3.7 Homework

# Factorial Function (Using Recursion)
def factorial(n):
    # Handle invalid input
    if not isinstance(n, int) or n < 0:
        return "Error: Factorial is only defined for non-negative integers."
    # Base cases: 0! and 1! both return 1
    elif n in (0, 1):
        return 1
    # Recursive case: n! = n * (n - 1)!
    else:
        return n * factorial(n - 1)

# Calculate factorial of a number between 9 and 13
number = 11
result = factorial(number)

# Display the outcome with a message
if isinstance(result, int):
    print(f"The factorial of {number} is {result}.")
else:
    print(result)

# Iterating Over a List (Numbers)
numbers = [1, 2, 3, 4, 5]
for num in numbers:
    print(num)

# Iterating Through a List (Colors) with a Message
colors = ["red", "blue", "green", "yellow"]
for color in colors:
    print(color)

# Using `continue` and `break` in a Loop
numbers = [1, 2, 3, 4, 5]
for num in numbers:
    if num == 3:
        continue  # Skip when the number is 3
    elif num == 5:
        break  # Exit the loop when 5 is encountered
    print(num)