class Stack:
def __init__(self):
self.size = 0
# Why is our DLL a good choice to store our elements?
# we will be adding and subtracting based on LIFO
self.storage = DoublyLinkedList()
def push(self, value):
# add to the top of the stack, aka the tail
# increment size by 1
self.size += 1
self.storage.add_to_tail(value)
def pop(self):
# check if size > 0
# if true:
# remove from the top of the stack, aka the tail
# decrement size by 1
# else return None
if self.size > 0:
self.size -= 1
return self.storage.remove_from_tail()
else:
return None
def len(self):
return self.size
class Queue:
def __init__(self):
self.size = 0
# Why is our DLL a good choice to store our elements?
# it has directional pointers so we know
# where something is in the 'queue'
self.storage = DoublyLinkedList()
def enqueue(self, value):
# take the dll
# run add to tail and pass it value
self.storage.add_to_head(value)
self.size += 1
def dequeue(self):
# check if size > 0
# if yes, dequeue
# take the dll
# run add remove from tail
# decrement size by 1
# if not, return None
if self.size > 0:
self.size -= 1
return self.storage.remove_from_tail()
else:
return None
def len(self):
# return size of queue
return self.size
def __init__(self):
self.size = 0
# Why is our DLL a good choice to store our elements?
# we will be adding and subtracting based on LIFO
self.storage = DoublyLinkedList()
def __init__(self):
self.size = 0
# Why is our DLL a good choice to store our elements?
# it has directional pointers so we know
# where something is in the 'queue'
self.storage = DoublyLinkedList()