Help with clarification

https://hack.codingblocks.com/app/contests/2022/455/problem

what is the meaning of dequeue efficient

Hello @raghav007 deque is the advance version of queue in which you can perform insertion and deletion at both the ends so you have to form that version of queue using 2 stacks.

I hope I’ve cleared your doubt. I ask you to please rate your experience here
Your feedback is very important. It helps us improve our platform and hence provide you
the learning experience you deserve.

On the off chance, you still have some questions or not find the answers satisfactory, you may reopen
the doubt.