二叉搜索树（C）

二叉搜索树(BinarySearchTree): 用于实现快速的查找, 同时支持快速插入和删除。
BST要求: 在树种的任意一个节点, 其左子树的每个节点的值都要小于该节点的值, 其右子树的每个节点的值都要大于该节点的值。

#include <stdio.h>
#include <stdlib.h>

typedef struct tree_node {
    int value;
    struct tree_node *left;
    struct tree_node *right;
} tree_node_t;

tree_node_t *create_tree_node(int value)
{
    tree_node_t *new_node = (tree_node_t *)malloc(sizeof(tree_node_t));
    if (new_node == NULL) {
        printf("malloc for new tree node failed.\n");
        return NULL;
    }

    new_node->value = value;
    new_node->left = NULL;
    new_node->right = NULL;
    return new_node;
}

void binary_search_tree_insert(tree_node_t **node, int value)
{
    if (*node == NULL) {
        *node = create_tree_node(value);
    } else if (value < (*node)->value) {
        return binary_search_tree_insert(&(*node)->left, value);
    } else if (value > (*node)->value) {
        return binary_search_tree_insert(&(*node)->right, value);
    } else {
        printf("value: %d is alread exist in bst.\n", value);
    }
}

void inorder_traversal(tree_node_t *root)
{
    if (root == NULL) {
        return;
    }

    inorder_traversal(root->left);
    printf("%d ", root->value);
    inorder_traversal(root->right);
}

int main()
{
    tree_node_t *root = NULL;
    int numbers[] = {50, 30, 70, 10, 40, 60, 90, 20, 80, 100, 0};
    int size = sizeof(numbers) / sizeof(numbers[0]);

    for (int i = 0; i < size; i++) {
        binary_search_tree_insert(&root, numbers[i]);
    }

    printf("inorder traversal of binary search tree: \n");
    inorder_traversal(root);

    return 0;
}