Java Program to Find Minimum Product of Two Integers in an Array

In the previous article, we have seen Java Program to Find Maximum Sum of Two Integers in an Array

In this article we are going to see how we can find minimum product of two integers in an array.

Java Program to Find Minimum Product of Two Integers in an Array

As we have to write a program which will find the minimum product of two integers in an array of integers so our first target should be finding first two smallest numbers from the array elements. As it is very much clear that product of two smaller numbers will give minimum product value than product of two bigger numbers.

For example:

If we have an array say arr=[1, 7, 4, 2, 8, 6, 3, 9, 5]
Then in this array first two smaller numbers are 1 and 2.
So product is 1*2=2 which is maximum product value we can find than any other possible combinations of array elements.

Let’s see different ways to find minimum product of two integers in an array.

By Using Sorting Technique
By Finding First Two Biggest Element

Method-1: Java Program to Find Minimum Product of Two Integers in an Array By Using Sorting Technique

Approach:

Declare an array and with array elements.
Sort the array by using Arrays.sort() method.
Now array is sorted in ascending order.
So, find the product of first element and second element of the array which will give the minimum product value.
Print the result.

Program:

import java.util.Arrays;
import java.util.Comparator;
 
class Main
{
    public static void main(String[] args)
    {
        //integer array declared along with integer elements
        Integer[] input = { 1,6,3,4,5 };
        
        // sort the array in ascending order
        Arrays.sort(input);
        
        //as array is sorted in ascending order
        //so first two elements are smallest elements
        //so by multiplying the first two elements we will get minimum product
        long result=input[0]*input[1];
        //input[input.length-1] represents last elements
        //input[input.length-2] second last element
        System.out.println("Two numbers are "+ input[0] +" and "+ input[1]+" having minimum product "+result);        
    }
}

Output:

Two numbers are 1 and 3 having minimum product 3

Method-2: Java Program to Find Minimum Product of Two Integers in an Array By Finding First Two Biggest Element

Approach:

Take user input of length of array.
Take input of integer array elements.
Call the user defined method findSmallest() to find first 2 small elements in the array say firstNumber, secondNumber
After getting 2 smallest elements in the array, inside that findSmallest() method, call findMinProduct() method.
Inside findMinProduct() method add firstNumber and secondNumber which will give the minimum product value.
Print the result.

Program:

import java.util.Scanner;

public class Main 
{
     public static void main(String args[]) 
    {
        int length = 0;
        Scanner sc = new Scanner(System.in);
        System.out.println("Enter number of elements in array: ");
        //array length taken as input
        length = sc.nextInt();
        //array declared
        int[] arr = new int[length];
        
        //take input of numbers as array element
        System.out.println("Enter elements into array: ");
        //taking input of array elements
        for (int i = 0; i < length; i++) 
        {
            arr[i] = sc.nextInt();
        }

        System.out.println("First 2 smallest numbers in array : ");
        //calling findSmallest() method
        findSmallest(arr);
    }
    
    //user defined method to find first 2 smallest element
    private static void findSmallest(int[] arr) 
    {
        //let first two numbers are the smaller numbers
        int firstNumber=arr[0];
        int secondNumber=arr[1];
        
        //loop to find 2 smallest numbers
        for (int i = 0; i < arr.length; i++) 
        { 
            if (arr[i] < firstNumber) 
            {
                secondNumber = firstNumber;
                firstNumber = arr[i];
            } 
            else if (arr[i] < secondNumber) 
            {
                secondNumber = arr[i];
            }
        }

        System.out.println("First smallest number : " + firstNumber);
        System.out.println("Second smallest number : " + secondNumber);
        
        //calling findMinProduct() method to find minimum product value
        findMinProduct(firstNumber,secondNumber);
    }
    
    public static void findMinProduct(int firstNumber, int secondNumber)
    {
        //multiplying both numbers to find summation value
        int result= firstNumber*secondNumber;
        System.out.println("Two numbers are "+ firstNumber +" and "+ secondNumber+" having minimum product "+result);
    }
}

Output:

Enter number of elements in array: 
5
Enter elements into array: 
40 10 30 50 20
First 2 smallest numbers in array : 
First smallest number : 10
Second smallest number : 20
Two numbers are 10 and 20 having minimum sum 30

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