class QueueUsingStack(object):
def __init__(self):
self._stack_one = Stack()
self._stack_two = Stack()
def __str__(self):
return self._stack_one.__str__()
def enqueue(self, element):
'''
:param element: element to be enqueued in the queue
'''
while not self._stack_one.is_empty():
self._stack_two.push(self._stack_one.pop())
self._stack_one.push(element)
while not self._stack_two.is_empty():
self._stack_one.push(self._stack_two.pop())
return
def dequeue(self):
if self._stack_one.is_empty():
raise UnderflowException
return self._stack_one.pop()
class BufferedQueue:
def __init__(self, limit):
self.limit = limit
self.enqueued = Stack()
self.dequeued = Stack()
def __str__(self):
return self.enqueued.__str__() + self.dequeued.__str__(
) + f' buffer limit {self.limit}'
def enqueue(self, item):
if self.size() < self.limit:
self.enqueued.push(item)
return True
else:
return False
def dequeue(self):
if self.dequeued.size() > 0:
return self.dequeued.pop()
while self.enqueued.size() > 1:
self.dequeued.push(self.enqueued.pop())
return self.enqueued.pop()
def next(self):
if self.dequeued.size() > 0:
return self.dequeued.last()
else:
return self.enqueued.first()
def last(self):
if self.enqueued.size() > 0:
return self.enqueued.last()
else:
return self.dequeued.first()
def size(self):
return self.enqueued.size() + self.dequeued.size()
