this.levelOrder = function(root) {
    if (!root) {
        return;
    }

    const queue = [];
    queue.push(root);

    while (queue.length > 0) {
        const node = queue.shift();
        process.stdout.write(node.data + " ");

        if (node.left) {
            queue.push(node.left);
        }
        if (node.right) {
            queue.push(node.right);
        }
    }
};

// Start of function levelOrder
    this.levelOrder = function(root) {
    if (!root) return;

        const queue = [];
        queue.push(root);

        while (queue.length > 0) { 
            const levelSize = queue.length; 

        for (let i = 0; i < levelSize; i++) { 
        const node = queue.shift(); 
        process.stdout.write(node.data + ' '); 

        if (node.left) queue.push(node.left); 
        if (node.right) queue.push(node.right);  
        }
        }  
    }; // End of function levelOrder

 def levelOrder(self,root):
    queue = [root]
    for item in queue:
        if item.left:
            queue.append(item.left)
        if item.right:
            queue.append(item.right)
    print(" ".join([str(i.data) for i in queue]))

void levelOrder(Node * root){
 vector<Node*> oQ;
 
 if (nullptr != root) {
  oQ.push_back(root);

  for(int i=0; i<oQ.size(); i++) {
   cout<<oQ[i]->data<<" ";

   if (nullptr != oQ[i]->left)
    oQ.push_back(oQ[i]->left);

   if (nullptr != oQ[i]->right)
    oQ.push_back(oQ[i]->right);
  }
 }
}