def delete_first(self):
deleted = self.head
if self.head:
self.head = self.head.next
deleted.next = None
return deleted
class Element(object):
def __init__(self, value):
self.value = value
self.next = None
class LinkedList(object):
def __init__(self, head=None):
self.head = head
def append(self, new_element):
current = self.head
if self.head:
while current.next:
current = current.next
current.next = new_element
else:
self.head = new_element
def insert_first(self, new_element):
new_element.next = self.head
self.head = new_element
def delete_first(self):
if self.head:
deleted_element = self.head
temp = deleted_element.next
self.head = temp
return deleted_element
else:
return None
class Stack(object):
def __init__(self,top=None):
self.ll = LinkedList(top)
def push(self, new_element):
self.ll.insert_first(new_element)
def pop(self):
return self.ll.delete_first()
