Left View of a binary tree

// C++ program to print left 
// view of Binary Tree 
#include <bits/stdc++.h> 
using namespace std; 

class node { 
public: 
	int data; 
	node *left, *right; 
}; 

// A utility function to create a new Binary Tree node 
node* newNode(int item) 
{ 
	node* temp = new node(); 
	temp->data = item; 
	temp->left = temp->right = NULL; 
	return temp; 
} 

// Recursive function to print left view of a binary tree. 
void leftViewUtil(node* root, int level, int* max_level) 
{ 
	// Base Case 
	if (root == NULL) 
		return; 

	// If this is the first node of its level 
	if (*max_level < level) { 
		cout << root->data << "\t"; 
		*max_level = level; 
	} 

	// Recur for left and right subtrees 
	leftViewUtil(root->left, level + 1, max_level); 
	leftViewUtil(root->right, level + 1, max_level); 
} 

// A wrapper over leftViewUtil() 
void leftView(node* root) 
{ 
	int max_level = 0; 
	leftViewUtil(root, 1, &max_level); 
} 

// Driver code 
int main() 
{ 
	node* root = newNode(12); 
	root->left = newNode(10); 
	root->right = newNode(30); 
	root->right->left = newNode(25); 
	root->right->right = newNode(40); 

	leftView(root); 

	return 0; 
}