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

typedef struct _BSTNode { // canonical name "struct _BSTNode:
    int value;
    struct _BSTNode* left; // size of address is the same
                           // no matter the type
    struct _BSTNode* right;
} BSTNode; // shortcut name "BSTNode"

void insert(int value, BSTNode** a_root) {
    if (*a_root == NULL) {
        BSTNode* new_node = malloc(sizeof(*new_node));
        *new_node = (BSTNode) {
            .value = value, .left = NULL, .right = NULL
        };
        *a_root = new_node;
    }
    // value is smaller, put on left
    else if (value < (*a_root)->value) {
        insert(value, &((*a_root)->left));  
    }
    // value is larger, put on right
    // value is equal also ends up on right
    else {
        insert(value, &((*a_root)->right)); 
    }
}

void _plain_print_tree(const BSTNode* root) {
    // TODO: explain this example more in depth
    if (root != NULL) {
        _plain_print_tree(root->left);
        printf("[%d] ", root->value);
        _plain_print_tree(root->right);
    }
}

void print_tree(BSTNode const* root, char* prefix) {
    printf("%s", prefix);
    _plain_print_tree(root);
    printf("\n");
}

int main(int argc, char* argv[]) {
    // tree of size 0
    BSTNode* root = NULL;
    assert(root == NULL);
    print_tree(root, "Empty Tree: ");

    // tree of size 1
    insert(6, &root);
    assert(root != NULL);
    assert(root->left == NULL);
    assert(root->right == NULL);
    assert(root->value == 6);
    print_tree(root, "Tree Size 1: ");

    // tree of size 2
    insert(5, &root);
    assert(root->left != NULL);
    assert(root->left->left == NULL);
    assert(root->left->right == NULL);
    assert(root->left->value == 5);
    print_tree(root, "Tree Size 2: ");

    // tree of size 3
    insert(8, &root);
    assert(root->right != NULL);
    assert(root->right->left == NULL);
    assert(root->right->right == NULL);
    assert(root->right->value == 8);
    
    
    // tree of size 4
    insert(2, &root);
    assert(root->left->left != NULL);
    assert(root->left->left->left == NULL);
    assert(root->left->left->right == NULL);
    assert(root->left->left->value == 2);
    print_tree(root, "Tree Size 4: ");

    // TODO: free the tree

    return EXIT_SUCCESS;
}
/* vim: set tabstop=4 shiftwidth=4 fileencoding=utf-8 noexpandtab: */

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