From 4e98be1c07ad8b46470ec01bdf7a0f67eb074159 Mon Sep 17 00:00:00 2001
From: Oshgnacknak <osh@oshgnacknak.de>
Date: Fri, 3 Sep 2021 11:52:57 +0200
Subject: [PATCH] Implement max and secondMax

---
 ...cursiveOrderedBinaryTreeNodeProcessor.java | 40 ++++++++++++++--
 .../prep/tree/OrderedTreeProcessorTest.java   | 47 ++++++++++++++++---
 2 files changed, 77 insertions(+), 10 deletions(-)

diff --git a/src/aud/exam/prep/tree/RecursiveOrderedBinaryTreeNodeProcessor.java b/src/aud/exam/prep/tree/RecursiveOrderedBinaryTreeNodeProcessor.java
index 4fe012f..a6f643e 100644
--- a/src/aud/exam/prep/tree/RecursiveOrderedBinaryTreeNodeProcessor.java
+++ b/src/aud/exam/prep/tree/RecursiveOrderedBinaryTreeNodeProcessor.java
@@ -49,13 +49,45 @@ public class RecursiveOrderedBinaryTreeNodeProcessor<V> extends OrderedBinaryTre
     }
 
     @Override
-    public V max(BinaryTreeNode<V> tree, Comparator<V> cmp) {
-        return null;
+    public V max(BinaryTreeNode<V> tree) {
+        if (tree == null) {
+            throw new IllegalArgumentException("An empty tree has no max");
+        }
+
+        if (tree.right == null) {
+            return tree.key;
+        }
+
+        return max(tree.right);
     }
 
     @Override
-    public V secondMax(BinaryTreeNode<V> tree, Comparator<V> cmp) {
-        return null;
+    public V secondMax(BinaryTreeNode<V> tree) {
+        if (tree == null) {
+            throw new IllegalArgumentException("An empty tree has no second max");
+        }
+
+        if (tree.right != null) {
+            return secondMaxRec(tree.right, tree.key);
+        }
+
+        if (tree.left != null) {
+            return max(tree.left);
+        }
+
+        throw new IllegalArgumentException("A tree with only one element has no second max");
+    }
+
+    private V secondMaxRec(BinaryTreeNode<V> node, V prev) {
+        if (node.right != null) {
+            return secondMaxRec(node.right, node.key);
+        }
+
+        if (node.left != null) {
+            return max(node.left);
+        }
+
+        return prev;
     }
 
     @Override
diff --git a/test/aud/exam/prep/tree/OrderedTreeProcessorTest.java b/test/aud/exam/prep/tree/OrderedTreeProcessorTest.java
index 5504803..bd1ea35 100644
--- a/test/aud/exam/prep/tree/OrderedTreeProcessorTest.java
+++ b/test/aud/exam/prep/tree/OrderedTreeProcessorTest.java
@@ -1,7 +1,7 @@
 package aud.exam.prep.tree;
 
 import aud.exam.prep.ListProvider;
-import aud.exam.prep.tree.OrderedTreeProcessor;
+import aud.exam.prep.Tests;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.ArgumentsSource;
@@ -42,14 +42,49 @@ public abstract class OrderedTreeProcessorTest<T> {
     @ParameterizedTest
     @ArgumentsSource(ListProvider.class)
     void testThat_insertAndIterateWork(List<Integer> list) {
-        T t = processor.newEmptyTree();
-
-        for (var n : list) {
-            t = processor.insert(t, n, CMP);
-        }
+        T t = asTree(list);
         list.sort(CMP);
 
         assertTrue(processor.check(t, CMP));
         assertIterableEquals(list, processor.iterate(t));
     }
+
+    private T asTree(List<Integer> list) {
+        T t = processor.newEmptyTree();
+
+        for (var n : list) {
+            t = processor.insert(t, n, CMP);
+        }
+
+        return t;
+    }
+
+    @ParameterizedTest
+    @ArgumentsSource(ListProvider.class)
+    void testThat_maxWorks(List<Integer> list) {
+        list.add(-1);
+        T t = asTree(list);
+
+        Integer max = Tests.getMax(list);
+        assertEquals(max, processor.max(t));
+    }
+
+    @ParameterizedTest
+    @ArgumentsSource(ListProvider.class)
+    void testThat_secondMaxWorks(List<Integer> list) {
+        list.add(-1);
+        list.add(-2);
+        T t = asTree(list);
+
+        Integer max = Tests.getSecondMax(list);
+        assertEquals(max, processor.secondMax(t));
+    }
+
+
+    @ParameterizedTest
+    @ArgumentsSource(ListProvider.class)
+    void printATree(List<Integer> list) {
+        T t = asTree(list);
+        processor.print(t);
+    }
 }
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