SchoolBus sync

package kol2015g1;

import java.util.Date;
import java.util.HashSet;
import java.util.concurrent.Semaphore;
import problem.ProblemExecution;
import problem.TemplateThread;

/**
 *
 * @author ristes
 *
 */

public class SchoolBusSolution {
    public static Semaphore blokirajStudentiVlez;
    public static Semaphore blokirajStudentiVlez1;
    public static Semaphore blokirajStudentIzlez;
    public static Semaphore blokirajVozac;
    public static Semaphore blokirajTrgvenje;
    public static Semaphore lock;
    public static Semaphore edinstvenVozac;
    public static int brojac;

    public static void init() {
        blokirajStudentiVlez = new Semaphore(0);
        blokirajStudentiVlez1 = new Semaphore(0);
        blokirajStudentIzlez = new Semaphore(0);
        blokirajVozac = new Semaphore(0);
        lock = new Semaphore(1);
        brojac = 0;
        edinstvenVozac = new Semaphore(1);
        blokirajTrgvenje = new Semaphore(0);
    }

    public static class Driver extends TemplateThread {

        public Driver(int numRuns) {
            super(numRuns);
        }

        @Override
        public void execute() throws InterruptedException {
            edinstvenVozac.acquire();

            lock.acquire();
            state.driverEnter();
            blokirajStudentiVlez.release(50);
            lock.release();

            blokirajTrgvenje.acquire();
            state.busDeparture();
            state.busArrive();
            blokirajStudentIzlez.release(50);

            blokirajVozac.acquire();
            state.driverLeave();
            edinstvenVozac.release();
        }
    }

    public static class Student extends TemplateThread {

        public Student(int numRuns) {
            super(numRuns);
        }

        @Override
        public void execute() throws InterruptedException {
            blokirajStudentiVlez.acquire();


            lock.acquire();
            brojac++;
            state.studentEnter();
            if (brojac == 50) {
                blokirajTrgvenje.release();
            }
            lock.release();


            blokirajStudentIzlez.acquire();


            lock.acquire();
            state.studentLeave();
            brojac--;
            if (brojac == 0){
                blokirajVozac.release();
            }
            lock.release();


        }
    }

    static SchoolBusState state = new SchoolBusState();

    public static void main(String[] args) {
        for (int i = 0; i < 10; i++) {
            run();
        }
    }

    public static void run() {
        try {
            int numRuns = 1;
            int numScenarios = 50;
            HashSet<Thread> threads = new HashSet<Thread>();

            for (int i = 0; i < numScenarios; i++) {
                Student p = new Student(numRuns);
                threads.add(p);
                if (i % 50 == 0) {
                    Driver c = new Driver(numRuns);
                    threads.add(c);
                }
            }

            init();

            ProblemExecution.start(threads, state);
            System.out.println(new Date().getTime());
        } catch (Exception ex) {
            ex.printStackTrace();
        }

    }
}