import java.util.*;
import java.util.stream.IntStream;

public class Solution {
    public static void main(String[] args) {
        int[] randomArray = IntStream.generate(() -> new Random().nextInt(10)).limit(10).toArray();
        int a = new Random().nextInt(10);
        System.out.println("Search for all pairs of numbers " + Arrays.toString(randomArray) + " the sum of which is equal " + a);

        Map<Integer, Integer> pairs = new HashMap<>();
        for (int i : randomArray) {
            if (pairs.containsKey(i)) {
                if (pairs.get(i) != null) {
                    System.out.println(i + "+" + (a-i) + "=" + a);
                }
                pairs.put(a-i, null);
            } else if (!pairs.containsValue(i)) {
                pairs.put(a-i, i);
            }
        }
    }
}