class PriorityQueue { private class Node { private Base object; private int rank; private Node left; private Node right; private Node(Base object, int rank) { this.object = object; this.rank = rank; left = null; right = null; } } private Node root; // Root node of the BST. public PriorityQueue() { root = new Node(null, -1); } //root is the One God public boolean isEmpty() { return root.right==root.left; } public Base dequeue() { if (isEmpty()) { throw new IllegalStateException(); } else { Node Test = root; return Test.object; } } // Unlike the BST’s discussed in the lectures, the nodes in //each left subtree have ranks less than or equal to the // rank at the root. The nodes in each right subtree have // ranks greater than the rank at the root. // This allows two or more nodes to have the same rank. public void enqueue(Base object, int rank) { if (rank < 0) { throw new IllegalArgumentException(); } else { } } } // SNOBBERY. How the aristocracy behaves in a queue. 20 points. class Snobbery { // MAIN. Queue them up. public static void main(String[] args) { PriorityQueue queue = new PriorityQueue(); System.out.println(queue.isEmpty()); // true 2 points try { System.out.println(queue.dequeue()); } catch (IllegalStateException ignore) { System.out.println("Blimey!"); // Blimey! 2 points } queue.enqueue("Lancelot", 5); queue.enqueue("Fawlty", 7); queue.enqueue("Elizabeth", 0); queue.enqueue("Charles", 1); queue.enqueue("Turing", 7); try { queue.enqueue("Zeus", -100); } catch (IllegalArgumentException ignore) { System.out.println("No gods!"); // No gods! 2 points } System.out.println(queue.isEmpty()); // false 2 points System.out.println(queue.dequeue()); // Elizabeth 2 points System.out.println(queue.dequeue()); // Charles 2 points System.out.println(queue.dequeue()); // Lancelot 2 points System.out.println(queue.dequeue()); // Turing 2 points System.out.println(queue.dequeue()); // Fawlty 2 points // It's OK if Fawlty comes out before Turing, but both must come out last. System.out.println(queue.isEmpty()); // true 2 points. } }