class Queue:
def __init__(self):
self._enqueue = Stack()
self._dequeue = Stack()
def is_empty(self):
return self._enqueue.is_empty() and self._dequeue.is_empty()
def size(self):
return self._dequeue.size() + self._enqueue.size()
def enqueue(self, item):
self._enqueue.push(item)
def dequeue(self):
if self._dequeue.is_empty():
while not self._enqueue.is_empty():
self._dequeue.push(self._enqueue.pop())
return self._dequeue.pop()
def stdout(self):
print('_enqueue')
self._enqueue.stdout()
print('_dequeue')
self._dequeue.stdout()
class StackQueue:
"""
Implementation of Queue using two Stacks.
"""
def __init__(self, limit=10):
self.limit = limit
self.stack_one = Stack(limit)
self.stack_two = Stack(limit)
def enqueue(self, item):
if self.isFull():
raise QueueOverflowError("Cannot insert item in a full queue.")
self.stack_one.push(item)
def _move_item_to_second_stack(self):
if self.stack_two.is_empty():
while not self.stack_one.is_empty():
self.stack_two.push(self.stack_one.pop())
def dequeue(self):
if self.isEmpty():
raise QueueUnderflowError(
"Cannot Remove an item from empty Queue.")
self._move_item_to_second_stack()
return self.stack_two.pop()
def peek(self):
self._move_item_to_second_stack()
return self.stack_two.peek()
def isEmpty(self):
return self.stack_one.is_empty() and self.stack_two.is_empty()
def isFull(self):
return (self.stack_one.size() + self.stack_two.size()) >= self.limit
def reverse_list(arr):
stack = Stack()
reversed = []
for item in arr:
stack.push(item)
while stack.size() > 0:
reversed.append(stack.pop())
return reversed