二叉查找树(简单C实现)

#ifndef _BIN_TREE_H
#define _BIN_TREE_H

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

struct _Tree_node
{
    int data;
    struct _Tree_node *left;
    struct _Tree_node *right;
};

typedef int element_type;
typedef struct _Tree_node *search_tree;
typedef struct _Tree_node *position;

position find(element_type __x, search_tree tree)
{
    if (tree == NULL) {
        printf("No this node!\n");
        return NULL;
    }
    else if (__x < tree->data) {
        return find(__x, tree->left);
    }
    else if (__x > tree->data) {
        return find(__x, tree->right);
    }
    else {
        return tree;
    }
}

position find_min(search_tree tree)
{
    if (tree == NULL) {
        return NULL;
    }
    else if (tree->left == NULL) {
        return tree;
    }
    else {
        return find_min(tree->left);
    }
}

position find_max(search_tree tree)
{
    if (tree == NULL) {
        return NULL;
    }
    else if (tree->right == NULL) {
        return tree;
    }
    else {
        return find_max(tree);
    }
}

void insert(element_type __x, search_tree *tree)
{
    if (*tree == NULL) {
        *tree = (search_tree) malloc((size_t) 1 * sizeof(struct _Tree_node));
        if (*tree == NULL) {
            printf("out of memory.\n");
            exit(1);
        }
        else {
            (*tree)->data = __x;
            (*tree)->left = (*tree)->right = NULL;
        }
    }
    else if (__x < (*tree)->data) {
        insert(__x, &((*tree)->left));
    }
    else if (__x > (*tree)->data) {
        insert(__x, &((*tree)->right));
    }
    else {
        ;
    }
}

void delete(element_type __x, search_tree *tree)
{
    position tmp = NULL;

    if (*tree == NULL) {
        printf("Not found!\n");
    }
    else if (__x < (*tree)->data) {
        delete(__x, &((*tree)->left));
    }
    else if (__x > (*tree)->data) {
        delete(__x, &((*tree)->right));
    }
    else if ((*tree)->left && (*tree)->right) {
        tmp = find_min((*tree)->right);
        (*tree)->data = tmp->data;
        delete((*tree)->data, &((*tree)->right));
    }
    else {
        tmp = *tree;
        if ((*tree)->left == NULL) {
            *tree = (*tree)->right;
        }
        else if ((*tree)->right == NULL) {
            *tree = (*tree)->left;
        }

        free(tmp);
    }
}

void print_by_pre(search_tree tree)
{
    if (tree != NULL) {
        printf("value is %d.\n", tree->data);
        print_by_pre(tree->left);
        print_by_pre(tree->right);
    }
}

void print_by_in(search_tree tree)
{
    if (tree != NULL) {
        print_by_in(tree->left);
        printf("value is %d.\n", tree->data);
        print_by_in(tree->right);
    }
}

void print_by_post(search_tree tree)
{
    if (tree != NULL) {
        print_by_post(tree->left);
        print_by_post(tree->right);
        printf("value is %d.\n", tree->data);
    }
}

#endif