Basic binary search tree routines
#include <stdio.h>
#include <stdlib.h>
struct tnode {
int data;
struct tnode *left;
struct tnode *right;
};
/* insert, swap, search value, search minimum and search maximum values */
struct tnode *tnode_insert(struct tnode *p, int value);
struct tnode *tnode_swap(struct tnode *p);
struct tnode *tnode_search(struct tnode *p, int key);
struct tnode *tnode_searchmin(struct tnode *p);
struct tnode *tnode_searchmax(struct tnode *p);
/* destroy, count tree nodes */
void tnode_destroy(struct tnode *p);
int tnode_count(struct tnode *p);
/* print binary tree inorder, preorder, postorder [recursive] */
void print_inorder(struct tnode *p);
void print_preorder(struct tnode *p);
void print_postorder(struct tnode *p);
int main(void) {
int demo_nr[] = {1, 3, 4, 7, 2, 9, 9, 0, 5, 6, 8, 7, 1, 2, 4};
struct tnode *root = NULL;
struct tnode *searchval = NULL;
int querry = 0;
int i = 0;
/* demo: insert some nr's into the binary tree */
for(i = 0; i < 15; i++)
root = tnode_insert(root, demo_nr[i]);
printf("=-=-=\n");
printf("Total number of tree nodes: %d\n", tnode_count(root));
printf("inorder : ");
print_inorder(root);
printf("\n");
printf("preorder : ");
print_preorder(root);
printf("\n");
printf("postorder: ");
print_postorder(root);
printf("\n");
printf("=-=-=\n");
printf("Enter integer, find: ");
scanf("%d", &querry);
searchval = tnode_search(root, querry);
if(searchval == NULL)
printf(" * %d Not! found in btree\n", querry);
else
printf(" * Found! %d in btree\n", searchval->data);
searchval = NULL;
printf("Searching for Minimum value\n");
searchval = tnode_searchmin(root);
if(searchval == NULL)
printf(" * Minimum Not! found in btree ?\n");
else
printf(" * Found! minimum value %d in btree\n", searchval->data);
searchval = NULL;
printf("Searching for Maximum value\n");
searchval = tnode_searchmax(root);
if(searchval == NULL)
printf(" * Maximum Not! found in btree ?\n");
else
printf(" * Found! Maximum value %d in btree\n", searchval->data);
printf("=-=-=\n");
printf("Exchanging all tree nodes: left <-> right\n");
root = tnode_swap(root);
printf("inorder : ");
print_inorder(root);
printf("\n");
printf("preorder : ");
print_preorder(root);
printf("\n");
printf("postorder: ");
print_postorder(root);
printf("\n");
printf("=-=-=\n");
printf("Destroying btree... bye!\n");
tnode_destroy(root);
return 0;
}
/* insert a tnode into the binary tree */
struct tnode *tnode_insert(struct tnode *p, int value) {
struct tnode *tmp_one = NULL;
struct tnode *tmp_two = NULL;
if(p == NULL) {
/* insert [new] tnode as root node */
p = (struct tnode *)malloc(sizeof(struct tnode));
p->data = value;
p->left = p->right = NULL;
} else {
tmp_one = p;
/* Traverse the tree to get a pointer to the specific tnode */
/* The child of this tnode will be the [new] tnode */
while(tmp_one != NULL) {
tmp_two = tmp_one;
if(tmp_one ->data > value)
tmp_one = tmp_one->left;
else
tmp_one = tmp_one->right;
}
if(tmp_two->data > value) {
/* insert [new] tnode as left child */
tmp_two->left = (struct tnode *)malloc(sizeof(struct tnode));
tmp_two = tmp_two->left;
tmp_two->data = value;
tmp_two->left = tmp_two->right = NULL;
} else {
/* insert [new] tnode as left child */
tmp_two->right = (struct tnode *)malloc(sizeof(struct tnode));
tmp_two = tmp_two->right;
tmp_two->data = value;
tmp_two->left = tmp_two->right = NULL;
}
}
return(p);
}
/* print binary tree inorder */
void print_inorder(struct tnode *p) {
if(p != NULL) {
print_inorder(p->left);
printf("%d ", p->data);
print_inorder(p->right);
}
}
/* print binary tree preorder */
void print_preorder(struct tnode *p) {
if(p != NULL) {
printf("%d ", p->data);
print_preorder(p->left);
print_preorder(p->right);
}
}
/* print binary tree postorder */
void print_postorder(struct tnode *p) {
if(p != NULL) {
print_postorder(p->left);
print_postorder(p->right);
printf("%d ", p->data);
}
}
/* returns the total number of tree nodes */
int tnode_count(struct tnode *p) {
if(p == NULL)
return 0;
else {
if(p->left == NULL && p->right == NULL)
return 1;
else
return(1 + (tnode_count(p->left) + tnode_count(p->right)));
}
}
/* exchange all left and right tnodes */
struct tnode *tnode_swap(struct tnode *p) {
struct tnode *tmp_one = NULL;
struct tnode *tmp_two = NULL;
if(p != NULL) {
tmp_one = tnode_swap(p->left);
tmp_two = tnode_swap(p->right);
p->right = tmp_one;
p->left = tmp_two;
}
return(p);
}
/* locate a value in the btree */
struct tnode *tnode_search(struct tnode *p, int key) {
struct tnode *temp;
temp = p;
while(temp != NULL) {
if(temp->data == key)
return temp;
else if(temp->data > key)
temp = temp->left;
else
temp = temp->right;
}
return NULL;
}
/* locate a minimum value in the btree */
struct tnode *tnode_searchmin(struct tnode *p) {
if(p == NULL)
return NULL;
else
if(p->left == NULL)
return p;
else
return tnode_searchmin(p->left);
}
/* locate a maximum value in the btree */
struct tnode *tnode_searchmax(struct tnode *p) {
if(p != NULL)
while(p->right != NULL)
p = p->right;
return p;
}
/* destroy the binary tree */
void tnode_destroy(struct tnode *p) {
if(p != NULL) {
tnode_destroy(p->left);
tnode_destroy(p->right);
free(p);
}
}
