remove vla

bintree.c

@@ -1,8 +1,9 @@
 #include <string.h>
 #include "stack.h"
 #include "bintree.h"
+#include <stdlib.h>
 
-//TODO: binären Suchbaum implementieren
+// TODO: binären Suchbaum implementieren
 /*  * `addToTree`: fügt ein neues Element in den Baum ein (rekursiv),
  * `clearTree`: gibt den gesamten Baum frei (rekursiv),
  * `treeSize`: zählt die Knoten im Baum (rekursiv),
@@ -12,7 +13,70 @@
 // if isDuplicate is NULL, otherwise ignores duplicates and sets isDuplicate to 1 (or to 0 if a new entry is added).
 TreeNode *addToTree(TreeNode *root, const void *data, size_t dataSize, CompareFctType compareFct, int *isDuplicate)
 {
+    TreeNode *insertedNode;
 
+    // create a new node if the current node is NULL
+    if (root == NULL)
+    {
+        // it's important to zero the pointers for adjacent nodes
+        insertedNode = calloc(1, sizeof(TreeNode));
+        if (!insertedNode)
+        {
+            return NULL;
+        }
+
+        insertedNode->data = malloc(dataSize);
+        if (!insertedNode->data)
+        {
+            return NULL;
+        }
+        memcpy(insertedNode->data, data, dataSize);
+        // reset isDuplicate if it exists
+        if (isDuplicate)
+        {
+            *isDuplicate = 0;
+        }
+        return insertedNode;
+    }
+
+    // TODO: what is the correct data type here?
+    int cmpRes = (*compareFct)(data, root->data);
+    // insert into the left branch
+    if (cmpRes < 0 || (cmpRes == 0 && isDuplicate == NULL))
+    {
+        root->left = addToTree(root->left, data, dataSize, compareFct, isDuplicate);
+    }
+    // insert into the right branch
+    else if (cmpRes > 0)
+    {
+        root->right = addToTree(root->right, data, dataSize, compareFct, isDuplicate);
+    }
+    // the data is equal to the current node
+    else
+    {
+        // the data already exists in the tree and duplicates are ignored (isDuplicate* not NULL)
+        *isDuplicate = 1;
+    }
+    return root;
+}
+
+// push all left descendants from @param node
+static void pushLeftDesc(StackNode **stackPtr, TreeNode *node)
+{
+    if (!stackPtr || !node)
+    {
+        return;
+    }
+    TreeNode *curNode = node;
+    while (curNode->left)
+    {
+        *stackPtr = push(*stackPtr, curNode->left);
+        if (!*stackPtr)
+        {
+            return;
+        }
+        curNode = curNode->left;
+    }
 }
 
 // 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.
@@ -20,17 +84,72 @@ TreeNode *addToTree(TreeNode *root, const void *data, size_t dataSize, CompareFc
 // push the top node and push all its left nodes.
 void *nextTreeData(TreeNode *root)
 {
+    // this creates a static variable that maintains an internal state
+    static StackNode *stack;
 
+    // create a new stack
+    if (root)
+    {
+        // clear possibly existing stacks
+        clearStack(stack);
+        // init a new stack
+        stack = push(NULL, root);
+        // init failed
+        if (!stack)
+        {
+            return NULL;
+        }
+        pushLeftDesc(&stack, root);
+
+        // return the first val
+        return nextTreeData(NULL);
+    }
+
+    // neither stack nor root exist
+    if (!stack)
+    {
+        return NULL;
+    }
+
+    // get next val with stack
+    TreeNode *res = top(stack);
+    stack = pop(stack);
+    if (res->right)
+    {
+        stack = push(stack, res->right);
+        pushLeftDesc(&stack, res->right);
+    }
+
+    return res->data;
 }
 
 // Releases all memory resources (including data copies).
 void clearTree(TreeNode *root)
 {
+    // this check is crucial for recursion
+    if (!root)
+    {
+        // nothing to clear
+        return;
+    }
 
+    // release the resources of child nodes first
+    clearTree(root->left);
+    clearTree(root->right);
+
+    // free the data (it's just a copy created in addToTree())
+    free(root->data);
+    free(root);
 }
 
 // Returns the number of entries in the tree given by root.
 unsigned int treeSize(const TreeNode *root)
 {
+    // there are no nodes
+    if (!root)
+    {
+        return 0;
+    }
 
+    return 1 + treeSize(root->left) + treeSize(root->right);
 }

main.c

@@ -71,7 +71,7 @@ int main(int argc, char *argv[])
         userInput = inputNumber("Welche Zahl kommt doppelt vor: ");
         measuredSeconds = stopTimer();
 
-        duplicate = getDuplicate(numbers, numberOfElements+1);
+        duplicate = getDuplicate(numbers, numberOfElements);
 
         // check result and update highscores
         if(userInput == duplicate)

numbers.c

@@ -5,67 +5,101 @@
 #include "numbers.h"
 #include "bintree.h"
 
-//Speicher für Array erstellen, zufällige Zahlen von 1-2xlen erzeugen, mittels Binärbaum checken, ob Zahlen einzigartig sind
-//Eine Zahl duplizieren, an zufälliger Stelle einfügen und die Zahl an der Stelle ans Ende schieben
-const int compare (const void *a, const void *b);
+static int compareInt(const void *ptr1, const void *ptr2);
 
+// TODO: getDuplicate und createNumbers implementieren
+/*  *   * Erzeugen eines Arrays mit der vom Nutzer eingegebenen Anzahl an Zufallszahlen.
+ * Sicherstellen, dass beim Befüllen keine Duplikate entstehen.
+ * Duplizieren eines zufälligen Eintrags im Array.
+ * in `getDuplicate()`: Sortieren des Arrays und Erkennen der doppelten Zahl durch Vergleich benachbarter Elemente. */
+
+// 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.
+
+/*
+the implemented tree can't efficiently check if it contains a specific number, but we don't actually need that anyways
+create numbers just counts and checks if the just inserted number sets the isDuplicate pointer
+*/
+// srand should have been called before this function
 unsigned int *createNumbers(unsigned int len)
 {
-  unsigned int *numbers = malloc (sizeof(unsigned int) * len);
-  unsigned int upperLimit = len * 2;
-  int isDuplicate = 0;
-  TreeNode *binTree = NULL;
+  unsigned int *randomNumbers = malloc(len * sizeof(int));
 
-  for (unsigned int i = 0; i < len; i++) {
-    do
+  if (!randomNumbers)
   {
+    return NULL;
+  }
+
+  // including upper limit
+  int upperLimit = len * 2;
+
+  int numberCnt = 0;
+
+  int isDuplicate = 0;
+  TreeNode *root = NULL;
+  // we only need len-1 numbers because 1 will be duplicated
+  while (numberCnt < len - 1)
+  {
+    // numbers up to and including upperLimit without 0
+    int randNum = rand() % upperLimit + 1;
+    // reset isDuplicate
     isDuplicate = 0;
-      numbers[i] = rand () % upperLimit + 1;
-      binTree = addToTree(binTree, &numbers[i], sizeof(unsigned int), compare, &isDuplicate);
-    } while (isDuplicate);
+    // don't forget to set the root here
+    root = addToTree(root, &randNum, sizeof(randNum), (CompareFctType)compareInt, &isDuplicate);
+    if (isDuplicate)
+    {
+      // number already exists
+      continue;
+    }
+    randomNumbers[numberCnt++] = randNum;
   }
 
-  unsigned int duplicate = numbers[rand () % len];
-  int indexDuplicate;
+  // select which number to duplicate
+  int dupNum = randomNumbers[rand() % numberCnt];
+  // ...and where to insert
+  int dupNumIdx = rand() % len;
 
-  do {
-    indexDuplicate = rand() % len;
-  } while (numbers[indexDuplicate] == duplicate);
+  // move the number currently at the dupNumIdx to the end
+  // and insert the dupNum at the index
+  // this also works if the last idx was selected for dupNum
+  randomNumbers[len - 1] = randomNumbers[dupNumIdx];
+  randomNumbers[dupNumIdx] = dupNum;
 
-  numbers[len-1] = numbers[indexDuplicate];
-  numbers[indexDuplicate] = duplicate;
-  
-  return numbers;
+  // clean up memory
+  clearTree(root);
+  return randomNumbers;
 }
 
-//Vergleichsfunktion von qsort
-const int compare (const void *a, const void *b) {
-  const unsigned int *x = a;
-  const unsigned int *y = b;
-  if (*x < *y) {
-    return -1;
-  }
-  else if (*x > *y) {
-    return 1;
-  }
-  else {
-    return 0;
-  }
-}
-
-//Sortiert Zahlen mit qsort, vergleicht dann benachbarte Elemente und gibt bei Erfolg die doppelte Zahl zurück
+// 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 < 2) {
+  unsigned int *numbersCpy = malloc(sizeof(unsigned int) * len);
+  if (!numbersCpy)
+  {
     return 0;
   }
+  memcpy(numbersCpy, numbers, len * sizeof(unsigned int));
+  numbersCpy = numbersCpy; // shadow the numbers array with copy
 
-qsort((void*)numbers, len, sizeof(unsigned int), compare);
+  qsort((void *)numbersCpy, len, sizeof(int), compareInt); // sort the array
 
-for (int i = 0; i < len-1; i++) {
-  if (numbers[i] == numbers [i+1]) {
-    return numbers[i];
+  unsigned int duplicateFound = 0; // zero on errors
+  for (int i = 0; i < len - 1; i++)
+  {
+    if (numbersCpy[i] == numbersCpy[i + 1])
+    {
+      duplicateFound = numbersCpy[i];
+      break;
     }
+  }
+  free(numbersCpy);
+  return duplicateFound;
 }
-  return 0;
+
+static int compareInt(const void *ptr1, const void *ptr2)
+{
+  int num1 = *(int *)ptr1;
+  int num2 = *(int *)ptr2;
+  return num1 - num2;
 }