left view iter cpp

// http://code2begin.blogspot.com
// program to print left view binary tree iteratively

/**
 * Created by MOHIT on 25-05-2018.
 */
#include <iostream>
#include <queue>
#include <map>
#include <list>

using namespace std;

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

// function that returns a pointer to new node
node* createNode(int element){
    node* temp = (node*) malloc(sizeof(node));
    temp->data = element;
    temp->left = NULL;
    temp->right = NULL;
    return temp;
}

// BFS iretative using queue
void left_view_iter(node* root){
    if(root == NULL){
        return;
    }

    // creating a Queue for storing node for level wise traversal
    queue<node *> Q;
    Q.push(root);
    int level = 0, max_level = 0;

    while(!Q.empty()){
        // store the current size of the Q
        int count = Q.size();
        level += 1;
        while(count--) {
            // pop the first node from the queue
            node *NODE = Q.front();
            Q.pop();
            if (max_level < level) {
                cout << NODE->data << " ";
                max_level = level;
            }

            // push the left child on queue
            if (NODE->left != NULL) {
                Q.push(NODE->left);
            }

            // push the right child on queue
            if (NODE->right != NULL) {
                Q.push(NODE->right);
            }
        }
    }

}


int main() {
    node* head = createNode(1);
    head->left = createNode(2);
    head->right = createNode(3);
    head->left->left = createNode(4);
    head->left->right = createNode(5);
    head->right->right = createNode(6);
    head->left->left->right = createNode(7);
    head->right->right->left = createNode(8);
    head->left->left->right->left = createNode(9);
    head->left->left->right->left->left = createNode(10);
    head->right->right->left->right = createNode(11);

    cout<<"Left view of the binary tree is : "<<endl;
    left_view_iter(head);
    return 0;
}


/*

Left view of the binary tree is :
1 2 4 7 9 10
Process finished with exit code 0

*/