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Opower interview question

Implement a queue using only stacks.

Interview Answers

Anonymous

28 May 2011

actually this is doable with 2 stacks nvm: use 2 Stacks, stackA and stackB. when you enqueue, push the item onto stackA. When you dequeue, if stackB is empty pop everything from stackA and push onto stack B. Pop from stackB

3

Anonymous

28 May 2011

use 2 Stacks, stackA and stackB. when you enqueue, push the item onto stackA. When you dequeue, pop everything from stackA and push onto stack B. Pop from stackB.

1

Anonymous

13 Jun 2018

#3 corrected use 2 stacks. it depedents server IP address availabe.

Anonymous

28 May 2011

the above answer is incorrect. I can't figure out how to edit, so here is the corrected version: use 3 Stacks, stackA, stackB, stackC. when you enqueue, push the item onto stackA. When you dequeue, pop everything from stackB and push onto stackC, pop everything from stackA and push onto stack B, pop everything from stackC and push onto stackB. Pop from stackB.