diff --git a/bintree.c b/bintree.c
index 96b2b48..5f5fbbc 100644
--- a/bintree.c
+++ b/bintree.c
@@ -100,8 +100,12 @@ unsigned int treeSize(const TreeNode *root)
 
 int compareFct(const void *a, const void *b){
 
-	if(*a>*b)return -1;
-	if(*b>*a)return 1;
-	if(*a==*b)return 0;
+    unsigned int A = *(unsigned int *)a;
+    unsigned int B = *(unsigned int *)b;
+    int result= 0;
+	if(A>B)result = -1;  //logik vertauscht?
+	if(B>A)result = 1;  //logik vertauscht?
+	if(A==B)result = 0;
 
+    return result;
 }
\ No newline at end of file
diff --git a/bintree.h b/bintree.h
index 25e16b2..0fe9b44 100644
--- a/bintree.h
+++ b/bintree.h
@@ -24,4 +24,6 @@ void clearTree(TreeNode *root);
 // Returns the number of entries in the tree given by root.
 unsigned int treeSize(const TreeNode *root);
 
+int compareFct(const void *a, const void *b);
+
 #endif
\ No newline at end of file
diff --git a/numbers.c b/numbers.c
index b807838..5074138 100644
--- a/numbers.c
+++ b/numbers.c
@@ -19,33 +19,41 @@ unsigned int *createNumbers(unsigned int len)
 	srand(time(NULL));
 	unsigned int* numbers =malloc(sizeof(unsigned int) * len);
 	unsigned int numberTemp;
-	unsigned int* numbTempPtr = &numberTemp;
+	//unsigned int* numbTempPtr = &numberTemp;
 	int generated = 0;
 	int isDuplicate = 0;
 	TreeNode* root = NULL;
 
+    if(numbers == NULL)return NULL;
 
-	while(genreated<len){
 
-		numberTemp = (rand() % 2*len)+1;
-        root = addToTree( root, numbTempPtr, sizeof(unsigned int), compareFct, isDuplicate );
+	while(generated<len){
+
+		numberTemp = (rand() % (2*len))+1;
+
+	    isDuplicate = 0;
+
+        root = addToTree( root, &numberTemp, sizeof(unsigned int), compareFct, &isDuplicate );
 
         if(!isDuplicate){
 
-			numbers[genreated] = numberTemp;
-			genreated++;
+			numbers[generated] = numberTemp;
+			generated++;
 		}
 	}
 
 
 	int DuplicateId;
 	int DuplicatePlace;
-	do{
-	DuplicateId = rand()%len;
-	DuplicatePlace = rand() % len;
-	}while(DuplicateId != DuplicatePlace);
 
-	numbers[DuplicatePlace] = numbers[DuplicteId];
+	do{
+	DuplicateId = rand() % len;
+	DuplicatePlace = rand() % len;
+	}while(DuplicateId == DuplicatePlace);
+
+	numbers[DuplicatePlace] = numbers[DuplicateId];
+
+    clearTree(root);
 
 	return numbers;
 }
@@ -53,19 +61,21 @@ unsigned int *createNumbers(unsigned int len)
 // 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)
 {
-	unsigned int duplicate;
-    unsigned int duplicateId;
-	unsigned int duplicatePlace;
+    unsigned int duplicate = 0;
+    unsigned int* numbersCopy = malloc(sizeof(unsigned int) * len);
 
-	duplicateId = rand() % len;
-	duplicate = numbers[duplicateId];
+    if(numbersCopy == NULL)return 0;
 
-	do{
-		duplicatePlace = rand() % len;
 
-	}while(duplicatePlace == duplicateId);
+    memcpy(numbersCopy, numbers, sizeof(unsigned int) * len);
 
-	numbers[duplicatePlace] = duplicate;
+    qsort(numbersCopy, len, sizeof(unsigned int), compareFct);
+
+    for(int i=1; i<len; i++){
+        if(numbersCopy[i-1]==numbersCopy[i])duplicate = numbersCopy[i];
+    }
+
+    free(numbersCopy);
 
 	return duplicate;
 }
\ No newline at end of file
diff --git a/numbersTests.c b/numbersTests.c
index 97e9697..c51d343 100644
--- a/numbersTests.c
+++ b/numbersTests.c
@@ -1,12 +1,30 @@
 #include <stdio.h>
 #include "unity/unity.h"
 #include "numbers.h"
+#include <string.h>
 
 
 
 void setUp(void){}
 void tearDown(void){}
 
+void TEST_ZERO_DUPLICATE(){
+
+    unsigned int input[9] = {1,2,3,4,5,6,7,8,9};
+    TEST_ASSERT_EQUAL_INT(0, getDuplicate(input, 9));
+
+}
+
+
+void TEST_ONE_DUPLICATE(){
+
+    unsigned int input[9] = {1,2,3,4,5,6,7,2,9};
+    TEST_ASSERT_EQUAL_INT(2, getDuplicate(input, 9));
+
+}
+
+
+
 
 
 int main(){
@@ -14,9 +32,10 @@ int main(){
 
     printf("\n============================\nnumbers tests\n============================\n");
 
-    RUN_TEST(TEST_CREATE_STACK);
-    RUN_TEST(TEST_STACK_POP);
-    RUN_TEST(TEST_STACK_PUSH);
+    RUN_TEST(TEST_ZERO_DUPLICATE);
+    RUN_TEST(TEST_ONE_DUPLICATE);
+    //RUN_TEST();
 
     return UNITY_END();
-}
\ No newline at end of file
+}
+//Befehl zum Kompilieren: gcc numbers.h numbers.c numbersTests.c bintree.h bintree.c unity/unity.c
\ No newline at end of file