# Selection sort

Selection sort – an array sorting algorithm that is comparable in speed with bubble sorting.

## Description of the selection sorting algorithm

The selection sorting algorithm consists of the following steps:

• First, determine the position of the minimum element of the array;
• We make an exchange of the minimum element with the element at the beginning of the array. It turns out that the first element of the array is already sorted;
• Reduce the working area of ​​the array, discarding the first element, and for the subarray that happened, repeat the sorting.

## Implementing sort by selection

``````using System;
class program
{
// method for finding the position of the minimum element of a subarray, starting at position n
static int IndexOfMin(int[] array, int n)
{
int result = n;
for (var i = n; i < array.Length; ++i)
{
if (array[i] < array[result])
{
result = i;
}
}

return result;
}

// method for exchanging elements
static void Swap(ref int x, ref int y)
{
var t = x;
x = y;
y = t;
}

// selection sort
static int[] SelectionSort(int[] array, int currentIndex = 0)
{
if (currentIndex == array.Length)
return array;

var index = IndexOfMin(array, currentIndex);
if (index != currentIndex)
{
Swap(ref array[index], ref array[currentIndex]);
}

return SelectionSort(array, currentIndex + 1);
}

static void Main(string[] args)
{
Console.WriteLine("Sort by selection");
Console.Write("Enter elements of the array:");
var s = Console.ReadLine().Split(new[] { "", ",", ";" }, StringSplitOptions.RemoveEmptyEntries);
var a = new int[s.Length];
for (int i = 0; i < s.Length; i++)
{
a[i] = Convert.ToInt32(s[i]);
}

Console.WriteLine("Ordered array: {0}", string.Join(",", SelectionSort(a)));