How do you implement stack using queues?

A stack can be implemented using two queues. We know that a queue supports enqueue and dequeue operations. Using these operations, we need to develop push, pop operations.
Let stack be ‘s’ and queues used to implement be ‘q1’ and ‘q2’. Then, stack ‘s’ can be implemented in two ways:
1. By making push operation costly:

This method ensures that the newly entered element is always at the front of ‘q1’ so that pop operation just dequeues from ‘q1’.
‘q2’ is used as auxillary queue to put every new element in front of ‘q1’ while ensuring pop happens in O(1) complexity.
Pseudocode:
Push element to stack s: Here push takes O(n) time complexity.
push(s, data):
Enqueue data to q2
Dequeue elements one by one from q1 and enqueue to q2.
Swap the names of q1 and q2
Pop element from stack s: Takes O(1) time complexity.
pop(s):
dequeue from q1 and return it.
2. By making pop operation costly:

In push operation, the element is enqueued to q1.
In pop operation, all the elements from q1 except the last remaining element, are pushed to q2 if it is empty. That last element remaining of q1 is dequeued and returned.
Pseudocode:
Push element to stack s: Here push takes O(1) time complexity.
push(s,data):
Enqueue data to q1
Pop element from stack s: Takes O(n) time complexity.
pop(s):
Step1: Dequeue every elements except the last element from q1 and enqueue to q2.
Step2: Dequeue the last item of q1, the dequeued item is stored in result variable.
Step3: Swap the names of q1 and q2 (for getting updated data after dequeue)
Step4: Return the result