Debugging mindset in Intro to Computing - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ trace

intermediate

Trace the output of a simple debugging scenario

Consider the following code snippet that calculates the sum of numbers from 1 to 5 but has a subtle bug. What will be the output?

Intro to Computing

total = 0
for i in range(1, 6):
    total += i
print(total)

A 10

B 15

C 0

D 5

💡 Hint

Remember that range(1, 5) includes numbers from 1 up to but not including 5.

The range(1, 6) generates numbers 1, 2, 3, 4, 5. Their sum is 15, so the output is 15.

🧠 Conceptual

intermediate

Identify the cause of a runtime error

What is the most likely cause of the following error message when running this code?

IndexError: list index out of range

Code snippet:

numbers = [10, 20, 30]
print(numbers[3])

Intro to Computing

numbers = [10, 20, 30]
print(numbers[3])

A Trying to access an element beyond the list length

B Using a wrong variable name

C Syntax error in the code

D Dividing by zero

💡 Hint

Check the list length and the index used.

The list has 3 elements indexed 0, 1, 2. Accessing index 3 is out of range, causing the error.

❓ Comparison

advanced

Compare debugging approaches for a logic error

Which debugging approach is best to find why a program calculating average scores gives wrong results?

A Add print statements to check intermediate values during calculation

B Rewrite the entire program from scratch

C Ignore the problem and run the program again

D Change variable names randomly to see if it fixes the issue

💡 Hint

Think about how to find where the calculation goes wrong step-by-step.

Adding print statements helps observe values during execution to locate the logic error.

❓ identification

advanced

Identify the type of bug from a code snippet

What type of bug is present in the following code?

def divide(a, b):
    return a / b

result = divide(10, 0)
print(result)

Intro to Computing

def divide(a, b):
    return a / b

result = divide(10, 0)
print(result)

A Typo in function name causing failure

B Syntax error because of missing colon

C Logic error producing wrong output

D Runtime error due to division by zero

💡 Hint

What happens when dividing by zero in Python?

Dividing by zero causes a runtime error called ZeroDivisionError.

🚀 Application

expert

Debugging a complex scenario with multiple errors

Given the following code, what will be the output or error?

def process(data):
    total = 0
    for i in range(len(data)):
        total += data[i]
    return total // len(data)

values = [10, 20, '30', 40]
print(process(values))

Intro to Computing

def process(data):
    total = 0
    for i in range(len(data)):
        total += data[i]
    return total // len(data)

values = [10, 20, '30', 40]
print(process(values))

A SyntaxError due to wrong operator

B 100

C TypeError because of adding integer and string

D ZeroDivisionError because of division by zero

💡 Hint

Check the data types inside the list and how addition works.

Adding an integer and a string causes a TypeError at runtime.