Selection Sort

1. Overview

The selection sort algorithm sorts an array by repeatedly finding the minimum element (considering ascending order) from the unsorted part and putting it at the beginning. It's one of the Greedy Algorithms.

2. Description

2.1 Procedure

The algorithm maintains two subarrays in a given array. In every iteration of selection sort, the minimum element (considering ascending order) from the unsorted subarray is picked and moved to the sorted subarray.

• The subarray is already sorted.
• Remaining subarray which is unsorted.

arr[] = 64 25 12 22 11

// Find the minimum element in arr[0...4]
// and place it at beginning
11 25 12 22 64

// Find the minimum element in arr[1...4]
// and place it at beginning of arr[1...4]
11 12 25 22 64

// Find the minimum element in arr[2...4]
// and place it at beginning of arr[2...4]
11 12 22 25 64

// Find the minimum element in arr[3...4]
// and place it at beginning of arr[3...4]
11 12 22 25 64 

2.2 Time and Space Complexity

Particular	Complexity
Worst-case performance	O($n^{2}$) comparisons, O(n) swaps
Best-case performance	O($n^{2}$) comparisons, O(n) swaps
Average performance	O($n^{2}$) comparisons, O(n) swaps
Worst-case space complexity	O(1) auxiliary

3. Reference

https://en.wikipedia.org/wiki/Selection_sort

https://www.geeksforgeeks.org/selection-sort/

https://www.youtube.com/watch?v=xWBP4lzkoyM