Randomized quicksort

#1

In the quicksort lecture I have been taught to take middle item as pivot, I am confused about randomized quicksort.

import java.util.*;
public class Main
{
static void quick(long []a,int low,int high)
{
int left=0,right=a.length-1,pivot=(low+high)/2;

    if (low>=high)
    {
        return;
    }
    while(left<=right)
    {
        while(a[left]<a[pivot])
        left++;
        
        while(a[right]>a[pivot])
        right--;
        
        if(left<=right)
        {
            long temp=a[left];
            a[left]=a[right];
            a[right]=temp;
            left++; 
            right--;
        }
    }
    quick(a,low,right);
    quick(a,left,high);
}
public static void main(String[] args) 
{
    Scanner sc=new Scanner(System.in);
    int size=sc.nextInt();
    long arr[]=new long[size];
    for(int i=0;i<size;i++)
    arr[i]=sc.nextInt();
	quick(arr,0,arr.length-1);
	for(long i:arr)
	{
	    System.out.print(i+" ");
	}
}

}

I tried this…it has gone through only 1 test case

#2

@tishachhabra2702_8fc5a68a2e295e35 in randomized quick sort you have to take a pivot at a random index and that random number can be generated using Random Class of java Like shown in below link :

#3

import java.lang.Math; import java.util.; public class Main { static void quick(long []a,int low,int high) { Random r=new Random(); int left=0,right=a.length-1,pivot=(int)Math.random()(high-low+1)+low; if (low>=high) { return; } while(left<=right) { while(a[left]<a[pivot]) left++; while(a[right]>a[pivot]) right–; if(left<=right) { long temp=a[left]; a[left]=a[right]; a[right]=temp; left++; right–; } } quick(a,low,right); quick(a,left,high); } public static void main(String[] args) { Scanner sc=new Scanner(System.in); int size=sc.nextInt(); long arr[]=new long[size]; for(int i=0;i<size;i++) arr[i]=sc.nextInt(); quick(arr,0,arr.length-1); for(long i:arr) { System.out.print(i+" "); } } }

#4

This is also not working

#5

@tishachhabra2702_8fc5a68a2e295e35 Can you send the code in readable form? Try adding triple ‘’’ before and after the code to specify to the editor that it is a code or Try using your laptop to send the code.

#6

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