C Implementation

public class CountingSort
{
    public static void SortCounting(int[] input, int min, int max)
    {
        var count = new int[max - min + 1];
        var z = 0;

        for (var i = 0; i < count.Length; i++)
            count[i] = 0;

        foreach (int i in input)
            count[i - min]++;

        for (var i = min; i <= max; i++)
        {
            while (count[i - min]-- > 0)
            {
                input[z] = i;
                ++z;
            }
        }
    }

    public static int[] Main(int[] input)
    {
        SortCounting(input, input.Min(), input.Max());
        return input;
    }
}