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Quicksort.cs
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Quicksort.cs
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using System;
public class Quicksort
{
public static void Swap(int[] arr, int i, int j)
{
var temp = arr[i];
arr[i] = arr[j];
arr[j] = temp;
}
public static void Qsort(int[] arr, int left, int right)
{
var pivot = arr[(left + right) >> 1];
var i = left;
var j = right;
while (i <= j)
{
while (arr[i] < pivot)
i++;
while (arr[j] > pivot)
j--;
if (i <= j)
{
Swap(arr, i++, j--);
}
}
if (left < j)
{
Qsort(arr, left, j);
}
if (i < right)
{
Qsort(arr, i, right);
}
}
public static double Sort(int len)
{
var arr = new int[len];
var random = new Random();
for (var i = 0; i < arr.Length; i++)
{
arr[i] = (int)(random.Next(len));
if (i % 2 == 0)
{
arr[i] = -arr[i];
}
}
var start = DateTime.Now;
Qsort(arr, 0, arr.Length - 1);
var diff = DateTime.Now - start;
for (var i = 1 ; i < arr.Length ; i++)
{
if (arr[i-1] > arr[i])
{
Console.WriteLine("not sorted!!");
Environment.Exit(1);
}
}
return diff.TotalMilliseconds;
}
public static void Main(string[] args)
{
if (args.Length != 1)
{
Console.WriteLine("usage: Quicksort ARRAYLENGTH");
Environment.Exit(1);
}
var len = int.Parse(args[0]);
var time = double.MaxValue;
for (var i = 0 ; i < 5 ; i++)
{
time = Math.Min(time, Sort(len));
}
Console.WriteLine("C# quicksort: " + time + " ms (" + len + ")");
}
}