2a.txt

import java.util.Random;
import java.util.Scanner;
public class quicksort
{
 static int max=30000;
 public static void main(String[] args)
 {
int a[]=new int[max];
 long start,end;
 Scanner sobj=new Scanner (System.in);
System.out.println("********QUICK SORT ALGORITHM********");
System.out.println("Enter the no. of elements to be sorted :");
int n=sobj.nextInt();
Random rand=new Random();
for(int i=0;i<n;i++)
{
a[i]=rand.nextInt(100);
}
System.out.println("Array elements to be sorted are :");
for(int i=0;i<n;i++)
{
System.out.print(a[i]+" ");
}
a[n]=9999;
start=System.nanoTime();
qsort(a,0,n-1);
end=System.nanoTime();
System.out.println("\nThe sorted elements are :");
for(int i=0;i<n;i++)
{
System.out.print(a[i]+" ");
}
System.out.println("\nThe time taken to sort is "+(end-start)+"ns");
System.out.println("******************************************");
}//end of main
static void qsort(int a[],int low,int high)
{
int s;
if(low<high)
{
s=partition(a,low,high);//s is the final position of pivot element in 
a[low:high]
qsort(a,low,s-1);
qsort(a,s+1,high);
}
}
static int partition(int a[],int low,int high)
{
int pivot,i,j;
pivot=a[low];
i=low;
j=high;
while(i<=j)
{
while(a[i]<=pivot) 
 i++;
while(a[j]>pivot) 
 j--;
if(i<j)
swap(a,i,j);
}
a[low]=a[j];
a[j]=pivot; 
return j;
}
static void swap(int a[],int i,int j)
{
int temp;
temp=a[i];
a[i]=a[j];
a[j]=temp;
}
}