Example: DisjointArrayHashSet in Java

// DisjointArrayHashSet
import java.util.HashSet;
import java.util.Scanner;

// Main class containing the entry point of the program
public class Main {
    /**
     * Checks if two integer arrays are disjoint using a HashSet.
     * @param arr1 The first array.
     * @param arr2 The second array.
     * @return true if the arrays are disjoint (no common elements), false otherwise.
     */
    public static boolean areArraysDisjointHashSet(int[] arr1, int[] arr2) {
        // Step 1: Create a HashSet to store elements from the first array.
        HashSet<Integer> set = new HashSet<>();

        // Step 2: Add all elements of arr1 to the HashSet.
        for (int element : arr1) {
            set.add(element);
        }

        // Step 3: Iterate through each element of the second array.
        for (int element : arr2) {
            // Step 4: Check if the current element from arr2 exists in the HashSet.
            if (set.contains(element)) {
                // Step 5: If it exists, a common element is found, so arrays are not disjoint.
                return false;
            }
        }
        // Step 6: If no common elements are found after checking all elements of arr2, the arrays are disjoint.
        return true;
    }

    public static void main(String[] args) {
        // Test Case 1: Disjoint arrays
        int[] arr1_case1 = {1, 2, 3};
        int[] arr2_case1 = {4, 5, 6};
        System.out.println("Arrays: {1, 2, 3} and {4, 5, 6}");
        System.out.println("Are disjoint (HashSet)? " + areArraysDisjointHashSet(arr1_case1, arr2_case1)); // Expected: true

        // Test Case 2: Non-disjoint arrays
        int[] arr1_case2 = {1, 2, 3};
        int[] arr2_case2 = {3, 4, 5};
        System.out.println("\nArrays: {1, 2, 3} and {3, 4, 5}");
        System.out.println("Are disjoint (HashSet)? " + areArraysDisjointHashSet(arr1_case2, arr2_case2)); // Expected: false

        // Test Case 3: Empty arrays
        int[] arr1_case3 = {};
        int[] arr2_case3 = {1, 2, 3};
        System.out.println("\nArrays: {} and {1, 2, 3}");
        System.out.println("Are disjoint (HashSet)? " + areArraysDisjointHashSet(arr1_case3, arr2_case3)); // Expected: true
    }
}