Diagonal of a Binary Tree

/* A binary tree node
struct Node
{
    int data;
    Node* left, * right;
}; */


vector<int> diagonal(Node *root)
{
   
   vector<int> ans;
   if(root == NULL){
       return ans;
   }
   queue<Node*> q;
   q.push(root);
   while(!q.empty()){
       Node* temp = q.front();
       q.pop();
       while(temp){
           if(temp->left){
               q.push(temp->left);
           }
           ans.push_back(temp->data);
           temp = temp->right;
       }
   }
   return ans;
   
}