Example: DisjointArraySortAndPointers in Java

// DisjointArraySortAndPointers
import java.util.Arrays;
import java.util.Scanner;

// Main class containing the entry point of the program
public class Main {
    /**
     * Checks if two integer arrays are disjoint by sorting and using two pointers.
     * @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 areArraysDisjointSortAndPointers(int[] arr1, int[] arr2) {
        // Step 1: Sort both arrays.
        Arrays.sort(arr1);
        Arrays.sort(arr2);

        // Step 2: Initialize two pointers, one for each array.
        int i = 0; // Pointer for arr1
        int j = 0; // Pointer for arr2

        // Step 3: Iterate while both pointers are within their respective array bounds.
        while (i < arr1.length && j < arr2.length) {
            // Step 4: If elements at current pointers are equal, a common element is found.
            if (arr1[i] == arr2[j]) {
                return false; // Not disjoint
            }
            // Step 5: If element in arr1 is smaller, move arr1's pointer forward.
            else if (arr1[i] < arr2[j]) {
                i++;
            }
            // Step 6: If element in arr2 is smaller, move arr2's pointer forward.
            else { // arr1[i] > arr2[j]
                j++;
            }
        }
        // Step 7: If the loops complete without finding any common elements, the arrays are disjoint.
        return true;
    }

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

        // Test Case 2: Non-disjoint arrays
        int[] arr1_case2 = {2, 1, 3}; // Unsorted initially
        int[] arr2_case2 = {5, 3, 4}; // Unsorted initially
        System.out.println("\nArrays: {2, 1, 3} and {5, 3, 4}");
        System.out.println("Are disjoint (Sort & Pointers)? " + areArraysDisjointSortAndPointers(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 (Sort & Pointers)? " + areArraysDisjointSortAndPointers(arr1_case3, arr2_case3)); // Expected: true
    }
}