Doblespiel/bintree.c

#include <string.h>
#include "stack.h"
#include "bintree.h"

//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),
    * `nextTreeData`: Traversierung mit Hilfe des zuvor implementierten Stacks. */

#include <string.h>
#include "stack.h"
#include "bintree.h"

// 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).
TreeNode *addToTree(TreeNode *root, const void *data, size_t dataSize, CompareFctType compareFct, int *isDuplicate)
{
    if (data == NULL || dataSize == 0 || compareFct == NULL)
        return root;

    // Basisfall: leerer Baum -> neuen Knoten anlegen
    if (root == NULL)
    {
        TreeNode *node = (TreeNode *)malloc(sizeof(TreeNode));
        if (node == NULL)
            return root;

        node->data = malloc(dataSize);
        if (node->data == NULL)
        {
            free(node);
            return root;
        }

        memcpy(node->data, data, dataSize);
        node->left = NULL;
        node->right = NULL;

        if (isDuplicate != NULL)
            *isDuplicate = 0;

        return node;
    }

    int cmp = compareFct(data, root->data);

    if (cmp < 0)
    {
        root->left = addToTree(root->left, data, dataSize, compareFct, isDuplicate);
    }
    else if (cmp > 0)
    {
        root->right = addToTree(root->right, data, dataSize, compareFct, isDuplicate);
    }
    else // cmp == 0 -> Duplikat
    {
        if (isDuplicate != NULL)
        {
            *isDuplicate = 1;
            // Duplikat NICHT einfügen
        }
        else
        {
            // Duplikate zulassen -> konsistent z.B. rechts einfügen
            root->right = addToTree(root->right, data, dataSize, compareFct, NULL);
        }
    }

    return root;
}

// 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)
{
    // Zustandsbehafteter Iterator wie strtok()
    static StackNode *stack = NULL;

    // Neuer Baum -> alten Stack leeren, Traversierung neu starten
    if (root != NULL)
    {
        clearStack(stack);
        stack = NULL;

        TreeNode *current = root;
        while (current != NULL)
        {
            stack = push(stack, current);
            current = current->left;
        }
    }

    // Kein aktueller Baum / Traversierung zu Ende
    if (stack == NULL)
        return NULL;

    // Nächsten Knoten holen
    TreeNode *node = (TreeNode *)top(stack);
    stack = pop(stack);

    // Rechtses Kind und alle seine linken Kinder auf den Stack
    TreeNode *current = node->right;
    while (current != NULL)
    {
        stack = push(stack, current);
        current = current->left;
    }

    return node->data;
}

// Releases all memory resources (including data copies).
void clearTree(TreeNode *root)
{
    if (root == NULL)
        return;

    clearTree(root->left);
    clearTree(root->right);

    free(root->data);
    free(root);
}

// Returns the number of entries in the tree given by root.
unsigned int treeSize(const TreeNode *root)
{
    if (root == NULL)
        return 0;

    return 1u + treeSize(root->left) + treeSize(root->right);
}