import java.util.concurrent.Semaphore;

public class DiningPhilosophers {
    // Number of philosophers
    private static final int NUM_PHILOSOPHERS = 5;

    static class Philosopher implements Runnable {
        private final int id;
        private final Semaphore leftFork;
        private final Semaphore rightFork;

        public Philosopher(int id, Semaphore leftFork, Semaphore rightFork) {
            this.id = id;
            this.leftFork = leftFork;
            this.rightFork = rightFork;
        }

        @Override
        public void run() {
            try {
                while (true) {
                    think();
                    pickUpForks();
                    eat();
                    putDownForks();
                }
            } catch (InterruptedException e) {
                Thread.currentThread().interrupt();
            }
        }

        private void think() throws InterruptedException {
            System.out.println("Philosopher " + id + " is thinking.");
            Thread.sleep((long) (Math.random() * 1000));
        }

        private void eat() throws InterruptedException {
            System.out.println("Philosopher " + id + " is eating.");
            Thread.sleep((long) (Math.random() * 1000));
        }

        private void pickUpForks() throws InterruptedException {
            leftFork.acquire();
            rightFork.acquire();
        }

        private void putDownForks() {
            leftFork.release();
            rightFork.release();
        }
    }

    public static void main(String[] args) {
        Semaphore[] forks = new Semaphore[NUM_PHILOSOPHERS];
        for (int i = 0; i < NUM_PHILOSOPHERS; i++) {
            forks[i] = new Semaphore(1);
        }

        Philosopher[] philosophers = new Philosopher[NUM_PHILOSOPHERS];
        for (int i = 0; i < NUM_PHILOSOPHERS; i++) {
            Semaphore leftFork = forks[i];
            Semaphore rightFork = forks[(i + 1) % NUM_PHILOSOPHERS];
            philosophers[i] = new Philosopher(i, leftFork, rightFork);
            new Thread(philosophers[i], "Philosopher " + i).start();
        }
    }
}