Arrays and lists in Intro to Computing - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ trace

intermediate

Trace the final list after operations

Given the following steps on a list, what is the final list?

my_list = [1, 2, 3, 4]
my_list.append(5)
my_list.pop(1)
my_list.insert(2, 10)

Intro to Computing

my_list = [1, 2, 3, 4]
my_list.append(5)
my_list.pop(1)
my_list.insert(2, 10)

A [1, 2, 10, 3, 4, 5]

B [1, 10, 3, 4, 5]

C [1, 3, 4, 10, 5]

D [1, 3, 10, 4, 5]

💡 Hint

Remember that pop removes the item at the given index and append adds to the end.

Starting list: [1, 2, 3, 4]. After append(5): [1, 2, 3, 4, 5]. pop(1) removes element at index 1 (which is 2), so list becomes [1, 3, 4, 5]. insert(2, 10) adds 10 at index 2, resulting in [1, 3, 10, 4, 5].

🧠 Conceptual

intermediate

Understanding list indexing and slicing

What will be the output of the following slicing operation?

numbers = [10, 20, 30, 40, 50, 60]
print(numbers[1:5:2])

Intro to Computing

numbers = [10, 20, 30, 40, 50, 60]
print(numbers[1:5:2])

A [20, 30, 40, 50]

B [20, 40]

C [20, 40, 60]

D [10, 30, 50]

💡 Hint

Slicing syntax is list[start:stop:step]. It includes start index but excludes stop index.

numbers[1:5:2] means start at index 1 (20), go up to but not including index 5 (which is 60), stepping by 2. So elements at index 1 and 3 are selected: 20 and 40.

❓ Comparison

advanced

Compare list and array behavior

Which statement correctly describes a key difference between arrays and lists in programming?

A Arrays can only store elements of the same type, while lists can store elements of different types.

B Lists require fixed size at creation, arrays can grow dynamically.

C Arrays support appending elements at any position, lists do not.

D Lists are stored in contiguous memory locations, arrays are not.

💡 Hint

Think about type restrictions and flexibility of these data structures.

Arrays typically store elements of the same type for efficient memory use. Lists are more flexible and can hold different types of elements.

❓ identification

advanced

Identify the error in list operation

What error will this code produce?

my_list = [1, 2, 3]
print(my_list[5])

Intro to Computing

my_list = [1, 2, 3]
print(my_list[5])

A IndexError: list index out of range

B TypeError: list indices must be integers

C ValueError: invalid index

D SyntaxError: invalid syntax

💡 Hint

Check if the index 5 exists in the list of length 3.

The list has indices 0, 1, and 2. Accessing index 5 is out of range, causing an IndexError.

🚀 Application

expert

Determine the number of elements after nested list flattening

Given the nested list below, how many elements will the flattened list contain?

nested = [[1, 2], [3, 4, 5], [6], []]

Assuming flattening means combining all inner elements into one list.

Intro to Computing

nested = [[1, 2], [3, 4, 5], [6], []]

A 7

B 5

C 6

D 8

💡 Hint

Count all elements inside each inner list and sum them.

Inner lists have lengths 2, 3, 1, and 0 respectively. Total elements = 2 + 3 + 1 + 0 = 6.