Get the Triplets in an Array Whose Sum is Equal to a Specific Number in Java

In Java, Array is an object. It is a non-primitive data type which stores values of similar data type.

As per the problem statement we have to get all the triplets in the array whose sum is equal to a specific number. Here triplets refer to any three elements of the array which meet a specific condition.

Note − The array must be an integer array.

Let’s explore the article to see how it can be done by using Java programming language.

To Show You Some Instances

Instance-1

Suppose the original array is {3, 4, 25, 6, 13, 9}.

After performing the triplet operation to get sum equal to 37, the result will be −

The triplet is 3, 25, 9. 

Instance-2

Suppose the original array is {11, 4, 5, 6, 21, 29}

After performing the triplet operation to get sum equal to 22, the result will be −

The triplet is 11, 5, 6.

Instance-3

Suppose the original array is {8, 2, 15, 6, 11, 1}

After performing the triplet operation to get sum equal to 14, the result will be −

The triplet is 2, 11, 1.

Algorithm

• Step 1 − Declare and initialize an integer array.

• Step 2 − Declare the sum whose triplet needs to be found out.

• Step 3 − Initialize three for loops one inside another to find out the triplet element.

• Step 4 − Check if the three elements are equal to the sum.

• Step 5 − Print the triplet.

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.

Multiple Approaches

We have provided the solution in different approaches.

• By Using Static Initialization of Array

• By Using User Defined Method

Let’s see the program along with its output one by one.

Approach-1: By Using Static Initialization of Array

Example

In this approach, array elements will be initialized in the program. Then as per the algorithm get all the triplets in the array whose sum is equal to a specific number.

public class Main{
   //main method
   public static void main(String[] args){

      //Declare and initialize the array elements
      int arr[] = {11, 4, 5, 6, 21, 29};

      //a particular number whose triplet meeds to be find out
      int sum = 15;

      // Fix the first element as a[i]
      for (int i = 0; i < arr.length - 2; i++) {

         // Fix the second element as a[j]
         for (int j = i + 1; j < arr.length - 1; j++) {
            // Now look for the third number in an array
            for (int k = j + 1; k < arr.length; k++) {             
               if (arr[i] + arr[j] + arr[k] == sum) {

                  //printing the triplet
                  System.out.print("The triplet is " + arr[i] + ", " + arr[j] + ", " + arr[k] + ".");
               }
            }
         }
      }
   }
}

Output

The triplet is 4, 5, 6.

Approach-2: By Using User Defined Method

Example

In this approach, array elements will be initialized in the program. Then call a user defined method by passing the array as parameter and inside the method as per the algorithm get all the triplets in the array whose sum is equal to a specific number.

public class Main{
   //main method
   public static void main(String[] args){

      //Declare and initialize the array elements
      int arr[] = { 8, 2, 15, 6, 11, 1 };

      //calling user defined method
      triplet(arr);
   }

   //user defined method
   public static void triplet(int []arr){

      //a particular number whose triplet meeds to be find out
      int sum = 14;

      // Fix the first element as a[i]
      for (int i = 0; i < arr.length - 2; i++) {
         // Fix the second element as a[j]
         for (int j = i + 1; j < arr.length - 1; j++) {
            // Now look for the third number in an array
               for (int k = j + 1; k < arr.length; k++) {              
                  if (arr[i] + arr[j] + arr[k] == sum) {

                  //printing the triplet
                  System.out.print("The triplet is " + arr[i] + ", " + arr[j] + ", " + arr[k] + ".");
               }
            }
         }
      }
   }
}

Output

The triplet is 2, 11, 1.

In this article, we explored how to get all the triplets in the array whose sum is equal to a specific number in Java.