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