diff --git a/bintree.c b/bintree.c
index 14632fa..42d1118 100644
--- a/bintree.c
+++ b/bintree.c
@@ -13,34 +13,50 @@
 //  ordering. Accepts duplicates if isDuplicate is NULL, otherwise ignores
 //  duplicates and sets isDuplicate to 1 (or to 0 if a new entry is added).
 
+TreeNode *createTreeNode(const void *data, size_t dataSize) {
+  TreeNode *node =
+      malloc(sizeof(TreeNode)); // Speicher für neuen Knoten reservieren
+  if (node == NULL)
+    return NULL; // Abbrechen bei Fehler
+
+  node->data = malloc(dataSize); // Speicher für Daten reservieren
+  if (node->data == NULL) {
+    free(node);
+    return NULL;
+  }
+
+  memcpy(node->data, data, dataSize); // Standardfunktion string.h, kopiert
+                                      // size bytes von data nach node->data,
+                                      // daten dürfen sich nicht überschneiden
+                                      // speichern der Daten in node->data
+  node->left = NULL;                  // Kinder sind NULL
+  node->right = NULL;
+  return node;
+}
+
 TreeNode *addToTree(TreeNode *root, const void *data, size_t dataSize,
                     CompareFctType compareFct, int *isDuplicate) {
 
-  // isDuplicate initialisieren (auf 0 setzen)
+  // isDuplicate initialisieren (auf 0 setzen), verhindert Änderung am Baum
   if (isDuplicate) {
     *isDuplicate = 0;
-  }
+  } // bei 0: neuer Wert wurde eingefügt, bei 1: Wert war bereits im Baum
 
   // leerer Baum
   if (root == NULL) {
-    TreeNode *node = malloc(sizeof(TreeNode));
-    node->data = malloc(dataSize);
-    memcpy(node->data, data, dataSize);
-    node->left = NULL;
-    node->right = NULL;
-    return node;
+    return createTreeNode(data, dataSize);
   }
 
   // mit compareFct <0 links >0 rechts =0 Duplikat
-  int cmp = compareFct(data, root->data);
+  int compare = compareFct(data, root->data);
 
-  if (cmp < 0) {
+  if (compare < 0) { // Eintrag links
     root->left = addToTree(root->left, data, dataSize, compareFct, isDuplicate);
-  } else if (cmp > 0) {
+  } else if (compare > 0) { // Eintrag rechts
     root->right =
         addToTree(root->right, data, dataSize, compareFct, isDuplicate);
-  } else {
-    // isDuplicate auf 1 setzen
+  } else { // Duplikat
+    // isDuplicate auf 1 setzen, keine Änderung am Baum
     if (isDuplicate) {
       *isDuplicate = 1;
     }
@@ -54,40 +70,42 @@ TreeNode *addToTree(TreeNode *root, const void *data, size_t dataSize,
 // 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) {
-  static StackNode *stack = NULL;
+  static StackNode *stack = NULL; // static -> behält Wert bei mehreren Aufrufen
 
   // Neue Iteration starten
   if (root != NULL) {
-    clearStack(&stack);
+    clearStack(&stack); // alte Stack-Inhalte werden gelöscht
 
-    TreeNode *curr = root;
-    while (curr != NULL) {
+    TreeNode *currentNode = root;
+    while (currentNode !=
+           NULL) { // alle linken Knoten werden vom root an auf den Stack gelegt
       StackNode *oldStack = stack;
-      StackNode *newStack = push(stack, curr);
+      StackNode *newStack = push(stack, currentNode);
       if (newStack == oldStack)
         return NULL; // push fehlgeschlagen
       stack = newStack;
-      curr = curr->left;
+      currentNode = currentNode->left;
     }
   }
   if (stack == NULL)
-    return NULL; // alles durchlaufen
+    return NULL; // wenn Stack leer ist sind keine Elemente mehr vorhanden,
+                 // Iteration beendet
 
-  // Oberstes Element abrufen
-  TreeNode *node = (TreeNode *)top(stack);
+  // oberster Knoten vom Stack
+  TreeNode *node = top(stack);
   stack = pop(stack);
 
   // Rechten Teilbaum pushen
-  TreeNode *curr = node->right;
-  while (curr != NULL) {
+  TreeNode *currentNode = node->right;
+  while (currentNode != NULL) {
     StackNode *oldStack = stack;
-    StackNode *newStack = push(stack, curr);
+    StackNode *newStack = push(stack, currentNode);
     if (newStack == oldStack)
       return NULL; // push fehlgeschlagen
     stack = newStack;
-    curr = curr->left;
+    currentNode = currentNode->left;
   }
-  return node->data;
+  return node->data; // Pointer auf Daten
 }
 
 // Releases all memory resources (including data copies).
diff --git a/bintree.h b/bintree.h
index 9e6b45c..aeb72ed 100644
--- a/bintree.h
+++ b/bintree.h
@@ -11,6 +11,8 @@ typedef struct node {
   struct node *right;
 } TreeNode;
 
+TreeNode *createTreeNode(const void *data, size_t dataSize);
+
 // Adds a copy of data's pointer destination to the tree using compareFct for
 // ordering. Accepts duplicates if isDuplicate is NULL, otherwise ignores
 // duplicates and sets isDuplicate to 1 (or to 0 if a new entry is added).
diff --git a/highscores.txt b/highscores.txt
index aaac161..bda4db4 100644
--- a/highscores.txt
+++ b/highscores.txt
@@ -1,10 +1,10 @@
 Kristin;49209
-Kristin;9959
-Kristin;9944
-Kristin;7947
-Kristin;6962
-Kristin;5987
-Kristin;5975
-krisp;4986
-krisp;4985
-Kristin;4972
+krisp;29797
+krisp;29792
+Kristin;29782
+Kristin;19943
+krisp;19934
+krisp;19916
+kristin;19861
+Kristin;19858
+krisp;19460
diff --git a/main.c b/main.c
index 34163d0..1dd21cf 100644
--- a/main.c
+++ b/main.c
@@ -1,90 +1,88 @@
-#include <stdlib.h>
-#include <stdio.h>
+#include "highscore.h"
 #include "numbers.h"
 #include "timer.h"
-#include "highscore.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
 
 // Read an unsigned integer from stdin with prompt (retries until valid).
-int inputNumber(const char *promptText)
-{
-    unsigned int number;
-    int numberOfInputs = 0;
+int inputNumber(const char *promptText) {
+  unsigned int number;
+  int numberOfInputs = 0;
 
-    while(numberOfInputs != 1)
-    {
-        printf("%s", promptText);
-        numberOfInputs = scanf("%u", &number);
-        while(getchar() != '\n') {} // clear input buffer
-    }
+  while (numberOfInputs != 1) {
+    printf("%s", promptText);
+    numberOfInputs = scanf("%u", &number);
+    while (getchar() != '\n') {
+    } // clear input buffer
+  }
 
-    return number;
+  return number;
 }
 
 // Print an array of numbers.
-void showNumbers(const unsigned int *numbers, unsigned int len)
-{
-    if(numbers != NULL)
-    {
-        printf("Numbers:");
+void showNumbers(const unsigned int *numbers, unsigned int len) {
+  if (numbers != NULL) {
+    printf("Numbers:");
 
-        for(int i = 0; i < len; i++)
-            printf(" %5d", numbers[i]);
+    for (int i = 0; i < len; i++)
+      printf(" %5d", numbers[i]);
 
-        printf("\n");
-    }
+    printf("\n");
+  }
 }
 
-// Main game loop: generate numbers, ask user for duplicate, measure time, update highscores.
-int main(int argc, char *argv[])
-{
-    int exitCode = EXIT_FAILURE;
+// Main game loop: generate numbers, ask user for duplicate, measure time,
+// update highscores.
+int main(int argc, char *argv[]) {
+  srand(time(NULL)); // seed für srand
+  int exitCode = EXIT_FAILURE;
 
-    if(argc != 2)
-    {
-        fprintf(stderr, "Usage: %s <player name>\n", argv[0]);
-        exitCode = EXIT_FAILURE;
-    }
-    else
-    {
-        const char *highscorePath = "highscores.txt";
-        const char *playerName = argv[1];
-        unsigned int *numbers = NULL;
-        unsigned int duplicate = 0;
-        double measuredSeconds;
-        unsigned int userInput;
-        unsigned int numberOfElements = 0;
+  if (argc != 2) {
+    fprintf(stderr, "Usage: %s <player name>\n", argv[0]);
+    exitCode = EXIT_FAILURE;
+  } else {
+    const char *highscorePath = "highscores.txt";
+    const char *playerName = argv[1];
+    unsigned int *numbers = NULL;
+    unsigned int duplicate = 0;
+    double measuredSeconds;
+    unsigned int userInput;
+    unsigned int numberOfElements = 0;
 
-        // ask until valid number of elements (3..1000)
-        while(numberOfElements < 3 || numberOfElements > 1000)
-            numberOfElements = inputNumber("Wie viele Zahlen sollen gezeigt werden: ");
+    // ask until valid number of elements (3..1000)
+    while (numberOfElements < 3 || numberOfElements > 1000)
+      numberOfElements =
+          inputNumber("Wie viele Zahlen sollen gezeigt werden: ");
 
-        // create numbers and show them
-        numbers = createNumbers(numberOfElements);
-        showNumbers(numbers, numberOfElements);
+    // create numbers and show them
+    numbers = createNumbers(numberOfElements);
+    showNumbers(numbers, numberOfElements);
 
-        // measure time while user guesses the duplicate
-        startTimer();
-        userInput = inputNumber("Welche Zahl kommt doppelt vor: ");
-        measuredSeconds = stopTimer();
+    // measure time while user guesses the duplicate
+    startTimer();
+    userInput = inputNumber("Welche Zahl kommt doppelt vor: ");
+    measuredSeconds = stopTimer();
 
-        duplicate = getDuplicate(numbers, numberOfElements);
+    duplicate = getDuplicate(numbers, numberOfElements);
 
-        // check result and update highscores
-        if(userInput == duplicate)
-        {
-            int score = addHighscore(playerName, measuredSeconds, numberOfElements);
-            printf("Sie haben die korrekte Zahl in %.6lf Sekunde(n) gefunden und %u Punkte erzielt.\n", measuredSeconds, score);
-        }
-        else
-            printf("Leider ist %u nicht korrekt. Richtig waere %u gewesen.\n", userInput, duplicate);
+    // check result and update highscores
+    if (userInput == duplicate) {
+      int score = addHighscore(playerName, measuredSeconds, numberOfElements);
+      printf("Sie haben die korrekte Zahl in %.6lf Sekunde(n) gefunden und %u "
+             "Punkte erzielt.\n",
+             measuredSeconds, score);
+    } else
+      printf("Leider ist %u nicht korrekt. Richtig waere %u gewesen.\n",
+             userInput, duplicate);
 
-        loadHighscores(highscorePath);
-        showHighscores();
-        saveHighscores(highscorePath);
-        clearHighscores();
+    loadHighscores(highscorePath);
+    showHighscores();
+    saveHighscores(highscorePath);
+    clearHighscores();
 
-        exitCode = EXIT_SUCCESS;
-    }
+    exitCode = EXIT_SUCCESS;
+  }
 
-    return exitCode;
+  return exitCode;
 }
\ No newline at end of file
diff --git a/numbers.c b/numbers.c
index 414a4a4..5c2f30a 100644
--- a/numbers.c
+++ b/numbers.c
@@ -3,18 +3,6 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#include <time.h>
-
-int compareUnsignedInt(const void *a, const void *b) {
-  unsigned int x = *(unsigned int *)a;
-  unsigned int y = *(unsigned int *)b;
-
-  if (x < y)
-    return -1;
-  if (x > y)
-    return 1;
-  return 0;
-}
 
 // TODO: getDuplicate und createNumbers implementieren
 /**Erzeugen eines Arrays mit der vom Nutzer eingegebenen Anzahl an
@@ -27,65 +15,77 @@ int compareUnsignedInt(const void *a, const void *b) {
 // different, except for two entries. Returns NULL on errors. Use your
 // implementation of the binary search tree to check for possible duplicates
 // while creating random numbers.
+
+// vergleicht zwei Werte: a<b: -1 a>b: 1 a=b: 0
+int compareUnsignedInt(const void *a, const void *b) {
+  unsigned int x = *(unsigned int *)a;
+  unsigned int y = *(unsigned int *)b;
+  return (x < y) ? -1 : (x > y);
+}
+
 unsigned int *createNumbers(unsigned int len) {
-  if (len < 2)
+  if (len < 2) // Duplikat bei zwei Einträgen sinnlos
     return NULL;
 
-  unsigned int *arr = malloc(sizeof(unsigned int) * len);
-  if (!arr)
+  unsigned int *numbersArray = malloc(
+      sizeof(unsigned int) * len); // Speicher für das Ausgabearray reservieren:
+                                   // Größe eines Eintrags * Größe des Arrays
+  if (!numbersArray)               // Speicher konnte nicht reserviert werden
     return NULL;
 
-  TreeNode *root = NULL;
-  srand((unsigned int)time(NULL));
+  TreeNode *root =
+      NULL; // Binärbaum zum Generieren der Zufallszahlen ohne Duplikate
 
-  for (unsigned int i = 0; i < len - 1; i++) {
-    unsigned int num;
+  for (unsigned int i = 0; i < len; i++) {
+    unsigned int currentNumber;
     int isDuplicate;
-
-    do {
-      num = (rand() % (2 * len)) + 1;
+    do { // mindestens eine Zufallszahl erzeugen
+      currentNumber = (rand() % (2 * len)) + 1; // Zahlenbereich 1 bis 2*len
       isDuplicate = 0;
-
-      root = addToTree(root, &num, sizeof(unsigned int), compareUnsignedInt,
-                       &isDuplicate);
-
-    } while (isDuplicate); // nur akzeptieren, wenn eindeutig
-
-    arr[i] = num;
+      root = addToTree(root, &currentNumber, sizeof(unsigned int),
+                       compareUnsignedInt,
+                       &isDuplicate); // compareUnsignedInt wird zum Verwenden
+                                      // bei Vergleichen übergeben
+    } while (isDuplicate); // wenn isDuplicate gesetzt wird, muss eine neue Zahl
+                           // erzeugt werden, die Schleife wird wiederholt
+    numbersArray[i] = currentNumber;
   }
 
-  // Jetzt gezielt EIN Duplikat erzeugen
-  unsigned int duplicateIndex = rand() % (len - 1);
-  arr[len - 1] = arr[duplicateIndex];
+  // Ein zufälliges Duplikat erzeugen
+  unsigned int duplicateIndex =
+      rand() % len; // Index des Duplikats per Zufall bestimmen
+  unsigned int newIndex;
+  do {
+    newIndex = rand() % len;
+  } while (newIndex == duplicateIndex); // zweiten Index bestimmen, der nicht
+                                        // mit dem ersten übereinstimmt
 
-  clearTree(root);
-  return arr;
+  numbersArray[newIndex] =
+      numbersArray[duplicateIndex]; // Wert vom ersten Index kopieren
+
+  clearTree(root); // Speicher wieder freigeben, wird nicht mehr benötigt
+  return numbersArray;
 }
 
 // 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 getDuplicate(const unsigned int *numbers, unsigned int len) {
   if (!numbers || len < 2)
-    return 0;
+    return NULL; // Fehlerhaftes Array
 
-  unsigned int *copy = malloc(sizeof(unsigned int) * len);
-  if (!copy)
-    return 0;
+  TreeNode *root = NULL; // neuer Baum
+  unsigned int duplicateValue = 0;
 
-  memcpy(copy, numbers, sizeof(unsigned int) * len);
-
-  // Sortierung
-  qsort(copy, len, sizeof(unsigned int), compareUnsignedInt);
-
-  // Duplikat finden: zwei gleiche nebeneinander
-  unsigned int duplicate = 0;
-  for (unsigned int i = 0; i < len - 1; i++) {
-    if (copy[i] == copy[i + 1]) {
-      duplicate = copy[i];
+  for (unsigned int i = 0; i < len; i++) {
+    int isDuplicate = 0;
+    root = addToTree(root, &numbers[i], sizeof(unsigned int),
+                     compareUnsignedInt, &isDuplicate);
+    if (isDuplicate) {
+      duplicateValue = numbers[i];
       break;
     }
   }
 
-  free(copy);
-  return duplicate;
+  clearTree(root);
+  return duplicateValue;
 }
diff --git a/numbers.h b/numbers.h
index 2315581..6708308 100644
--- a/numbers.h
+++ b/numbers.h
@@ -1,12 +1,16 @@
 #ifndef NUMBERS_H
 #define NUMBERS_H
 
-// Returns len random numbers between 1 and 2x len in random order which are all different, except for two entries.
-// Returns NULL on errors. Use your implementation of the binary search tree to check for possible duplicates while
-// creating random numbers.
+int compareUnsignedInt(const void *a, const void *b);
+
+// Returns len random numbers between 1 and 2x len in random order which are all
+// different, except for two entries. Returns NULL on errors. Use your
+// implementation of the binary search tree to check for possible duplicates
+// while creating random numbers.
 unsigned int *createNumbers(unsigned int len);
 
-// Returns only the only number in numbers which is present twice. Returns zero on errors.
+// 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);
 
 #endif
\ No newline at end of file
diff --git a/test_binary.c b/test_binary.c
index a0d9cbc..c7aca72 100644
--- a/test_binary.c
+++ b/test_binary.c
@@ -4,6 +4,7 @@
 #include <string.h>
 
 #include "bintree.h"
+
 int compareUnsignedInt(const void *a, const void *b) {
   unsigned int x = *(unsigned int *)a;
   unsigned int y = *(unsigned int *)b;