JAVA program to replace elements of integer array with product of other elements

An integer array refers to an array in which all elements are of integer type. It is also known as an array of integers.

As per the problem statement we have to create an Integer array and display the array elements where all the array elements are the product of other elements of the array.

In this article, we will see how to replace array elements by the product of other array elements by using Java programming language.

To show you some instances −

Instance-1

int arr[] = { 2, 3, 1, 4, 6 }
At Index-0 value will be = 3 * 1 * 4 * 6 = 72
At Index-1 value will be = 2 * 1 * 4 * 6 = 48
At Index-2 value will be = 2 * 3 * 4 * 6 = 144
At Index-3 value will be = 2 * 3 * 1 * 6 = 36
At Index-4 value will be = 2 * 3 * 1 * 4 = 24
So, the updated array elements are {72, 48, 144, 36, 24}

Instance-2

int arr[] = { 1, 3, 2, 4 }
At Index-0 value will be = 3 * 2 * 4 = 24
At Index-1 value will be = 1 * 2 * 4 = 8
At Index-2 value will be = 1 * 3 * 4 = 12
At Index-3 value will be = 1 * 3 * 2 = 6
So, the updated array elements are {24, 8, 12, 6}

Algorithm

Algorithm-1

Step-1 − Declare and initialize an integer array.

Step 2 - Find the product of all array elements.

Step-3 − Divide the product value with the value of the respective index and replace the result. Continue this step till you reach the last array element.

Step-4 − Print the updated array.

Algorithm-2

Step-1 − Declare and initialize an integer array.

Step-2 − Find the product of left sub array elements. The elements before the respective element to be replaced.

Step-3 − Find the product of the right subarray elements. The element after the element to be replaced.

Step-4 − Find the sum of the product values ​​of the left subarray and the right subarray, and replace it with the result value.

Step-5 − Continue Step-2, 3 and 4 till you reach the last array element.

Step-6 − Print the updated array.

Syntax

To get the length of an array (number of elements in that array), there is an inbuilt property of array i.e length.

Below refers to the syntax of it −

array.length

where, ‘array’ refers to the array reference.

To get the String representation of the respective array we can use the toString() method of Arrays class in Java.

Arrays.toString(A)

Multiple methods−

We have provided the solution in different approaches.

• By dividing the respective index elements by the total product value

• By finding the product value of the left subarray and the right subarray

Let's look at the program and its output one by one.

Approach-1 − By Dividing the respective Index Element with the Total Product Value

In this method we will replace the array elements by dividing the total product value by the corresponding element to be replaced.

Example

import java.util.Arrays;
public class Main {
   public static void main(String args[]) {
      //Declare and initialize the array elements
      int arr[] = { 2, 3, 1, 4, 6 };
      // Print the array elements
      System.out.println("Array elements are: "+Arrays.toString(arr));
      //Declare an int variable 'product' to hold the product value
      int product = 1;
      //iterate the array elements and find the product of all elements
      for(int i=0;i<arr.length;i++) {
         product*=arr[i];
      }
      //Divide the total product value with the array element to be replaced
      for(int i=0;i<arr.length;i++) {
         arr[i] = product/arr[i];
      }
      //print the new array
      System.out.println("Updated array: "+Arrays.toString(arr));
   }
}

Output

Array elements are: [2, 3, 1, 4, 6]
Updated array: [72, 48, 144, 36, 24]

Approach-2 − By Finding the Product Values ​​of Left and Right Sub Array

In this approach, we will replace the array element finding the sum of product of left subarray elements and product of right sub array elements.

Example

import java.util.Arrays;
public class Main{
   public static void main(String args[]) {
      int arr[] = {4,2,3,1};
      int size=arr.length;
      int temp[]= new int[size];
      int sum=1;
      System.out.println("Array elements are: "+Arrays.toString(arr));
      for(int index=0; index<arr.length; index++) {
         int leftProduct=1;
         int rightProduct=1;
         int i=0;
         if(i<index) {
            for(i=0;i<index;i++) {
               leftProduct*=arr[i];
            } 
         }
         for(i=index+1;i<arr.length;i++){
            rightProduct*=arr[i];
         }
         sum=leftProduct*rightProduct;
         temp[index]=sum;
      }
      arr=temp;
      System.out.println("Updated array: "+Arrays.toString(arr));
   }
}

Output

Array elements are: [4, 2, 3, 1]
Updated array: [6, 12, 8, 24]

In this article, we explored how to replace array elements with the product of other array elements in Java using different methods.

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