Question

Can I get help with implementing a quick sort in my program?

Starter Code:

import java.util.Random;
import java.util.Scanner;
import java.util.Arrays;

import java.util.Collections;
import java.util.ArrayList;
public class RQS {
public static int[] prepareData(int[] patients){
/*
Data is prepared by inserting random values
between 1 and 1000. Data items may be assumed to
be unique.
Please refer to lab spec for the problem definiton.
*/
// what is our range?
int max = 1000;
// create instance of Random class
Random randomNum = new Random();

ArrayList<Integer> list = new ArrayList<Integer>();
for (int i=0; i<patients.length; i++) {
int ids = randomNum.nextInt(max);
list.add(ids);
}
Collections.shuffle(list);

for (int i=0; i<patients.length; i++) {
patients[i] = list.get(i);
}

return patients;
}
public static int[] sortArray(int[] patient_ids){
/*
Add your logic below to sort the array.*/

return patient_ids;
}

public static void main(String[] args) {
System.out.println("Enter the no of patients:");
Scanner scan = new Scanner(System.in);
int patients = scan.nextInt();
int[] patient_ids = new int[patients];
int[] patients_populated = prepareData(patient_ids);

/* The line below will print the output.
Do not uncomment this lines. */
System.out.println("Unsorted:\t" + Arrays.toString(patients_populated));

/* Implement the sortArray method, so as to
get the correct results.*/
int[] sorted_array = sortArray(patients_populated);

/* The line below will print the output.
Do not uncomment this lines. */
System.out.println("Sorted:\t" + Arrays.toString(sorted_array));

}
}

The output of the program should be generated using the ascending order format. Make necessary code modifications to this starter-code file. Read through the comments in the code file for additional information on the structure of the code. I could really use some help with this will give a thumbs up for anybody that can help.

Answer 1

import java.util.Random;
import java.util.Scanner;
import java.util.Arrays;

import java.util.Collections;
import java.util.ArrayList;
public class RQS {
public static int[] prepareData(int[] patients){
/*
Data is prepared by inserting random values
between 1 and 1000. Data items may be assumed to
be unique.
Please refer to lab spec for the problem definiton.
*/
// what is our range?
int max = 1000;
// create instance of Random class
Random randomNum = new Random();

ArrayList<Integer> list = new ArrayList<Integer>();
for (int i=0; i<patients.length; i++) {
int ids = randomNum.nextInt(max);
list.add(ids);
}
Collections.shuffle(list);

for (int i=0; i<patients.length; i++) {
patients[i] = list.get(i);
}

return patients;
}
public static int[] sortArray(int[] patient_ids){
/*
Add your logic below to sort the array.*/
   qsort(patient_ids,0,patient_ids.length-1);
return patient_ids;
}

private static void qsort(int [] ar,int l,int r){
   int i=l,j=r;
   int x=0,y=0;
  
   // store middle element in x
   x=ar[(l+r)/2];
   do{
       // get position of x within array
       while(ar[i]<x && i<r){i++;}
       while(x<ar[j] && j>l ){j--;}
          
       // replace i and j
       if(i<=j){
           y=ar[i];
           ar[i]=ar[j];
           ar[j]=y;
           i++;
           j--;
       }      
   }while(i<=j);
  
   // sort within l and j
   if(l<j) qsort(ar,l,j);
  
   // sort within i and r
   if(i<r) qsort(ar,i,r);
}

public static void main(String[] args) {
System.out.println("Enter the no of patients:");
Scanner scan = new Scanner(System.in);
int patients = scan.nextInt();
int[] patient_ids = new int[patients];
int[] patients_populated = prepareData(patient_ids);

/* The line below will print the output.
Do not uncomment this lines. */
System.out.println("Unsorted:\t" + Arrays.toString(patients_populated));

/* Implement the sortArray method, so as to
get the correct results.*/
int[] sorted_array = sortArray(patients_populated);

/* The line below will print the output.
Do not uncomment this lines. */
System.out.println("Sorted:\t" + Arrays.toString(sorted_array));

}
}