Quick Sort

// Write a program that sorts an array of strings using the quick sort algorithm (find it in Wikipedia).

using System;

class QuickSort
{
    static void Main(string[] args)
    {
        // Create an unsorted array of string elements
        string[] unsorted = { "z", "e", "x", "c", "m", "q", "a"};

        // Print the unsorted array
        for (int i = 0; i < unsorted.Length; i++)
        {
            Console.Write(unsorted[i] + " ");
        }

        Console.WriteLine();

        // Sort the array
        Quicksort(unsorted, 0, unsorted.Length - 1);

        // Print the sorted array
        for (int i = 0; i < unsorted.Length; i++)
        {
            Console.Write(unsorted[i] + " ");
        }

        Console.WriteLine();
    }

    public static void Quicksort(string[] elements, int left, int right)
    {
        int i = left, j = right;
        string middle = elements[(left + right) / 2];

        // if you want to see whole process
        //for (int k = 0; k < elements.Length; k++)
        //{
        //    Console.Write(elements[k] + " ");
        //}
        //Console.Write("\"{0}\"", middle);
        //Console.WriteLine();

        while (i <= j)
        {
            while (elements[i].CompareTo(middle) < 0)
            {
                i++;
            }

            while (elements[j].CompareTo(middle) > 0)
            {
                j--;
            }

            if (i <= j)
            {
                // Swap
                string tmp = elements[i];
                elements[i] = elements[j];
                elements[j] = tmp;

                i++;
                j--;
            }
        }

        // Recursive calls
        if (left < j)
        {
            Quicksort(elements, left, j);
        }

        if (i < right)
        {
            Quicksort(elements, i, right);
        }
    }
}