Q3(a) Suppose a stack implementation supports an instruction REVERSE, which reverses the order of elements on the stack, in addition to the PUSH and POP instructions. Implement queue function using these three functions and only one stack.
Question
Q3(a) Suppose a stack implementation supports an instruction REVERSE, which reverses the order of elements on the stack, in addition to the PUSH and POP instructions. Implement queue function using these three functions and only one stack.
Solution
Sure, here is a simple implementation of a queue using a stack with PUSH, POP, and REVERSE operations:
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Initialize an empty stack.
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To implement the enqueue operation (inserting an element in the queue), we simply use the PUSH operation on the stack.
def enqueue(element):
stack.push(element)
- To implement the dequeue operation (removing an element from the queue), we first check if the stack is empty. If it is, we return an error message or throw an exception. If it's not, we use the REVERSE operation to reverse the order of the elements in the stack, then use the POP operation to remove the top element, and finally use the REVERSE operation again to restore the order of the remaining elements.
def dequeue():
if stack.isEmpty():
return "Queue is empty"
else:
stack.reverse()
element = stack.pop()
stack.reverse()
return element
This way, the first element inserted in the queue (which is at the bottom of the stack) will be the first one to be removed (since it becomes the top element of the stack after the first REVERSE operation), following the First-In-First-Out (FIFO) behavior of queues.
Similar Questions
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