uebung_03: implement Task 3 (BST) and Task 4 (IntHashSet)

Task 3 adds IntBinarySearchTree with iterative add/contains and a
test class covering empty trees, duplicates, and degenerate ascending
and descending insertion orders.

Task 4 adds IntHashSet backed by an IntLinkedList bucket array with
a 0.7 load factor, Math.floorMod-based hashing for negative-int
safety, doubling resize that rehashes via a private
addWithoutResize helper, and a test class covering negatives,
Integer.MIN_VALUE, forced collisions on bucket 0, and 100-element
inserts spanning three resizes.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

uebung_03/src/IntBinarySearchTree.java

@@ -0,0 +1,54 @@
+public class IntBinarySearchTree {
+    IntTreeNode root;
+
+    public IntBinarySearchTree(){
+    }
+
+    public void add(int value){
+        if (root == null){
+            root = new IntTreeNode(value);
+            return;
+        }
+
+        IntTreeNode currentRelativRoot = root;
+        while (true) {
+            if(value == currentRelativRoot.value){
+                return;
+            }
+            if (value < currentRelativRoot.value) {
+                if (currentRelativRoot.left == null) {
+                    currentRelativRoot.left = new IntTreeNode(value);
+                    return;
+                } else currentRelativRoot = currentRelativRoot.left;
+
+            } else {
+                if (currentRelativRoot.right == null) {
+                    currentRelativRoot.right = new IntTreeNode(value);
+                    return;
+                } else currentRelativRoot = currentRelativRoot.right;
+
+            }
+        }
+    }
+    public boolean contains(int value){
+        if (root == null) return false;
+        IntTreeNode currentRelativRoot = root;
+        while (true){
+            if(value == currentRelativRoot.value){
+                return true;
+            }
+            if (value < currentRelativRoot.value) {
+                if (currentRelativRoot.left == null) {
+                    return false;
+                } else currentRelativRoot = currentRelativRoot.left;
+
+            } else {
+                if (currentRelativRoot.right == null) {
+                    return false;
+                } else currentRelativRoot = currentRelativRoot.right;
+
+            }
+        }
+
+    }
+}