Implement clone and invert

src/aud/exam/prep/tree/OrderedTreeProcessor.java

@@ -43,7 +43,7 @@ public interface OrderedTreeProcessor<V, T> {
 
     T leftmostNodeInRightSubtree(T t);
 
-    T invert(T t);
+    void invert(T t);
 
     T clone(T t);
 

src/aud/exam/prep/tree/RecursiveOrderedBinaryTreeNodeProcessor.java

@@ -300,15 +300,33 @@ public class RecursiveOrderedBinaryTreeNodeProcessor<V> extends OrderedBinaryTre
     }
 
     @Override
-    public BinaryTreeNode<V> invert(BinaryTreeNode<V> tree) {
+    public void invert(BinaryTreeNode<V> tree) {
-        return null;
+        if (tree == null) {
+            return;
+        }
+
+        invert(tree.left);
+        invert(tree.right);
+
+        var t = tree.left;
+        tree.left = tree.right;
+        tree.right = t;
     }
 
     @Override
     public BinaryTreeNode<V> clone(BinaryTreeNode<V> tree) {
+        if (tree == null) {
             return null;
         }
 
+        var t = new BinaryTreeNode<V>();
+        t.left = clone(tree.left);
+        t.right = clone(tree.right);
+        t.key = tree.key;
+
+        return t;
+    }
+
     @Override
     public boolean check(BinaryTreeNode<V> tree, Comparator<V> cmp) {
         if (tree == null) {

test/aud/exam/prep/tree/OrderedTreeProcessorTest.java

@@ -243,4 +243,28 @@ public abstract class OrderedTreeProcessorTest<T> {
             assertIterableEquals(list, processor.iterate(t));
         }
     }
+
+    @ParameterizedTest
+    @ArgumentsSource(ListProvider.class)
+    void testThat_invertWorks(List<Integer> list) {
+        T t = asTree(list);
+        processor.invert(t);
+
+        var cmp = CMP.reversed();
+
+        assertTrue(processor.check(t, cmp));
+        list.sort(cmp);
+        assertIterableEquals(list, processor.iterate(t));
+    }
+
+    @ParameterizedTest
+    @ArgumentsSource(ListProvider.class)
+    void testThat_cloneWorks(List<Integer> list) {
+        T t = asTree(list);
+        t = processor.clone(t);
+
+        assertTrue(processor.check(t, CMP));
+        list.sort(CMP);
+        assertIterableEquals(list, processor.iterate(t));
+    }
 }