Quick Sort algorithm. This will handle arrays that are already sorted, and arrays with duplicate keys. - CSharp System

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Description

Quick Sort algorithm. This will handle arrays that are already sorted, and arrays with duplicate keys.

Demo Code


using System.Collections;
using System.Text;
using System;/*from   www  .  j  a v a  2  s. c  om*/

public class Main{
        /// <summary>
        /// This is a generic version of C.A.R Hoare's Quick Sort 
        /// algorithm.  This will handle arrays that are already
        /// sorted, and arrays with duplicate keys.
        /// </summary>
        /// <remarks>
        /// If you think of a one dimensional array as going from
        /// the lowest index on the left to the highest index on the right
        /// then the parameters to this function are lowest index or
        /// left and highest index or right.  The first time you call
        /// this function it will be with the parameters 0, a.length - 1.
        /// </remarks>
        /// <param name="array">Array of string to be sorted.</param>
        /// <param name="l">Left boundary of array partition</param>
        /// <param name="r">Right boundary of array partition</param>
        private static void Sort(string[] array, int l, int r)
        {
            int M = 4;
            int i;
            int j;
            string v;

            if ((r - l) <= M)
            {
                InsertionSort(array, l, r);
            }
            else
            {
                i = (r + l) / 2;

                if (string.Compare(array[l], array[i]) > 0)
                    Swap(array, l, i);

                if (string.Compare(array[l], array[r]) > 0)
                    Swap(array, l, r);

                if (string.Compare(array[i], array[r]) > 0)
                    Swap(array, i, r);

                j = r - 1;
                Swap(array, i, j);

                i = l;
                v = array[j];
                for (; ; )
                {
                    while (string.Compare(array[++i], v) < 0)
                    { }

                    while (string.Compare(array[--j], v) > 0)
                    { }

                    if (j < i)
                        break;
                    Swap(array, i, j);

                }
                Swap(array, i, r - 1);

                Sort(array, l, j);
                Sort(array, i + 1, r);
            }
        }
        #endregion Replace method

        #region Sort Method

        /// <summary>
        /// Sorts an array of strings.
        /// </summary>
        /// <remarks>
        /// Original code by user "Jay Jay"
        /// http://www.tinyclr.com/codeshare/entry/475
        /// Modified to be specifically suites to sorting arrays of strings.    
        /// </remarks>
        /// <param name="array">Array of string to be sorted.</param>
        public static void Sort(string[] array)
        {
            Sort(array, 0, array.Length - 1);
        }
}

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