diff --git a/bintree.c b/bintree.c
index b1cf8f5..ddc57bb 100644
--- a/bintree.c
+++ b/bintree.c
@@ -51,9 +51,34 @@ TreeNode *addToTree(TreeNode *root, const void *data, size_t dataSize,
 // Iterates over the tree given by root. Follows the usage of strtok. If tree is NULL, the next entry of the last tree given is returned in ordering direction.
 // Use your implementation of a stack to organize the iterator. Push the root node and all left nodes first. On returning the next element,
 // push the top node and push all its left nodes.
-void *nextTreeData(TreeNode *root)
-{
+// Initialisiert den Stack mit der Wurzel und allen linken Nachfolgern
+StackNode* initTraversal(TreeNode* root) {
+    StackNode* stack = NULL;
+    TreeNode* current = root;
 
+    while (current != NULL) {
+        stack = push(stack, current);
+        current = current->left;
+    }
+    return stack;
+}
+void* nextTreeData(StackNode** stack) {
+    if (*stack == NULL) {
+        return NULL; // Traversierung beendet
+    }
+
+    // Obersten Knoten holen
+    TreeNode* node = (TreeNode*)top(*stack);
+    *stack = pop(*stack);
+
+    // Falls rechter Teilbaum existiert, diesen und alle linken Nachfolger auf den Stack legen
+    TreeNode* current = node->right;
+    while (current != NULL) {
+        *stack = push(*stack, current);
+        current = current->left;
+    }
+
+    return node->data;
 }
 
 // Releases all memory resources (including data copies).
@@ -75,5 +100,9 @@ void clearTree(TreeNode *root)
 // Returns the number of entries in the tree given by root.
 unsigned int treeSize(const TreeNode *root)
 {
-
+ if (root == NULL) {
+        return 0; // Basisfall: leerer Teilbaum
+    }
+    // Rekursiv: Größe = 1 (aktueller Knoten) + Größe des linken Teilbaums + Größe des rechten Teilbaums
+    return 1 + treeSize(root->left) + treeSize(root->right);
 }
\ No newline at end of file