SelectionSorter.cs

using System.Collections.Generic;
using Algorithms.Common;

namespace Algorithms.Sorting
{
    public static class SelectionSorter
    {
        public static void SelectionSort<T>(this IList<T> collection, Comparer<T> comparer = null)
        {
            comparer = comparer ?? Comparer<T>.Default;
            collection.SelectionSortAscending(comparer);
        }

        /// <summary>
        /// Public API: Sorts ascending
        /// </summary>
        public static void SelectionSortAscending<T>(this IList<T> collection, Comparer<T> comparer)
        {
            int i;
            for(i=0;i<collection.Count;i++){
                int min=i;
                for (int j = i + 1; j < collection.Count; j++) { 
                    if (comparer.Compare(collection[j], collection[min])<0) 
                        min=j;
                }
                collection.Swap(i,min);
            }
        }

        /// <summary>
        /// Public API: Sorts ascending
        /// </summary>
        public static void SelectionSortDescending<T>(this IList<T> collection, Comparer<T> comparer)
        {
            int i;
            for (i = collection.Count-1; i >0; i--)
            {
                int max = i;
                for (int j = 0; j <=i; j++)
                {
                    if (comparer.Compare(collection[j], collection[max]) < 0)
                        max = j;
                }
                collection.Swap(i, max);
            }
        }
    }
}