Question

Write a JAVA program that rotates a 1-dimensional by 2 elements. For example [1,2,3,4,5,6] rotated by two becomes [3,4,5,6,1,2].

Answer 1

File Name:

LeftRotatoin.java

Program:

import java.util.Scanner;
class LeftRotation
{
   public static void main(String[] args) {

       // Declaring a Scanner variable for taking input
       Scanner in = new Scanner(System.in);
       // Taking the no.of elements of the array and storing
       // it in variable n.
       System.out.println("Enter no.of values");
       int n=in.nextInt();

       // Taking the elements of the Array and storing it in the
       // array arr.
       System.out.println("Enter numbers");
       int[] arr = new int[n];
       for(int i=0; i<n; i++)
       {
           arr[i] = in.nextInt();
       }

       // Printing the array that we've taken.
       System.out.println("\nArray that you've entered:");
       for(int i=0; i<n; i++)
       {
           System.out.print(arr[i]+" ");
       }  

       // Create a new array to store the resulting values.
       int[] result = new int[n];

       // If we rotate an array of lenth "n" by "r" positions,
       // then the values at an index "i" will be moved to an index
       // position which is equal to (i-r+n)%n which means that,
       // "i" is moved to "r" places left and then, since, we have to
       // neutralize the negative sign (Which might come) we
      // are adding "n" and since, the values should be in
      // range 0...n-1, we are finding modulus of the obtained
      // number (i-r+n) with n. Thus making the new index in range of the 0...n-1

       //here r is 2
       for(int i=0; i<n; i++)
       {
           // you can replace 2 with whatever integer
           // and this rotates the array that number times.
           result[(i-2+n)%n] = arr[i];
       }

       // Printing the array after rotation.
       System.out.println("\n\nAfter Rotaion: ");
       for(int i=0; i<n; i++)
       {
           System.out.print(result[i]+" ");
       }
   }
}

Output:

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