← Computer Programming II

Problem 1 (Easy): Cold Check (<)

You are building a weather app. Create a Temperature class that lets you compare temperatures using <.

  1. Create a Temperature class with a celsius attribute
  2. Add __str__ that returns the temperature like "15°C"
  3. Add a magic method so < works between two Temperature objects (hint: use __lt__)

Input

t1 = Temperature(15)
t2 = Temperature(30)
print(t1 < t2)
print(t2 < t1)
print(t1)

Expected Output

True
False
15°C
Problem 2 (Easy): Weight Limit (<=)

A delivery company checks if a package is within the weight limit. Create a Package class that supports <=.

  1. Create a Package class with a weight attribute (in kg)
  2. Add __str__ that returns like "Package(5kg)"
  3. Add a magic method so <= works between two packages (hint: use __le__)

Input

p1 = Package(5)
p2 = Package(10)
p3 = Package(5)
print(p1 <= p2)
print(p2 <= p1)
print(p1 <= p3)

Expected Output

True
False
True
Problem 3 (Easy): Spice Battle (>)

A cooking app ranks dishes by spice level. Create a Dish class that supports >.

  1. Create a Dish class with name and spice_level attributes
  2. Add __str__ that returns like "Pizza (spice: 3)"
  3. Add a magic method so > works between two dishes (hint: use __gt__)

Input

d1 = Dish("Pizza", 3)
d2 = Dish("Curry", 8)
print(d1 > d2)
print(d2 > d1)
print(d1)

Expected Output

False
True
Pizza (spice: 3)
Problem 4 (Easy): Age Check (>=)

A website checks if a user is old enough. Create a User class that supports >=.

  1. Create a User class with name and age attributes
  2. Add __str__ that returns like "Alisher (age 20)"
  3. Add a magic method so >= works between two users (hint: use __ge__)

Input

u1 = User("Alisher", 20)
u2 = User("Bobur", 17)
u3 = User("Charos", 20)
print(u1 >= u2)
print(u2 >= u1)
print(u1 >= u3)

Expected Output

True
False
True
Problem 5 (Easy+): Color Match (!=)

A design tool checks if two colors are different. Create a Color class that supports !=.

  1. Create a Color class with r, g, b attributes (red, green, blue values)
  2. Add __str__ that returns like "Color(255, 0, 0)"
  3. Add a magic method so != works between two colors (hint: use __ne__)

Input

c1 = Color(255, 0, 0)
c2 = Color(0, 0, 255)
c3 = Color(255, 0, 0)
print(c1 != c2)
print(c1 != c3)
print(c1)

Expected Output

True
False
Color(255, 0, 0)
Problem 6 (Easy+): Movie Queue ([])

You have a movie watch list. Create a MovieQueue class that lets you access movies by position using [].

  1. Create a MovieQueue class that starts with an empty list of movies
  2. Add an add(movie) method to add a movie name to the list
  3. Add __str__ that returns like "MovieQueue: 3 movies"
  4. Add a magic method so [] works to get a movie by its position (hint: use __getitem__)

Input

q = MovieQueue()
q.add("Inception")
q.add("Interstellar")
q.add("The Matrix")
print(q[0])
print(q[2])
print(q)

Expected Output

Inception
The Matrix
MovieQueue: 3 movies
Problem 7 (Medium): Time Tracker

You are building a study tracker app. Students log how many minutes they studied. Create a Duration class that makes working with time feel natural.

  1. The class stores time as total minutes
  2. When printed, show time in a human-readable format: "1h 30m"
  3. You should be able to add two durations together using + — the result is a new Duration
  4. You should be able to check which duration is longer using >
  5. A zero-minute duration should be “falsy” when used in an if statement (like how an empty list is falsy)

Input

d1 = Duration(90)
d2 = Duration(45)
d3 = d1 + d2
print(d1)
print(d2)
print(d3)
print(d1 > d2)
d4 = Duration(0)
if not d4:
    print("No time left")

Expected Output

1h 30m
0h 45m
2h 15m
True
No time left
Problem 8 (Medium+): Shopping Cart

You are building an online store. Create a ShoppingCart class that feels natural to use — you should be able to check its size, access items, merge two carts, compare totals, and print a summary, all using Python’s built-in syntax.

  1. The cart holds items, where each item has a name and a price
  2. Add an add(name, price) method to add an item to the cart
  3. len(cart) should return the number of items
  4. cart[0] should return the first item as a formatted string like "Apple: $2.50" (prices always show 2 decimal places)
  5. cart1 + cart2 should create a new cart containing all items from both carts
  6. cart1 == cart2 should be True if their total prices are the same
  7. print(cart) should display how many items and the total price
  8. An empty cart should be falsy in an if statement

Input

cart1 = ShoppingCart()
cart1.add("Apple", 2.50)
cart1.add("Bread", 3.00)

cart2 = ShoppingCart()
cart2.add("Milk", 4.50)
cart2.add("Eggs", 1.00)

print(len(cart1))
print(cart1[0])
print(cart1)

cart3 = cart1 + cart2
print(cart3)
print(len(cart3))

print(cart1 == cart2)

empty = ShoppingCart()
if not empty:
    print("Cart is empty")

Expected Output

2
Apple: $2.50
ShoppingCart: 2 items, total $5.50
ShoppingCart: 4 items, total $11.00
4
True
Cart is empty
Problem 9 (Advanced): Game Inventory

You are building an RPG game. Create an Inventory class that behaves naturally with Python’s built-in syntax — accessing items, merging inventories, dropping items, and comparing inventories.

  1. An inventory has an owner name and stores items, where each item has a name and a value (in gold). Add an add(name, value) method to add an item to the inventory
  2. You should be able to check how many items are in the inventory and access an item by its position — it should return a string like "Sword (50 gold)"
  3. Printing should show a summary like "Inventory 'Hero': 3 items, total 90 gold"; repr() should show a developer-friendly version like "Inventory('Hero', 3 items)"
  4. Merging two inventories with + should create a new inventory containing all unique items (by name) — no duplicates
  5. Subtracting one inventory from another with - should create a new inventory without the items that appear in the second inventory
  6. Two inventories are equal if they have the same total gold value
  7. An inventory with a higher total gold value is “greater than” another
  8. An empty inventory should be falsy

Input

inv1 = Inventory("Hero")
inv1.add("Sword", 50)
inv1.add("Shield", 30)
inv1.add("Potion", 10)

inv2 = Inventory("Merchant")
inv2.add("Shield", 30)
inv2.add("Bow", 40)

print(len(inv1))
print(inv1[0])
print(inv1)
print(repr(inv1))

inv3 = inv1 + inv2
print(len(inv3))

inv4 = inv1 - inv2
print(len(inv4))
print(inv4[0])

print(inv1 > inv2)

inv5 = Inventory("Traveler")
inv5.add("Ring", 20)
inv5.add("Bow", 50)
print(inv2 == inv5)

empty = Inventory("Goblin")
if not empty:
    print("Inventory is empty")

Expected Output

3
Sword (50 gold)
Inventory 'Hero': 3 items, total 90 gold
Inventory('Hero', 3 items)
4
2
Sword (50 gold)
True
True
Inventory is empty
Problem 10 (Advanced): Grade Book

You are building a school management system. Create a GradeBook class that manages student grades using Python’s built-in syntax.

  1. A gradebook has a subject name and stores student grades as name–grade pairs. Add an add(name, grade) method to record a student’s grade (0–100)
  2. len(gradebook) should return the number of students
  3. gradebook["Harry"] should return Harry’s grade (hint: use __getitem__); raise KeyError if the student is not found
  4. gradebook["Harry"] = 95 should update or set Harry’s grade (hint: use __setitem__)
  5. "Harry" in gradebook should check if a student exists (hint: use __contains__)
  6. gradebook1 + gradebook2 should merge two gradebooks into a new one; if a student appears in both, keep the higher grade
  7. print(gradebook) should show like "GradeBook 'Potions': 3 students, avg 85.7" (average rounded to 1 decimal place)
  8. Two gradebooks are equal if their average grades are the same (rounded to 1 decimal)
  9. An empty gradebook should be falsy
  10. Add a top(n) method that returns a list of the top n student names sorted by grade descending (use sorting and slicing)
  11. Add a passing(min_grade=60) method that returns a list of student names with grades >= min_grade (use a list comprehension)

Input

gb1 = GradeBook("Potions")
gb1.add("Harry", 92)
gb1.add("Ron", 78)
gb1.add("Hermione", 85)

gb2 = GradeBook("Defense Against the Dark Arts")
gb2.add("Ron", 88)
gb2.add("Draco", 95)

print(len(gb1))
print(gb1["Harry"])

gb1["Ron"] = 80
print(gb1["Ron"])

print("Harry" in gb1)
print("Voldemort" in gb1)

gb3 = gb1 + gb2
print(len(gb3))
print(gb3["Ron"])

print(gb1)

print(gb1 == gb2)

empty = GradeBook("Muggle Studies")
if not empty:
    print("No students yet")

print(gb1.top(2))
print(gb1.passing(82))

Expected Output

3
92
80
True
False
4
88
GradeBook 'Potions': 3 students, avg 85.7
False
No students yet
['Harry', 'Hermione']
['Harry', 'Hermione']
Problem 11 (Advanced): Potion Brewing

You are building a potion brewing system for Al-Khogwarts. Create a Potion class that manages ingredients using Python’s built-in syntax.

  1. A potion has a name and stores ingredients as name–quantity pairs. Add an add(ingredient, quantity) method
  2. len(potion) should return the number of ingredients
  3. potion["Moonstone"] should return the quantity of that ingredient; raise KeyError if not found
  4. del potion["Moonstone"] should remove an ingredient from the potion (hint: use __delitem__)
  5. potion * 3 should create a new potion with all quantities tripled
  6. potion1 + potion2 should combine two potions into a new one (using the first potion’s name); if both have the same ingredient, add their quantities together
  7. print(potion) should show like "Potion 'Polyjuice': 3 ingredients, total quantity 6"
  8. repr(potion) should show a developer-friendly version like "Potion('Polyjuice', 3 ingredients)"
  9. Two potions are equal if they have the exact same ingredients with the same quantities
  10. An empty potion (no ingredients) should be falsy
  11. Add a brew() method that returns "Brewing {name} with {n} ingredients..." if the potion has ingredients, or "Nothing to brew!" if empty
  12. Add a needed(other) method that takes another potion and returns a sorted list of ingredient names that are in the other potion but missing from this one (use a list comprehension)

Input

p1 = Potion("Polyjuice")
p1.add("Lacewing Flies", 3)
p1.add("Leeches", 4)
p1.add("Bicorn Horn", 1)
p1.add("Boomslang Skin", 2)

print(len(p1))
print(p1["Lacewing Flies"])

del p1["Leeches"]
print(len(p1))

p2 = p1 * 2
print(p2["Lacewing Flies"])
print(p2["Boomslang Skin"])

p3 = Potion("Felix Felicis")
p3.add("Ashwinder Egg", 1)
p3.add("Squill Bulb", 2)
p3.add("Boomslang Skin", 3)

p4 = p1 + p3
print(len(p4))
print(p4["Boomslang Skin"])

print(p1)
print(repr(p1))

p5 = Potion("Test")
p5.add("Lacewing Flies", 3)
p5.add("Bicorn Horn", 1)
p5.add("Boomslang Skin", 2)
print(p1 == p5)
print(p1 == p3)

empty = Potion("Water")
if not empty:
    print("No ingredients")

print(p1.brew())
print(empty.brew())

print(p1.needed(p3))

Expected Output

4
3
3
6
4
5
5
Potion 'Polyjuice': 3 ingredients, total quantity 6
Potion('Polyjuice', 3 ingredients)
True
False
No ingredients
Brewing Polyjuice with 3 ingredients...
Nothing to brew!
['Ashwinder Egg', 'Squill Bulb']