BST.c

#include <stdio.h>
#include <stdlib.h>
int flag=0;

typedef struct BST
{
	int data;
	struct BST *lchild, *rchild;
} node;

void insert(node *,node *);
void inorder(node *);
void preorder(node *);
void postorder(node *);
node *search(node *, int, node **);

node *get_node()
{
node *temp;
temp = (node *) malloc(sizeof(node));
temp->lchild = NULL;
temp->rchild = NULL;
return temp;
}

void insert (node *root, node *new_node)
{
	if (new_node->data<root->data)
	{
		if (root->lchild == NULL)
			root->lchild = new_node;
		else
			insert(root->lchild, new_node);
	}
	if (new_node->data > root->data)
	{
		if (root->rchild == NULL)
			root->rchild = new_node;
		else
			insert(root->rchild, new_node);
	}
}

node *search(node *root, int key, node **parent)
{
node *temp;
temp=root;
while(temp != NULL)
{
	if (temp->data==key)
	{
		printf("\nThe %d Element is Present", temp->data) ;
		flag=1;
		return temp;
	}
	*parent=temp;
	if (temp->data>key)
		temp=temp->lchild;
	else
		temp=temp->rchild;
}return NULL;
}

void inorder(node *temp)
{
	if(temp != NULL)
	{
    inorder (temp -> lchild) ;
    printf ("\t%d\t", temp->data) ;
    inorder (temp->rchild) ;
	}
}

void preorder(node *temp)
{
	if (temp != NULL)
	{
	printf ("\t%d\t", temp->data) ;
	preorder (temp->lchild) ;
	preorder (temp->rchild) ;
	}
}

void postorder(node *temp)
{
	if (temp != NULL)
	{
	postorder (temp->lchild) ;
	postorder (temp->rchild) ;
	printf ("\t%d\t", temp->data) ;
	}
}

void main()
{
int choice;
int ans = 1;
int key;
node *new_node, *root, *tmp, *parent;
node *get_node();
root = NULL;
printf("\nProgram For Binary Search Tree ");
do
{
printf ("\nl.Create");
printf ("\n2.Search");
printf ("\n3.Recursive Traversals") ;
printf ("\n4.Exit") ;
printf("\nEnter your choice :");
scanf("%d", &choice) ;
switch (choice)
{
case 1:
	do
	{
	new_node = get_node();
	printf("\nEnter The Element ");
	scanf("%d", &new_node->data) ;
	if (root == NULL)
		root = new_node;
	else
		insert (root, new_node);
	printf("\nWant To enter More Elements? (1/0)");
	scanf("%d",&ans);
	}while(ans);
	break;

case 2:
 	printf("\nEnter Element to be searched :");
	scanf("%d", &key);
	tmp = search(root, key, &parent);
	if (flag==1)
		printf("\nParent of node %d is %d", tmp->data, parent->data);
	else
		printf("\n The %d Element is not Present", key) ;
	flag=0;
	break;

case 3:
	if (root == NULL)
		printf("Tree Is Not Created");
	else
	{
		printf("\nThe Inorder display : ");
		inorder (root) ;
		printf("\nThe Preorder display : ");
		preorder (root) ;
		printf("\nThe Postorder display : ");
		postorder (root) ;
	}
	break;
}
} while (choice != 4);
}