Level Order Traversal of Binary Tree

string levelOrderTraversal(BinaryTreeNode* root) {
  string result = "";
  //TODO: Write - Your - Code
  
  return result;
}

#include <iostream>
#include <deque>
#include <vector>
#include <string>
#include <sstream>
std::string levelOrderTraversal(BinaryTreeNode* root) {
    if (root == nullptr) {
        return "None";
    }
    std::vector<std::string> result;
    std::deque<BinaryTreeNode*> queue;
    queue.push_back(root);
    while (!queue.empty()) {
        int levelSize = queue.size();
        std::vector<std::string> levelNodes;
        for (int i = 0; i < levelSize; ++i) {
            BinaryTreeNode* temp = queue.front();
            queue.pop_front();
            levelNodes.push_back(std::to_string(temp->data));
            if (temp->left != nullptr) {
                queue.push_back(temp->left);
            }
            if (temp->right != nullptr) {
                queue.push_back(temp->right);
            }
        }
        std::ostringstream oss;
        for (size_t i = 0; i < levelNodes.size(); ++i) {
            if (i != 0) oss << ", ";
            oss << levelNodes[i];
        }
        result.push_back(oss.str());
    }
    std::ostringstream oss;
    for (size_t i = 0; i < result.size(); ++i) {
        if (i != 0) oss << "; ";
        oss << result[i];
    }
    return oss.str();
}
int main(int argc, char* argv[]) {
  BinaryTreeNode* root = create_random_BST(15);
  cout << endl;
  cout << "Inorder = ";
  display_inorder(root);
  cout << "\nLevel order = ";
  cout<< levelOrderTraversal(root);
  
}