Question

Write a Java method that will take an array of integers of size n and shift right by m places, where n > m. You should read your inputs from a file and write your outputs to another file. Create at least 3 test cases and report their output.

I've created a program to read and write to separate files but i don't know how to store the numbers from the input file into an array and then store the new shifted array into an output file.  

****MY CODE*****

import java.io.File;

import java.io.FileNotFoundException;

import java.io.PrintWriter;

import java.util.Scanner;

public class shiftedArray {

public static void main(String[] args) throws FileNotFoundException {

File input = new File("inputFile.txt");

// this is main file to read from

PrintWriter output = new PrintWriter("OutputFile.txt");

//printwriter writes to the new file outputFile.txt

Scanner sc = new Scanner(input); //scans input file

//while loop to loop all lines from main file

while(sc.hasNextLine()) {

output.println(sc.nextLine());

}

//close scanner of input file and close new file output

sc.close();

output.close();

// TODO Auto-generated method stub

}

}

Answer 1

Java code:

import java.io.File;
import java.io.FileNotFoundException;
import java.io.PrintWriter;
import java.util.Scanner;
public class shiftedArray {
    public static void main(String[] args) throws FileNotFoundException {
        /**
         * For reading file
         */
        File input = new File("inputFile.txt");
        /**
         * For writing file
         */
        PrintWriter output = new PrintWriter("outputFile.txt");
        /**
         * Scanner class for reading file and reading from user
         * sc -- for reading from file
         * scan -- for reading from user
         */
        Scanner sc = new Scanner(input); //scans input file
        Scanner scan = new Scanner(System.in);
        /**
         * Reading size of array from user
         */
        System.out.print("Enter size of array: ");
        int n = scan.nextInt();
        /**
         * creating array of size n to read n integers from file
         */
        int[] arr = new int[n];
        int i = 0; // index in array
        /**
         * Reading n integers from file
         */
        while(i<n && sc.hasNextInt()) {
            int val = sc.nextInt();
            arr[i] = val; // storing in array at index i
            i++; // increase index by 1
        }
        /**
         * reading value of m which denotes the right shift count
         */
        System.out.print("Enter value of m: ");
        int m = scan.nextInt();
        /**
         * Rotating m right shift of array
         */
        
        
        /**
         * Creating a temp array of size m to store the last m integers of array 
         */
        int[] temp = new int[m];
        int j = n - 1;
        for(i = m-1;i>=0;i--,j--) {
            temp[i] = arr[j];
        }
        /**
         * shifting first (n-m) integers to m index right
         */
        for(i=n-m-1;i>=0;i--) {
            arr[i+m] = arr[i];
        }
        /**
         * Put last m integers in the starting of array to complete the process of rotating of array
         */
        for(i=0;i<m;i++) {
            arr[i] = temp[i];
        }
        /**
         * Writing the array integers in file after right shifting
         */
        for(i=0;i<n;i++)
            output.print(arr[i] + " ");
        /**
         * closing the files
         */
        sc.close();
        output.close();
    }
}

Input file content (inputFile.txt):

5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115

Sample input 1:

Enter size of array: 10 Enter value of m: 3

Sample output 1:

40 45 50 5 10 15 20 25 30 35 

Sample input 2:

Enter size of array: 5 Enter value of m: 4

Sample output 2:

10 15 20 25 5 

Sample input 3:

Enter size of array: 15 Enter value of m: 7

Sample output 3:

45 50 55 60 65 70 75 5 10 15 20 25 30 35 40 

Screenshot of code:

import java.io.File; import java.io.FileNotFoundException; import java.io.PrintWriter; import java.util.Scanner; public class shiftedArray { public static void main(String[] args) throws FileNotFoundException { File input = new File( pathname: "inputFile.txt"); PrintWriter output = new PrintWriter(FileName: "outputFile.txt"); Scanner sc = new Scanner(input); //scans input file Scanner scan = new Scanner(System.in); System.out.print("Enter size of array: "); int n = scan.nextInt(); int[] arr = new int[n]; int i = 0; while(i<n && sc. hasNextInt() { int val = sc.nextInt(); arr[i] = val; i++; System.out.print("Enter value of m: "); int m = scan.nextInt(); int[] temp = new int[m]; int j = n - 1; for(i = m-1;i>=0; i--,)--) { temp[i] = arr[j]; for(i=n-m-1;i>=0; i--) { arr[i+m] = arr[i]; for(i=0:i<m:i++) {

for(i=0;i<m;i++) { arr[i] = temp[i]; for(i=0;i<n;i++) output.print(arr[i] + " "); sc.close(); output.close(); 36 37 } }

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