CareerCup

A solution in q language:

f:{ / function to sort the elements of the array
    c0::c1::c2::0; / counter variables
    {$[0=x;c0+:1;1=x;c1+:1;2=x;c2+:1;::]} each x; / inner function to count occurence of each element
    :raze [[(c0;c1;c2)]{#[x;y]}'til 3]; / returning the occurence of 0,1,2 based on count
    };

Test:
a:0 1 1 0 2 1 2; / array initialization
f a / calling the function
Output: 0 0 1 1 1 2 2

import java.util.concurrent.Callable;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

public class AddNumbersUsingExecutorService {

    public static void main(String[] args) throws Exception{
        // TODO Auto-generated method stub
        
        CopyOnWriteArrayList<Integer> al = new CopyOnWriteArrayList<>();
        
        AddNumService[] an = {new AddNumService(10, 20),
                new AddNumService(30, 40)
        };
        
        ExecutorService service = Executors.newFixedThreadPool(2);
        for(AddNumService an1 : an){
            Future<Integer> f = service.submit(an1);
            al.add(f.get());
        }
        service.shutdown();
        System.out.println(al.get(0) * al.get(1));
        al = null;
    }

}

class AddNumService implements Callable<Integer>{
    int num1, num2;
    public AddNumService(int num1, int num2) {
        // TODO Auto-generated constructor stub
        this.num1 = num1;
        this.num2 = num2;
    }

    @Override
    public Integer call() throws Exception {
        // TODO Auto-generated method stub
        System.out.println(Thread.currentThread().getName());
        return num1 + num2;
    }
    
}