SemaphoreList.java

public class Semaphore {
    private int S;
    private Queue<Process> list; // Use a Queue to represent the process list

    public Semaphore(int permits) {
        this.S = permits;
        this.list = new LinkedList<>(); // Initialize the process list
    }
    
    public synchronized void P(Process process) { // "P" operation (wait/acquire)
        S--;
        if (S < 0) {
            list.add(process);  // Queue a process
            try {
                wait(); // Wait on the semaphore object
            } catch (InterruptedException e) {
                Thread.currentThread().interrupt();
            }
        }
    }

    public synchronized void V() { // "V" operation (signal/release)
        S++;
        if (S <= 0) { // There are waiting processes
            Process process = list.poll();
            if (process != null) {
                notify(); // Notify a waiting thread on the semaphore object
            }
        }
    }
}