:
+            print(customer)
+
+
+# Example usage
+if __name__ == "__main__":
+    # Initialize the system
+    delivery_system = FoodDeliverySystem()
+
+    # Create some customers
+    customer1 = Customer("Alice", "123 Main St", "555-1234")
+    customer2 = Customer("Bob", "456 Oak St", "555-5678")
+
+    # Add customers to the system
+    delivery_system.add_customer(customer1)
+    delivery_system.add_customer(customer2)
+
+    # Create some restaurants with menus
+    pizza_place = Restaurant("Pizza Place", {"Pizza": 10.99, "Burger": 7.99, "Pasta": 8.99})
+    sushi_spot = Restaurant("Sushi Spot", {"Sushi Roll": 12.99, "Tempura": 9.99, "Miso Soup": 3.99})
+
+    # Add restaurants to the system
+    delivery_system.add_restaurant(pizza_place)
+    delivery_system.add_restaurant(sushi_spot)
+
+    # Create a delivery person
+    delivery_person1 = DeliveryPerson("John")
+
+    # Add delivery person to the system
+    delivery_system.add_delivery_person(delivery_person1)
+
+    # Display available restaurants
+    print("Available Restaurants:")
+    delivery_system.show_restaurants()
+
+    # Customer places an order
+    print("\nCustomer 1 places an order:")
+    delivery_system.place_order(customer1, pizza_place, "Pizza")
+
+    # Another customer places an order
+    print("\nCustomer 2 places an order:")
+    delivery_system.place_order(customer2, sushi_spot, "Sushi Roll")

B4/Solutions/object_oriented_design/hotel_booking/features.text

@@ -0,0 +1,22 @@
+Explanation
+
+1. Room Class:
+
+    a. Represents a hotel room with attributes for room number, type, price, and availability.
+    b. Methods include book_room (to book the room) and release_room (to make the room available again).
+
+2. Customer Class:
+
+    a. Represents a customer who can book rooms.
+    b. Includes a method make_booking that attempts to book a room and create a Booking object if successful.
+
+3. Booking Class:
+
+    a. Represents a booking made by a customer.
+    b. Calculates total price based on the duration of the stay and the room price.
+    c. Includes a method cancel_booking to release the room and remove the booking from the customer’s list.
+
+4. Hotel Class:
+
+    a. Manages the collection of rooms.
+    b. Provides methods to add rooms, search for available rooms, and display all rooms.