using System;

​

public class Program

{

    public static void Main()

    {

        int[] numbers = new int[]{12, 9, 7, 15, 10, 20, 19, 8, 4, 3, 2, 2, 1, 1};

        QuickSort(numbers);

        foreach (int i in numbers)

        {

            Console.WriteLine("Number: {0}", i);

        }

    }

​

    public static void QuickSort(int[] numbers)

    {

        QuickSort(numbers, 0, numbers.Length - 1);

    }

​

    private static void QuickSort(int[] numbers, int start, int end)

    {

        if (start < end)

        {

            int pivot = Partition(numbers, start, end);

            QuickSort(numbers, start, pivot - 1);

            QuickSort(numbers, pivot + 1, end);

        }

    }

​

    private static int Partition(int[] numbers, int start, int end)

    {

        int pivot = numbers[end];

        int i = start;

        for (int j = start; j < end; j++)

        {

            if (numbers[j] <= pivot)

            {

                int temp = numbers[i];

                numbers[i] = numbers[j];

                numbers[j] = temp;

                i = i + 1;

            }

        }

​

        int temp2 = numbers[i];

        numbers[i] = numbers[end];

        numbers[end] = temp2;

        return i;

    }

}