class Stack: def __init__(self): self.storage = LinkedList() def __repr__(self): return f"{self.storage}" def __len__(self): return len(self.storage) def push(self, value): self.storage.add_to_tail(value) def pop(self): if len(self.storage) > 0: return self.storage.remove_from_tail()
class Stack: def __init__(self): self.size = 0 self.storage = LinkedList() def __len__(self): return self.size def push(self, value): self.size += 1 self.storage.add_to_end(value) def pop(self): if self.size != 0: self.size -= 1 return self.storage.remove_from_tail() else: return None
class Stack: def __init__(self): self.size = 0 self.storage = LinkedList() def __len__(self): if self.size >= 0: return self.size else: return 0 def push(self, value): self.storage.add_to(value) self.size += 1 def pop(self): if self.size > 0: value = self.storage.remove_from_tail() self.size -= 1 return value