levelwise cpp

// program to traverse and print nodes of binary tree using level wise traversal
#include <iostream>
#include <queue>
#include <map>

using namespace std;

// node class
class node{
public:
    int data;
    int hd;
    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;
}

// BFS traversal iterative using queue
void level_wise_traversal(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;

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

            // 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);
            }
        }
        cout<<endl;
    }

}

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);
    head->hd = 0;

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

}



/*

Level wise traversal of the above binary tree is :
NODES at level 0 are : 1
NODES at level 1 are : 2 3
NODES at level 2 are : 4 5 6
NODES at level 3 are : 7 8
NODES at level 4 are : 9 11
NODES at level 5 are : 10
Process finished with exit code 0

*/