WAP To Find the Smallest and Largest Elements in the Binary Search Tree

This C Program Finds the Smallest and Largest Elements in the Binary Search Tree.
Here is source code of the C Program to Find the Smallest and Largest Elements in the Binary Search Tree. The C program is successfully compiled and run on a Linux system. The program output is also shown below.

Program

/*
 * C Program To Find the Smallest and Largest Elements 
 * in the Binary Search Tree
 *                    40
 *                   /  \
 *                  20   60
 *                 /  \   \
 *                10  30   80
 *                         \
 *                         90    
 *            (Given Binary Search Tree)    
 *
 */
#include <stdio.h>
#include <stdlib.h>
struct btnode {
	int value;
	struct btnode *l;
	struct btnode *r;
}
*root  =  NULL;
typedef struct btnode N;
N* new(int);
void create();
void preorder(N *t);
void min_max(N *t);
void main() {
	int choice;
	create();
	while (1) {
		printf("Enter the choice\n");
		printf("1-Display : 2-Min & Max element : 3-Exit\n");
		scanf("%d", &choice);
		switch (choice) {
			case 1:
			            printf("preorder preorder of tree elements\n");
			preorder(root);
			printf("\n");
			break;
			case 2:
			            min_max(root);
			break;
			case 3:
			            exit(0);
			default:
			            printf("Enter the right choice\n");
		}
	}
}
/* creating temporary node */
N* new(int data) {
	N* temp = (N*)malloc(sizeof(N));
	temp->value = data;
	temp->l = NULL;
	temp->r = NULL;
	return(temp);
}
/* Creating the binary search tree */
void create() {
	root = new(40);
	root->l = new(20);
	root->r = new(60);
	root->l->l = new(10);
	root->l->r = new(30);
	root->r->r = new(80);
	root->r->r->r = new(90);
}
/* To display preorder traversal of the tree */
void preorder(N *temp) {
	printf("%d->", temp->value);
	if (temp->l != NULL)
	        preorder(temp->l);
	if (temp->r != NULL)
	        preorder(temp->r);
}
/* TO find the minimum and maximum values in the given tree */
void min_max(N *temp) {
	while (temp->l != NULL)
	        temp = temp->l;
	printf("Minimum value  = %d\n", temp->value);
	temp = root;
	while (temp->r != NULL)
	        temp = temp->r;
	printf("Maximum value  = %d\n", temp->value);
}

Output

Enter the choice
1-Display : 2-Min & Max element : 3-Exit
1
preorder preorder of tree elements
40->20->10->30->60->80->90
Enter the choice
1-Display : 2-Min & Max element : 3-Exit
2
Minimum value  = 10
Maximum value  = 90
Enter the choice
1-Display : 2-Min & Max element : 3-Exit
3