Question

Possible Duplicate:
Implement Stack using Two Queues

I want the most efficient way in terms of time complexity to implement stack using two queues

Answer 1

I don’t get why you’d ever need two queues. I’ve seen the answers here and in the dupe thread, and you can do it with just one queue.

From the dupe thread, this has two versions, one that optimizes push, and one that optimizes pop.

Push optimized:

push:  
    enqueue in queue  
pop:  
    n = queue size.
    dequeue an object, and enqueue it immediately after. Do this n - 1 times.
    dequeue object, and return this.

Pop optimized:

push:
    enqueue in queue
    n = queue size.
    dequeue an object, and enqueue it immediately after. Do this n - 1 times.
pop:
    dequeue from queue and return.

Then again, I don’t get why you’d ever want to do this ever. Lambast your professor for making you waste your time with pointless programming questions.