Problems

Time Limit

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BankAccount Class

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Shape Hierarchy

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Employee System

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Problem 1: BankAccount Class

Difficulty: Hard | Topic: Class Design

Description

Create a complete BankAccount class with the following specifications.

Requirements

Constructor (__init__):

Parameters: owner (str), balance (float, default 0)
Store owner and balance as instance attributes
Create a transaction_history list, initially empty

Methods:

deposit(amount): Add amount to balance, record in history, return new balance
withdraw(amount): Subtract amount if sufficient funds, record in history, return new balance or -1 if insufficient
get_balance(): Return current balance
get_history(): Return list of transaction strings

Special Methods:

__str__: Return "Account: {owner}, Balance: ${balance}"

Transaction History Format

Each transaction should be recorded as:

Deposit: "Deposit: +${amount}"
Withdrawal: "Withdrawal: -${amount}"

Example

Usage:

acc = BankAccount("Alice", 100) acc.deposit(50) # Returns 150 acc.withdraw(30) # Returns 120 acc.withdraw(200) # Returns -1 (insufficient) print(acc) # Account: Alice, Balance: $120 acc.get_history() # ["Deposit: +$50", "Withdrawal: -$30"]

solution.py

class BankAccount:
    """A bank account with transaction tracking."""

    def __init__(self, owner, balance=0):
        # Your code here
        pass

    def deposit(self, amount):
        """Add amount to balance and record transaction."""
        # Your code here
        pass

    def withdraw(self, amount):
        """Withdraw amount if sufficient funds."""
        # Your code here
        pass

    def get_balance(self):
        """Return current balance."""
        # Your code here
        pass

    def get_history(self):
        """Return transaction history."""
        # Your code here
        pass

    def __str__(self):
        """String representation."""
        # Your code here
        pass

Hint

Start by storing owner, balance, and an empty list for history. For withdraw, check if amount > self.balance first and return -1 if true. For __str__, use an f-string with the required format.

Output

Run your code to see output...

Problem 2: Shape Hierarchy

Difficulty: Hard | Topic: Inheritance & Polymorphism

Description

Create a shape class hierarchy with a base Shape class and two child classes: Rectangle and Circle.

Shape (Base Class)

__init__(self, name): Store the shape name
area(self): Return 0 (to be overridden)
perimeter(self): Return 0 (to be overridden)
describe(self): Return "{name}: Area={area}, Perimeter={perimeter}"

Rectangle (Child Class)

__init__(self, width, height): Call parent with "Rectangle", store width/height
area(self): Return width × height
perimeter(self): Return 2 × (width + height)

Circle (Child Class)

__init__(self, radius): Call parent with "Circle", store radius
area(self): Return π × radius² (use 3.14159)
perimeter(self): Return 2 × π × radius

Example

Usage:

rect = Rectangle(10, 5) rect.area() # 50 rect.perimeter() # 30 rect.describe() # "Rectangle: Area=50, Perimeter=30" circle = Circle(7) circle.area() # ~153.94 circle.perimeter() # ~43.98

solution.py

class Shape:
    """Base class for shapes."""

    def __init__(self, name):
        # Your code here
        pass

    def area(self):
        # Your code here
        pass

    def perimeter(self):
        # Your code here
        pass

    def describe(self):
        # Your code here
        pass


class Rectangle(Shape):
    """Rectangle shape."""

    def __init__(self, width, height):
        # Your code here
        pass

    def area(self):
        # Your code here
        pass

    def perimeter(self):
        # Your code here
        pass


class Circle(Shape):
    """Circle shape."""

    PI = 3.14159

    def __init__(self, radius):
        # Your code here
        pass

    def area(self):
        # Your code here
        pass

    def perimeter(self):
        # Your code here
        pass

Hint

Use super().__init__("Rectangle") in child classes. The describe method in Shape should call self.area() and self.perimeter() - polymorphism will use the child's versions!

Output

Run your code to see output...

Problem 3: Employee Management System

Difficulty: Hard | Topic: Advanced OOP Design

Description

Create an employee management system with different employee types and a company class to manage them.

Employee (Base Class)

__init__(self, name, base_salary)
calculate_pay(self): Return base_salary
__str__(self): Return "{name} - ${pay}"

Manager (Child of Employee)

__init__(self, name, base_salary, bonus)
calculate_pay(self): Return base_salary + bonus

Developer (Child of Employee)

__init__(self, name, base_salary, projects): projects is int
calculate_pay(self): Return base_salary + (projects × 500)

Company

__init__(self, name): Store name, create empty employees list
add_employee(self, employee): Add to list
total_payroll(self): Sum of all employee pay
get_employees(self): Return list of employee names

Example

Usage:

company = Company("TechCorp") company.add_employee(Employee("Alice", 50000)) company.add_employee(Manager("Bob", 60000, 10000)) company.add_employee(Developer("Charlie", 55000, 3)) company.total_payroll() # 126500 company.get_employees() # ["Alice", "Bob", "Charlie"]

solution.py

class Employee:
    """Base employee class."""

    def __init__(self, name, base_salary):
        # Your code here
        pass

    def calculate_pay(self):
        # Your code here
        pass

    def __str__(self):
        # Your code here
        pass


class Manager(Employee):
    """Manager with bonus pay."""

    def __init__(self, name, base_salary, bonus):
        # Your code here
        pass

    def calculate_pay(self):
        # Your code here
        pass


class Developer(Employee):
    """Developer with project-based bonus."""

    def __init__(self, name, base_salary, projects):
        # Your code here
        pass

    def calculate_pay(self):
        # Your code here
        pass


class Company:
    """Company managing employees."""

    def __init__(self, name):
        # Your code here
        pass

    def add_employee(self, employee):
        # Your code here
        pass

    def total_payroll(self):
        # Your code here
        pass

    def get_employees(self):
        # Your code here
        pass

Hint

Use super().__init__(name, base_salary) in Manager and Developer. For Company, use sum(emp.calculate_pay() for emp in self.employees) for total_payroll. Use a list comprehension for get_employees.

Output

Run your code to see output...

Problem 1: BankAccount Class

Description

Requirements

Transaction History Format

Example

Problem 2: Shape Hierarchy

Description

Shape (Base Class)

Rectangle (Child Class)

Circle (Child Class)

Example

Problem 3: Employee Management System

Description

Employee (Base Class)

Manager (Child of Employee)

Developer (Child of Employee)

Company

Example

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