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/IntHashSet.java

@@ -0,0 +1,81 @@
+public class IntHashSet {
+    private IntLinkedList[] buckets;
+    private int size;
+
+    private int capacity;
+
+     private static final double LOAD_PERCENT = 0.7;
+
+    public IntHashSet(){
+        buckets = new IntLinkedList[16];
+        capacity = 16;
+    }
+
+    private int hash(int value){
+        return Math.floorMod(value, capacity);
+    }
+    private boolean loadReached(){
+        return (double) size / capacity >= LOAD_PERCENT;
+    }
+
+    private void resize(){
+        IntLinkedList[] oldBuckets = buckets;
+        capacity *=2;
+        buckets = new IntLinkedList[capacity];
+        size = 0;
+        for (IntLinkedList oldBucket : oldBuckets) {
+            if (oldBucket == null) continue;
+            for (int j = 0; j < oldBucket.getSize(); j++) {
+                addWithoutResize(oldBucket.get(j));
+            }
+        }
+    }
+
+
+    public void add(int value){
+        int index = hash(value);
+        if (buckets[index] == null){
+            buckets[index] = new IntLinkedList();
+            buckets[index].add(value);
+            size++;
+            if (loadReached()) resize();
+            return;
+        }
+        for (int i = 0; i < buckets[index].getSize(); i++){
+            if (buckets[index].get(i) == value){
+                return;
+            }
+        }
+        buckets[index].add(value);
+        size++;
+        if (loadReached()) resize();
+    }
+    private void addWithoutResize(int value){
+        int index = hash(value);
+        if (buckets[index] == null){
+            buckets[index] = new IntLinkedList();
+            buckets[index].add(value);
+            size++;
+            return;
+        }
+        for (int i = 0; i < buckets[index].getSize(); i++){
+            if (buckets[index].get(i) == value){
+                return;
+            }
+        }
+        buckets[index].add(value);
+        size++;
+    }
+    public boolean contains(int value){
+        int index = hash(value);
+        if (buckets[index] == null){
+            return false;
+        }
+        for (int i = 0; i < buckets[index].getSize(); i++){
+            if (buckets[index].get(i) == value){
+                return true;
+            }
+        }
+        return false;
+    }
+}