Question

Assignment Purpose

The purpose of this lab is to write a well commented java program that demonstrates the use of one dimensional arrays and methods.

Instructions

1. Write a method rotateArray that is passed to an array, x, of integers (minimum 7 numbers) and an integer rotation count, n. x is an array filled with randomly generated integers between 1 and 100.
2. The method creates a new array with the items of x moved forward by n Elements that are rotated off the array will appear at the end. Forward rotation means moving elements from right to left on paper. For example, suppose x contains the following items in sequence:

1 2 3 4 5 6 7 and the value of n = 3

3. Your program should first calculate the sum of numbers at even indexes (consider 0 as even) which in this case is 1 + 3 + 5 + 7 = 16, and then average of numbers at odd indexes which in this case is (2 + 4 + 6) / 3 = 4.
4. After that it should make a call to rotateArray with arguments as x and n.

Sample output

-----------------------Output Begins-------------------------

The randomly generated integers in array are: 1 2 3 4 5 6 7

Sum of numbers at even indexes = 16

Average of numbers at odd indexes = 4

Enter rotation count: 3

Calling rotateArray with rotation count as 3………

After 1^st rotation the array contents are         2 3 4 5 6 7 1

After 2^nd rotation the array contents are        3 4 5 6 7 1 2

After 3^rd rotation the array contents are        4 5 6 7 1 2 3

-----------------------End of Output----------------------------

So after rotating by 3, the elements in the new array will appear in this sequence:

4 5 6 7 1 2 3

Answer 1

Following is the answer:

import java.util.Random;
import java.util.Scanner;

public class RotateArray {
void leftRotate(int arr[], int d, int n)
{
for (int i = 0; i < d; i++) {
leftRotatebyOne(arr, n);
printArray(arr, n);
System.out.println("\n");
}
}

void leftRotatebyOne(int arr[], int n)
{
int i, temp;
temp = arr[0];
for (i = 0; i < n - 1; i++)
arr[i] = arr[i + 1];
arr[i] = temp;
}

void printArray(int arr[], int n)
{
for (int i = 0; i < n; i++)
System.out.print(arr[i] + " ");
}

void sumOfEven(int arr[], int n){
int sum = 0;
double avg = 0;
int sum2 = 0;
int count = 0;
for(int i = 0 ; i < n ; i++){

if(i%2 == 0){
sum+= arr[i];
}else {
sum2+= arr[i];
count++;
}
}
System.out.println("\nSum of numbers at even indexes = " + sum);
System.out.println("Average of numbers at odd indexes = " + (sum2/count));
}

// Driver program to test above functions
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
int n, count;

RotateArray rotate = new RotateArray();

System.out.println("Enter array size:");
n = sc.nextInt();

int arr[] = new int[n];
Random rand = new Random();
for (int i = 0; i < n; i++) {
arr[i] = rand.nextInt(100-1) + 1;
}
System.out.println("The randomly generated integers in array are: ");
rotate.printArray(arr, n);
rotate.sumOfEven(arr, 7);
System.out.println("Enter rotation count: ");
count = sc.nextInt();
rotate.leftRotate(arr, count, n);
}
}

Output: