Sorting algorithms (bubble, selection) in Intro to Computing - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ trace

intermediate

Trace the Bubble Sort Process

Given the list [5, 3, 8, 4], what is the list after the first full pass of bubble sort?

Intro to Computing

lst = [5, 3, 8, 4]
for i in range(len(lst)-1):
    if lst[i] > lst[i+1]:
        lst[i], lst[i+1] = lst[i+1], lst[i]

A [3, 5, 4, 8]

B [3, 4, 5, 8]

C [5, 3, 4, 8]

D [3, 5, 8, 4]

💡 Hint

Bubble sort compares adjacent pairs and swaps if the left is bigger.

After the first pass, the largest number moves to the end. The swaps are: 5 and 3 swap → [3,5,8,4], then 5 and 8 no swap, then 8 and 4 swap → [3,5,4,8].

🧠 Conceptual

intermediate

Selection Sort Key Idea

Which statement best describes the main idea of selection sort?

A Repeatedly find the smallest unsorted element and move it to the front.

B Repeatedly swap adjacent elements if they are in the wrong order.

C Use a pivot to partition the list into smaller and larger elements.

D Divide the list into halves and sort each half recursively.

💡 Hint

Think about how selection sort picks elements to place in order.

Selection sort finds the smallest element in the unsorted part and swaps it with the first unsorted element, moving the boundary forward.

❓ Comparison

advanced

Compare Bubble Sort and Selection Sort Behavior

Which of the following is true about bubble sort compared to selection sort?

A Selection sort swaps elements more frequently than bubble sort.

B Bubble sort swaps elements more frequently than selection sort.

C Both algorithms swap elements the same number of times.

D Bubble sort never swaps elements.

💡 Hint

Consider how each algorithm moves elements during sorting.

Bubble sort swaps adjacent elements whenever they are out of order, often many times per pass. Selection sort only swaps once per pass when placing the smallest element.

🔍 Analysis

advanced

Output of Selection Sort Partial Pass

What is the list after the first pass of selection sort on [7, 2, 5, 3]?

Intro to Computing

lst = [7, 2, 5, 3]
min_index = 0
for j in range(1, len(lst)):
    if lst[j] < lst[min_index]:
        min_index = j
lst[0], lst[min_index] = lst[min_index], lst[0]

A [3, 2, 5, 7]

B [7, 2, 5, 3]

C [2, 7, 5, 3]

D [2, 3, 5, 7]

💡 Hint

Selection sort finds the smallest element and swaps it with the first element.

The smallest element is 2 at index 1. It swaps with element at index 0 (7), resulting in [2, 7, 5, 3].

❓ identification

expert

Identify the Algorithm from Behavior

A sorting algorithm repeatedly swaps adjacent elements if they are out of order, and after each full pass, the largest unsorted element moves to its correct position at the end. Which algorithm is this?

A Selection sort

B Merge sort

C Insertion sort

D Bubble sort

💡 Hint

Think about which algorithm moves the largest element to the end each pass by swapping neighbors.

Bubble sort works by swapping adjacent elements and pushing the largest unsorted element to the end after each pass.