Binary Search Tree in C

BinarySearchTree.c

/*
 * Tree.c
 *
 *  Created on: 5 Nov 2015
 *      Author: Alex
 */

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

struct node {
	int val;
	struct node* left;
	struct node* right;
};

struct node* newNode(int val){
	struct node* tmp = malloc(sizeof(struct node));
	tmp->left = NULL;
	tmp->right = NULL;
	tmp->val = val;
	return tmp;
}


struct node* insert(struct node* node, int val){

	if(node == NULL){
		return newNode(val);
	}else{
		if(val <= node->val){
			node->left = insert(node->left, val);
		}else{
			node->right = insert(node->right, val);
		}
		return node;
	}

}

int lookup(struct node* node, int val){

	if(node == NULL){
		return 0;
	}else{
		if(node->val == val){
			return 1;
		}

		if(val < node->val){
			return lookup(node->left, val);
		}else{
			return lookup(node->right, val);
		}

	}
}

int main(){

	struct node* root = NULL;

	root = insert(root, 5);
	root = insert(root, 10);
	root = insert(root, 7);
	root = insert(root, 2);
	root = insert(root, 1);

	if(lookup(root, 7)){
		printf("exists");
	}else{
		printf("does not exist");
	}

}