Question

I need help with this .java implementation:

Implement an algorithm that given two sorted arrays of size m and n creates a sorted array of size (n + m) in O(n + m) time.

The script must take as an input a command line argument specifying the name of a .txt file which will contain the arrays to be sorted.

Each line in the .txt file will contain two arrays, with elements in arrays separated by commas and the arrays themselves separated by semicolons (e.g. 1,2,7,8;3,4,9,10). For each line in the input file your script should print out the elements in the new sorted array separated by spaces.

Answer 1

Code is as follows:

Main.java

************************************************************************************************************************************

import java.io.*;
import java.util.Scanner;
public class Main
{
public static int[] mergeArrays(int arr1[], int arr2[], int m, int n) {
int i = 0, j = 0, k = 0;
int arr3[] = new int[m+n];
// Traverse both array
while (i<m && j <n)
{
// Check if current element of first
// array is smaller than current element
// of second array. If yes, store first
// array element and increment first array
// index. Otherwise do same with second array
if (arr1[i] < arr2[j])
arr3[k++] = arr1[i++];
else
arr3[k++] = arr2[j++];
}
  
// Store remaining elements of first array
while (i < m)
arr3[k++] = arr1[i++];
  
// Store remaining elements of second array
while (j < n)
arr3[k++] = arr2[j++];
  
return arr3;
}
   public static void main(String[] args) {
       try {
//the file to be opened for reading
FileInputStream fis=new FileInputStream(args[0]);   
Scanner sc=new Scanner(fis); //file to be scanned
//returns true if there is another line to read
while(sc.hasNextLine()){
String s = sc.nextLine(); //read the line in String
String s1[] = s.split(";"); //split the string using ; to get two arrays
String arr1[] = s1[0].split(","); //split the first array with ,
String arr2[] = s1[1].split(","); //split the second array with ,
int array1[] = new int[arr1.length]; //a Integer array to store array 1
int array2[] = new int[arr2.length]; // a Integer array to store array 2
for(int i=0;i<arr1.length;i++){
array1[i] = Integer.parseInt(arr1[i]); //parse the string array and store in int array
}
for(int i=0;i<arr2.length;i++){
array2[i] = Integer.parseInt(arr2[i]); //parse the string array and store in int array

}
int result[] = mergeArrays(array1,array2,array1.length,array2.length); // get the resultant array
for(int i = 0 ; i < result.length ; i++ ){
System.out.print(result[i]+" "); // print the result
}
System.out.println(); // next Line
}
sc.close(); //closes the scanner
}
catch(IOException e){
e.printStackTrace();
}
   }
}

************************************************************************************************************************************

Input file:

arrays.txt

1,2,7,8;3,4,9,10
1,2,5;0,10,15
1,4,10;2,5,19,23
2,4,6,9;1,5,8,14,29

***********************************************************************************************************************************

Screenshot of the code:

text file screenshot:

Output: