pvjc24/a3/binary_search_tree.c

#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include "binary_search_tree.h"

void free_tree(node_t *tree) {
    if (tree == NULL) {
        return;
    }

    free_tree(tree->left);
    free_tree(tree->right);

    free(tree);
}
int *sorted_data(node_t *tree) {
    if (tree == NULL) {
        return NULL;
    }

    size_t num_nodes = 0;
    node_t *current = tree;
    while (current != NULL) {
        num_nodes++;
        current = current->right;
    }

    int *sorted_array = (int *)malloc(num_nodes * sizeof(int));
    if (sorted_array == NULL) {
        return NULL;
    }


    size_t index = 0;

    node_t *current_node = tree;
    while (current_node != NULL) {
        if (current_node->left == NULL) {
            sorted_array[index++] = current_node->data;
            current_node = current_node->right;
        } else {
            node_t *predecessor = current_node->left;
            while (predecessor->right != NULL && predecessor->right != current_node) {
                predecessor = predecessor->right;
            }

            if (predecessor->right == NULL) {
                predecessor->right = current_node;
                current_node = current_node->left;
            } else {
                predecessor->right = NULL;
                sorted_array[index++] = current_node->data;
                current_node = current_node->right;
            }
        }
    }

    return sorted_array;
}

node_t *build_tree(int *tree_data, size_t tree_data_len) {
    if (tree_data == NULL || tree_data_len == 0) {
        return NULL;
    }

    node_t *koren = (node_t *)malloc(sizeof(node_t));
    if (koren == NULL) {
        return NULL;
    }

    koren->data = tree_data[0];
    koren->left = NULL;
    koren->right = NULL;

    if (tree_data_len > 1) {
        koren->left = build_tree(tree_data + 1, tree_data_len - 1);
    }

    return koren;
}