Question

Be sure to include the number of total swaps in each sort.

Create a total_Time variable is the total time it takes all 1000 iterations to run. DO NOT INCLUE THE TIME IT TAKES TO GENERATE A UNIQUE RANDOM ARRAY EACH LOOP.

In java, Write a computer program that prompts the user for one number, n for the number of items in the array to sort and create and sort 1000 different arrays of this size,  timing the run to get an average time to sort an array of this size. Then do the following:

Initiate a variable running_time to 0

Create a for loop that iterates 1000 times.

In the body of the loop,

Create an array of n random integers (Make sure you make the range of the random numbers substantially bigger than the array, ie. if the array size is 500 have the random number generator pick numbers between 1 and 5000. For the largest array have the random number generator pick numbers between 1 and 50,000).

Get the time and set this to start-time (notice the sort is started after each array is built. You want to time the srt process only). You will have to figure out what the appropriate command is in the programming language you are using to find the time (Important: Do not start the timer until after the array is created).

Use bubble sort to sort the array

Get the time and set this to end-time Subtract start-time from end-time and add the result to total_time

Once the program has run, NOTE THE FOLLOWING:

The number of items sorted

The average running time for each array (total_time/1000)

Repeat the process using 500, 2500 and 5000 as the size of the array.

Create a NEW class and repeat the process for selection sort

Answer 1

BubbleSort.java

import java.util.Scanner;
import java.util.Random;
public class BubbleSort
{
   //Implementation of bubbleSort and it'll return the number of swaps
   public static int bubbleSort(int[] arr)
   {
       int swap=0;
       for(int i=0;i<arr.length-1;i++)
       {
           for(int j=0;j<arr.length-1-i;j++)
           {
               if(arr[j]>arr[j+1])
               {
                   swap++;
                   int temp=arr[j];
                   arr[j]=arr[j+1];
                   arr[j+1]=temp;
               }
           }
       }
       return swap;
   }
   public static void main(String[] args)
   {
       //Object creation for scanner class
       Scanner scanner=new Scanner(System.in);
       System.out.print("Enter number n: ");
       //User input for n  
       int n = scanner.nextInt();
       //object creation for random class
       Random rand=new Random();
       //range should be higher than n
       int range=n*10;
       //Initialize total_time to 0
       long total_time=0;

       //sort for 1000 diiferent arrays of size n
       for(int i=0;i<1000;i++)
       {
           int[] arr=new int[n];
           for(int j=0;j<n;j++)
           {
               arr[j] = rand.nextInt(range);
           }
           long start_time=System.currentTimeMillis();
           bubbleSort(arr);
           long end_time=System.currentTimeMillis();
           total_time+=(end_time-start_time);
       }
       //output printing
       System.out.println("\nNumber of items sorted: "+n);
       System.out.println("\nThe average running time for each array: "+total_time/1000.0+" milli seconds");
   }
}

output screenshot:

C:\Users\srini\Desktop>javac BubbleSort.java C:\Users\srini\Desktop>java BubbleSort Enter number n: 100 Number of items sorted: 100 The average running time for each array: 0.051 milli seconds C:\Users\srini\Desktop>java BubbleSort Enter number n: 500 Number of items sorted: 500 The average running time for each array: 0.432 milli seconds C:\Users\srini\Desktop>java BubbleSort Enter number n: 2500 Number of items sorted: 2500 The average running time for each array: 6.605 milli seconds C:\Users\srini\Desktop>java BubbleSort Enter number n: 5000 Number of items sorted: 5000 The average running time for each array: 35.94 milli seconds C:\Users\srini\Desktop>

SelectionSort.java

import java.util.Scanner;
import java.util.Random;
public class SelectionSort
{
   //Implementation of selectionSort and it'll return the number of swaps
   public static int selectionSort(int[] arr)
   {
       int swap=0;
       for(int i=0;i<arr.length-1;i++)
       {
           int min=i;
           for(int j=i+1;j<arr.length;j++)
           {
               if(arr[j]<arr[min])
               {
                   min=j;
               }
           }
           if(min!=i)
           {
               swap++;
               int temp=arr[min];
               arr[min]=arr[i];
               arr[i]=temp;
           }
       }
       return swap;
   }
   public static void main(String[] args)
   {
       Scanner scanner=new Scanner(System.in);
       System.out.print("Enter number n: ");  
       int n = scanner.nextInt();
       Random rand=new Random();
       int range=n*10;
       long total_time=0;

       for(int i=0;i<1000;i++)
       {
           int[] arr=new int[n];
           for(int j=0;j<n;j++)
           {
               arr[j] = rand.nextInt(range);
           }
           long start_time=System.currentTimeMillis();
           selectionSort(arr);
           long end_time=System.currentTimeMillis();
           total_time+=(end_time-start_time);
       }
       System.out.println("\nNumber of items sorted: "+n);
       System.out.println("\nThe average running time for each array: "+total_time/1000.0+" milli seconds");
   }
}

output screenshot:

C:\Users\srini\Desktop>javac SelectionSort.java C:\Users\srini\Desktop>java SelectionSort Enter number n: 100 Number of items sorted: 100 The average running time for each array: 0.022 milli seconds C:\Users\srini\Desktop>java SelectionSort Enter number n: 500 Number of items sorted: 500 The average running time for each array: 0.219 milli seconds C:\Users\srini\Desktop>java SelectionSort Enter number n: 2500 Number of items sorted: 2500 The average running time for each array: 2.741 milli seconds C:\Users\srini\Desktop>java SelectionSort Enter number n: 5000 Number of items sorted: 5000 The average running time for each array: 10.088 milli seconds C:\Users\srini\Desktop>