Test.java

package com.cloudimpl.beep;

/**
 * @author danushka
 * 2023-05-08
 */

import java.util.*;
import java.util.stream.Collectors;

class Test {
    public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);

        System.out.print("Enter the size of array A: ");
        int n1 = scanner.nextInt();
        ArrayList<Integer> arr1 = new ArrayList<>();

        System.out.println("Enter the elements of array A:");
        for (int i = 0; i < n1; i++) {
            arr1.add(i, scanner.nextInt());
        }


        System.out.print("Enter the size of array B: ");
        int n2 = scanner.nextInt();
        ArrayList<Integer> arr2 = new ArrayList<>();


        System.out.println();

        System.out.println("Enter the elements of array B:");
        for (int i = 0; i < n2; i++) {
            arr2.add(i, scanner.nextInt());
        }


        System.out.print("[");
        for (int i = 0; i < arr1.size(); i++) {
            System.out.print(arr1.get(i) + " ");
        }
        System.out.println("]");

        System.out.print("[");
        for (int i = 0; i < arr2.size(); i++) {
            System.out.print(arr2.get(i) + " ");
        }
        System.out.println("]");


        int result = solution(arr1, arr2);
        System.out.println("Result = " + result);
    }

    public static int solution(List<Integer> a, List<Integer> b) {
        Set<String> result = new HashSet<>();
        result.add("[" + a.stream().map(String::valueOf).collect(Collectors.joining(", ")) + "]");
        result.add("[" + b.stream().map(String::valueOf).collect(Collectors.joining(", ")) + "]");
        for (int i = 0; i < a.size(); i++) {
            for (int j = 0; j < b.size(); j++) {
                List<String> nonDecreasingArray = getCombination(a, b, i, j);
                result.addAll(nonDecreasingArray);
            }
        }
        return result.size() - 2;
    }

    private static List<String> getCombination(List<Integer> a, List<Integer> b, int i, int j) {
        List<Integer> copyOfA = new ArrayList<>(a);
        List<Integer> copyOfB = new ArrayList<>(b);

        copyOfA.set(i, b.get(j));
        copyOfB.set(j, a.get(i));
        if (isNonDecreasingArray(copyOfA) && isNonDecreasingArray(copyOfB)) {
            return List.of(copyOfA.toString(), copyOfB.toString());
        } else {
            return Collections.emptyList();
        }
    }

    private static boolean isNonDecreasingArray(List<Integer> array) {
        for (int i = 0; i < array.size() - 1; i++) {
            if (array.get(i) > array.get(i + 1)) {
                return false;
            }
        }
        return true;
    }

}