spiral

void printSpiral(Node *root)
{
   if(root == NULL)return;
   deque<Node*>q;
   q.push_front(root);
   int LtoR = 0;
   while(!q.empty()){
      int sz = q.size();
      while(sz--){
          Node*temp;
          if(LtoR){
              temp = q.front();
              cout<<temp->data<<" ";
              q.pop_front();
              if(temp->left)q.push_back(temp->left);
              if(temp->right)q.push_back(temp->right);
          }
          else{
              temp = q.back();
              cout<<temp->data<<" ";
              q.pop_back();

              if(temp->right)q.push_front(temp->right);
              if(temp->left)q.push_front(temp->left);
          }
      }
      LtoR = 1 - LtoR;
   }
}