用python实现栈和队列

class stack():
def __init__(self):
self.stack=[]
def empty(self):
return self.stack ==[]
def push(self,data):
self.stack.append(data)
return self.stack
def pop(self):
if self.empty():
return None
else:
return self.stack.pop(-1)
def top(self):
if self.empty():
return None
else:
return self.stack(-1)
def length(self):
return len(self.stack)

class queque():
def __init__(self):
self.queque=[]
def empty(self):
return self.queque==[]
def enqueque(self,data):
self.queque.append(data)
return self.queque
def dequeque(self):
if self.empty():
return None
else:
return self.queque.pop(0)
def head(self):
if self.empty():
return None
else:
return self.queque[0]
def length(self):
return len(self.queque)