Different Ways to implement Stack and Queue together

There are several ways to implement a data structure that combines both a stack and a queue:

• Using two stacks: We can simulate a queue using two stacks. We call these stacks input and output. We add elements to the input stack, and when we want to remove an element, we move all the elements from the input stack to the output stack. This will reverse the order of the elements, effectively simulating a queue. We can then remove an element from the output stack.
• Using two queues: We can simulate a stack using two queues. We call these queues q1 and q2. When we add an element, we add it to the q1 queue. When we want to remove an element, we move all the elements from q1 to q2, except for the last element. We can then remove the last element from q1 and repeat the process.
• Using a circular buffer: We can use a circular buffer to implement a data structure that combines both a stack and a queue. We can use an array of fixed size, and two pointers front and rear to keep track of the elements. When we add an element, we insert it at the rear of the array. When we remove an element, we remove it from the front of the array. We can use a variable ‘count’ to keep track of the number of elements in the buffer. If ‘count’ reaches the maximum size of the buffer, we can either resize the buffer or discard the oldest element and add the new element.
• Using a deque: A deque (double-ended queue) is a data structure that allows the insertion and removal of elements from both ends. We can use a deque to implement a data structure that combines both a stack and a queue. When we want to add an element, we can insert it at the front of the deque. When we want to remove an element, we can remove it from the back of the deque. This will simulate a stack. We can also add elements to the back of the deque to simulate a queue.