Selection Sort Algorithm in DSA C++ - Build from Scratch

Selection Sort Algorithm

📖 Scenario: You are helping a librarian organize a small shelf of books by their ID numbers. The librarian wants the books sorted from smallest to largest ID so they are easy to find.

🎯 Goal: Build a program that sorts a list of book IDs using the selection sort algorithm. You will create the list, set up a variable to track the smallest value, implement the sorting logic, and finally print the sorted list.

📋 What You'll Learn

Create a list of integers called book_ids with the exact values: 45, 12, 78, 34, 23

Create an integer variable called min_index to track the position of the smallest value

Use nested for loops with variables i and j to implement selection sort

Swap elements in book_ids to sort the list in ascending order

Print the sorted book_ids list in the format: 12 -> 23 -> 34 -> 45 -> 78 -> null

💡 Why This Matters

🌍 Real World

Sorting is a common task in organizing data, like arranging books, files, or records in order.

💼 Career

Understanding sorting algorithms like selection sort helps in software development, data analysis, and optimizing programs.

1

Create the list of book IDs

Create a list of integers called book_ids with these exact values: 45, 12, 78, 34, 23

DSA C++

# Create the list book_ids with the given values
# Your code here

Hint

Use std::vector<int> to create the list and initialize it with the given numbers.

2

Create the variable to track the smallest value index

Create an integer variable called min_index to track the position of the smallest value during sorting

DSA C++

std::vector book_ids = {45, 12, 78, 34, 23};
// Create the variable min_index
# Your code here

Hint

Declare min_index as an integer without initializing it yet.

3

Implement the selection sort logic

Use nested for loops with variables i and j to implement selection sort on book_ids. Inside the outer loop, set min_index = i. Inside the inner loop, update min_index if a smaller value is found. After the inner loop, swap book_ids[i] and book_ids[min_index] if needed.

DSA C++

std::vector book_ids = {45, 12, 78, 34, 23};
int min_index;
// Implement selection sort using for loops
# Your code here

Hint

Use two loops: the outer loop picks the current position, the inner loop finds the smallest value's index. Swap after inner loop ends.

4

Print the sorted list

Print the sorted book_ids list in the format: 12 -> 23 -> 34 -> 45 -> 78 -> null. Use a for loop to print each element followed by ->, and print null at the end.

DSA C++

std::vector book_ids = {45, 12, 78, 34, 23};
int min_index;
for (int i = 0; i < (int)book_ids.size() - 1; i++) {
    min_index = i;
    for (int j = i + 1; j < (int)book_ids.size(); j++) {
        if (book_ids[j] < book_ids[min_index]) {
            min_index = j;
        }
    }
    if (min_index != i) {
        int temp = book_ids[i];
        book_ids[i] = book_ids[min_index];
        book_ids[min_index] = temp;
    }
}
// Print the sorted list
# Your code here

Hint

Use a loop to print each number followed by ->, then print null after the loop.