spiral BT cpp

// http://code2begin.blogspot.com
// Program to print the given binary tree in a spiral order level wise traversal
#include <iostream>
#include <stack>

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->hd = -1;
    temp->left = NULL;
    temp->right = NULL;
    return temp;
}

// function to print the tree using spiral level wise traversal
void spiral_traversal(node* root){
    if (root == NULL){
        return;
    }
    stack<node *> STACK1, STACK2;
    int level = 1;
    STACK1.push(root);
    while(!STACK1.empty() || !STACK2.empty()){
        cout<<"\nNodes at level "<<level<<" are : ";
        level += 1;
        while (!STACK1.empty()){
            // pop the first node from the queue
            node *NODE = STACK1.top();
            STACK1.pop();
            cout<<NODE->data<<" ";

            // push the left child on queue
            if (NODE->right != NULL) {
                STACK2.push(NODE->right);
            }

            // push the right child on queue
            if (NODE->left != NULL) {
                STACK2.push(NODE->left);
            }
        }

        cout<<"\nNodes at level "<<level<<" are : ";
        level += 1;
        while (!STACK2.empty()){
            // pop the first node from the queue
            node *NODE = STACK2.top();
            STACK2.pop();
            cout<<NODE->data<<" ";

            // push the left child on queue
            if (NODE->right != NULL) {
                STACK1.push(NODE->right);
            }

            // push the right child on queue
            if (NODE->left != NULL) {
                STACK1.push(NODE->left);
            }
        }
    }
}


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<<"SPIRAL Level wise traversal of the above binary tree is : "<<endl;
    spiral_traversal(head);

}