How many stacks are needed to implement a queue? Consider the situation where no other data structure like arrays, linked list is available to you.ans.

To implement a queue using stacks, you would need two stacks. Here's a step-by-step guide on how to do it:

1. Create two stacks, let's call them stack1 and stack2.
2. When enqueuing an element, push it into stack1.
3. When dequeuing an element, if stack2 is empty, pop all elements from stack1 and push them into stack2. Then, pop the top element from stack2.
4. If stack2 is not empty when dequeuing, simply pop the top element from stack2.

This way, the order of elements is preserved as in a queue, with the first element enqueued being the first one dequeued (FIFO: First In First Out). The first stack is used for enqueuing and the second stack is used for dequeuing.