Set membership testing in Python - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of set membership test with strings

What is the output of this Python code?

Python

fruits = {'apple', 'banana', 'cherry'}
print('banana' in fruits)
print('orange' in fruits)

A False\nTrue

B True\nTrue

C True\nFalse

D False\nFalse

💡 Hint

Check if each fruit is inside the set using the 'in' keyword.

The set contains 'banana' but not 'orange', so 'banana' in fruits is True and 'orange' in fruits is False.

❓ Predict Output

intermediate

Set membership with numbers and types

What will this code print?

Python

numbers = {1, 2, 3, 4}
print(3 in numbers)
print('3' in numbers)

A True\nTrue

B False\nFalse

C False\nTrue

D True\nFalse

💡 Hint

Remember that 3 (int) and '3' (string) are different types.

3 is in the set, but the string '3' is not, so the first print is True and the second is False.

❓ Predict Output

advanced

Set membership with mutable elements

What error does this code raise?

Python

my_set = {1, 2, [3, 4]}
print(2 in my_set)

A TypeError

B SyntaxError

C KeyError

D No error, prints True

💡 Hint

Sets cannot contain mutable elements like lists.

Lists are mutable and cannot be added to a set, so Python raises a TypeError.

❓ Predict Output

advanced

Set membership with nested tuples

What is the output of this code?

Python

nested_set = {(1, 2), (3, 4)}
print((1, 2) in nested_set)
print((2, 1) in nested_set)

A False\nTrue

B True\nFalse

C True\nTrue

D False\nFalse

💡 Hint

Tuples are ordered, so (1, 2) is different from (2, 1).

The tuple (1, 2) is in the set, but (2, 1) is not, so the output is True then False.

🧠 Conceptual

expert

Why does 'in' membership test run faster on sets?

Why is checking membership with 'in' faster on a set than on a list?

A Sets use hashing to check membership in constant time, while lists check each item one by one.

B Sets store elements in sorted order, so membership uses binary search.

C Sets convert elements to strings before checking membership, making it faster.

D Sets use multiple threads internally to check membership faster.

💡 Hint

Think about how sets organize data internally compared to lists.

Sets use a hash table which allows them to find elements quickly without checking every item, unlike lists which check each element in order.