Question

Write a program to merge two sorted arrays into a third array. Ask the user to enter the size of the two arrays. The length of array1 could be greater than, equal to or less than the length of array2. Fill both with random numbers 0-99. Sort both arrays as explained below. Write a method merge that takes the two arrays as arguments. The method returns a merged array with size equal to the size of both arrays combined. Note: You may not create the third array and then sort it. The two arrays passed as arguments must be sorted. CSCI 125 Array exercises Prof. Kadri

To sort an array, java.util.Arrays is a library that has a method sort that sorts an array. To use it, you will need to import java.util.Arrays. Arrays.sort(array); // will sort array in ascending order

Example: Enter the size of array1: 10

Enter the size of array2: 4

Array1: 7 2 3 8 6 6 75 38 3 2

Array2: 5 4 3 2

Sort the two arrays Array1: 2 2 3 3 6 6 7 8 38 75 Array2: 2 3 4 5 Merging Array3: 2 2 2 3 3 3 4 5 6 6 7 8 38 75

Answer 1

Java Program:

import java.util.*;

public class Main
{
   //Main function
public static void main(String args[])
   {
       //Random object
       Random rand = new Random();
      
       //Declaring size variables
       int arr1Size, arr2Size;
      
       //Scanner class object
       Scanner reader = new Scanner(System.in);
      
       //Reading size
       System.out.print("Enter the size of array1: ");
       arr1Size = reader.nextInt();
      
       System.out.print("Enter the size of array2: ");
       arr2Size = reader.nextInt();
      
       //Declaring arrays
       int[] arr1 = new int[arr1Size];
       int[] arr2 = new int[arr2Size];
      
       //Filling arrays with random numbers
       for(int i=0; i<arr1Size; i++)
       {
           arr1[i] = rand.nextInt(100);  
       }
      
       //Filling arrays with random numbers
       for(int i=0; i<arr2Size; i++)
       {
           arr2[i] = rand.nextInt(100);  
       }
      
       System.out.println("\n Array1 : " + Arrays.toString(arr1));
       System.out.println("\n Array2 : " + Arrays.toString(arr2));
      
       //Sorting arrays
       Arrays.sort(arr1);
       Arrays.sort(arr2);
      
       //Result array
       int[] res = new int[arr1Size + arr2Size];
      
       //Calling merge function
       res = merge(arr1, arr1Size, arr2, arr2Size);
      
       //Printing results
       System.out.println("\nSort the two arrays\n");
       System.out.println("\n Array1 : " + Arrays.toString(arr1));
       System.out.println("\n Array2 : " + Arrays.toString(arr2));
       System.out.println("\n Merging Array3 : " + Arrays.toString(res) + "\n");
   }
  
   //Method that merges two arrays
   public static int[] merge(int[] firstList, int arr1Size, int[] secondList, int arr2Size)
   {
       int i, j, k=0;
      
       //Result
       int[] mergedList = new int[arr1Size + arr2Size];
      
       //Iterating over list elements
       for(i=0, j=0; i<arr1Size && j<arr2Size;)
       {
           //Comparing elements and then storing in resultant list
           if(firstList[i] < secondList[j])
           {
               mergedList[k] = firstList[i];
               i++;
               k++;
           }
           else
           {
               mergedList[k] = secondList[j];
               j++;
               k++;
           }
       }
      
       //Storing remaining elements
       while (i < arr1Size)
       {
           mergedList[k] = firstList[i];
           i++;
           k++;
       }
      
       //Storing remaining elements
       while (j < arr2Size)
       {
           mergedList[k] = secondList[j];
           j++;
           k++;
       }
          
       return mergedList;
   }
}

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