/./././/././././././././/.

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Semaphore;

public class BarberShop {

    static  int waitingCustomers = 0;

    static Semaphore berber = new Semaphore(0);
    static Semaphore client = new Semaphore(5);
    static Semaphore lock = new Semaphore(1);

    static class Barber extends Thread{

        BarberShop barberShop;

        public Barber (BarberShop barberShop){
            this.barberShop= barberShop;
        }
        public void execute() throws InterruptedException {

            berber.acquire();
            lock.acquire();
            waitingCustomers--;
            barberShop.barber();
            if (waitingCustomers == 0){
                client.release(5);
            }
            lock.release();

        }
        @Override
        public void run() {

            for (int i=0;i<100; i++)
                try {
                    execute();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
        }
    }

    static class Costumer extends Thread{

        BarberShop barberShop;

        public Costumer (BarberShop barberShop){
            this.barberShop= barberShop;
        }
        public void execute() throws InterruptedException {

            client.acquire();
            lock.acquire();
            waitingCustomers++;
            barberShop.customerComesIn();

            if(waitingCustomers==5){
                berber.release(5);
            }

            lock.release();



        }
        @Override

        public void run() {

            for (int i = 0; i < 1; i++) {

                try {
                    execute();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    void customerComesIn() throws InterruptedException {
        // TODO: 3/29/20 Synchronize this method, invoked by a Customer thread
        System.out.println("Costumer comes in");
    }

    void barber() throws InterruptedException {
        // TODO: 3/29/20 Synchronize this method, invoked by Barber thread
        System.out.println("Barber working");

    }

    public static void main(String[] args) throws InterruptedException {
        // TODO: 3/29/20 Synchronize the scenario

        BarberShop barberShop = new BarberShop();
        Barber b = new Barber(barberShop);
        List<Costumer> costumers =new ArrayList<>();
        for (int i=0 ; i<100 ; i++){
            costumers.add(new Costumer(barberShop));
        }

        b.start();
        for (Costumer c :costumers){
            c.start();
        }
        b.join();
        for (Costumer c :costumers){
            c.join(5);
        }

        System.out.println("Uspeshna sinhronizacija");
    }
}