QuickSort

//Rextester.Program.Main is the entry point for your code. Don't change it.
//Compiler version 4.0.30319.17929 for Microsoft (R) .NET Framework 4.5

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace Rextester
{
    public class Program
    {
        private static void quick( int[] v, int inicio, int fim )
        {
        int aux, down, up, pivo;
        pivo = v[ inicio ];
        down = inicio;
        up   = fim;
        while( down < up ){

            while( v[ down ] <= pivo && down < fim ) {
             down++;
            }

            while( v[ up ] > pivo    && up > inicio ) {
             up--;
            }

            if( down < up ){
                 aux       = v[ down ];
                 v[ down ] = v[ up ];
                 v[ up ]   = aux;
            }
        }
        v[ inicio ] = v[ up ];
        v[ up ] = pivo;
            if( inicio < up && inicio != up-1 ) {
                quick( v , inicio , up-1 );
            }
            if( fim > down && up+1 != fim ) {
                quick( v , up+1 , fim );
            }
        }


        public static void Main(string[] args)
        {
            Console.WriteLine("Início!");
            int[] vetor = new int[]{42,34,56,18,71,23,25,66,87};

            Console.WriteLine("\nVetor inicial:\n");
            for (int r = 0; r < vetor.Length; r++)
            {
                Console.Write("{0}  ", vetor[r]);
            }

            quick( vetor , 0 , vetor.Length-1 );

            Console.WriteLine("\nVetor final:\n");
            for (int r = 0; r < vetor.Length; r++)
            {
                Console.Write("{0}  ", vetor[r]);
            }


        }
    }
}