Minimum number of queues to implement stack is ___________

The minimum number of queues needed to implement a stack is two.

Here is the step by step process:

1. Push operation:

   • Enqueue in the first queue.

2. Pop operation:

   • While the size of the first queue is more than 1, pipe dequeued items from the first queue into the second queue.
   • Dequeue the last item of the first queue, this is the popped element.
   • Swap the names of the first queue and the second queue.

In this way, by using two queues, we can implement a stack.