Question

I want to maintain two queues, Queue A is for pop , Queue B is for backup, so if i pop all objects out from A, how do I restore Queue A from B?

while (still has input)
     A.push(input)
     B.push(input)

while A is not empty
      A.pop()

Then how do I restore A from B??? In the meantime, I still want to keep B as my backup.

I know some very stupid way to do it , like assign one more queue C and then pop all Bout. And then restore B from queue C

Answer 1

One way is to use the copy module.

import copy

while (still has input)
    A.push(input)
    B.push(input)

while A is not empty
    A.pop()

A = copy.deepcopy(B)