solved

src/main/java/mate/academy/TicketBookingSystem.java

@@ -1,12 +1,17 @@
 package mate.academy;
 
+import java.util.concurrent.Semaphore;
+
 public class TicketBookingSystem {
+    private final Semaphore semaphore;
 
     public TicketBookingSystem(int totalSeats) {
-
+        this.semaphore = new Semaphore(totalSeats);
     }
 
     public BookingResult attemptBooking(String user) {
-        return null;
+        boolean success = semaphore.tryAcquire();
+        return new BookingResult(user, success,
+                success ? "Booking successful." : "No seats available.");
     }
 }