diff --git a/numbers.c b/numbers.c
index f59d9a2..9c46779 100644
--- a/numbers.c
+++ b/numbers.c
@@ -16,11 +16,49 @@
 // creating random numbers.
 unsigned int *createNumbers(unsigned int len)
 {
-
+  //Idee: Array mit while Schleife in Binaerbaum eintragen, dann Baum traversieren, um zu schauen, ob Element doppelt ist
+  srand(time(NULL));
+  if(len>0)
+    {
+    unsigned int random;
+    int *duplicate = 0;
+    unsigned int *numbers = (unsigned int *)malloc(sizeof(unsigned int) * len); //erstellt ein Array mit der Laenge von len, ALternative: sizeofTree verwenden, um Groeße Array zu bestimmen
+    if(numbers == NULL)
+      return NULL;
+      for(unsigned int i=0;i<len;i++)
+      {
+        random = rand()%(2*len - 1) - 1;
+        TreeNode *newNode = (TreeNode *)malloc(sizeof(TreeNode));
+        if(addToTree(newNode, random, sizeof(random), compareFct, duplicate)) //wenn newNode zum Tree hinzugefuegt werden konnte,
+                                                                              // also wenn max. ein Duplikat vorhanden ist im Baum, fuege newNode zu Array hinzu
+          {
+            numbers[i] = random;
+          }
+      }
+    clearTree(newNode);
+    return numbers;
+    }
+  return NULL;
 }
 
 // Returns only the only number in numbers which is present twice. Returns zero on errors.
 unsigned int getDuplicate(const unsigned int numbers[], unsigned int len)
 {
-
+  if(len>0)
+    {
+    unsigned int duplicate = 0;
+    for(unsigned int i=0;i<len;i++)
+      {
+        unsigned int v1 = numbers[i];
+        for(unsigned int j=i+1;j<len;j++)
+          {
+          unsigned int v2 = numbers[j];
+          if(v1==v2)
+            {
+            return v1;
+            }
+          }
+      }
+    }
+  return 0;
 }
\ No newline at end of file
diff --git a/stack.c b/stack.c
index d44de95..764a080 100644
--- a/stack.c
+++ b/stack.c
@@ -51,7 +51,7 @@ void clearStack(StackNode *stack)
   while(stack)
   {
       StackNode *tmp = stack;
-      stack = stack->prev;
+      stack = stack->next;
       free(tmp->data);
       free(tmp);
   }