Java: Find the sum of the two elements of a given array which is equal to a given integer

Java Array: Exercise-35 with Solution

Write a Java program to find the sum of the two elements of a given array equal to a given .
Sample array: [1,2,4,5,6]
Target value: 6.

Pictorial Presentation:

Sample Solution:

Java Code:

// Import the required classes from the java.util package.
import java.util.*;

// Define a class named Exercise35.
public class Exercise35 {
    // Define a method named two_sum_array_target that takes a List of integers and an integer as input.
    public static ArrayList<Integer> two_sum_array_target(final List<Integer> a, int b) {
        // Create a HashMap to store the difference between the target value and array elements.
        HashMap<Integer, Integer> my_map = new HashMap<Integer, Integer>();

        // Create an ArrayList to store the result indices.
        ArrayList<Integer> result = new ArrayList<Integer>();
        result.add(0); // Initialize the first index to 0.
        result.add(1); // Initialize the second index to 1.

        // Iterate through the elements of the input List.
        for (int i = 0; i < a.size(); i++) {
            if (my_map.containsKey(a.get(i))) {
                // If the current element's complement exists in the HashMap, update the result indices and break the loop.
                int index = my_map.get(a.get(i));
                result.set(0, index);
                result.set(1, i);
                break;
            } else {
                // Otherwise, calculate the difference between the target value and the current element and store it in the HashMap.
                my_map.put(b - a.get(i), i);
            }
        }

        // Return the result ArrayList containing the indices.
        return result;
    }

    // The main method for executing the program.
    public static void main(String[] args) {
        // Create an ArrayList of integers and add elements to it.
        ArrayList<Integer> my_array = new ArrayList<Integer>();
        my_array.add(1);
        my_array.add(2);
        my_array.add(4);
        my_array.add(5);
        my_array.add(6);
        int target = 6;

        // Call the two_sum_array_target method to find indices of elements that sum to the target value.
        ArrayList<Integer> result = two_sum_array_target(my_array, target);

        // Print the indices found in the result.
        for (int i : result) {
            System.out.print("Index: " + i + " ");
        }
    }
}

Sample Output:

                                                                              
Index: 1 Index: 2

Flowchart:

Java Code Editor:

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