MAX_SIZE = 100

classMyStack1(object):"""模拟栈"""

def __init__(self):

self.items=[]

self.size=0defis_empty(self):"""判断是否为空"""

return self.size ==0defsize(self):"""返回栈的大小"""

returnself.sizedefpush(self, item):"""压栈(加入元素)"""self.items.append(item)

self.size+= 1

defpop(self):"""弹栈(弹出元素)"""

if self.size < MAX_SIZE and self.size >=0:

self.size-= 1

returnself.items.pop()else:print("栈已经为空")returnNonedefpeek(self):if notself.is_empty():return self.items[self.size-1]else:returnNonedef __str__(self):returnstr(self.items)classMyStack2(object):"""模拟栈"""

def __init__(self):

self.items=[]

self.size=0defis_empty(self):"""判断是否为空"""

return self.size ==0defsize(self):"""返回栈的大小"""

if self.size <=MAX_SIZE:returnself.sizedefpush(self, item):"""压栈(加入元素)"""

if self.size <=MAX_SIZE:

self.items.insert(0, item)

self.size+= 1

defpop(self):"""弹栈(弹出元素)"""

if self.size > 0 and self.size <=MAX_SIZE:

self.size-= 1

returnself.items.pop(0)else:print("栈已经为空")returnNonedefpeek(self):"""返回栈顶元素"""

if notself.is_empty():returnself.items[0]else:returnNonedef __str__(self):returnstr(self.items)classNode():def __init__(self, data, next=None):

self.data=data

self.next=nextdef __repr__(self):returnstr(self.data)classNodeStack():def __init__(self):

self.node=Node(None)

self.head=self.node

self.size=0defis_empty(self):return self.size ==0defget_size(self):returnself.sizedefpush(self, data):

node=Node(data)

node.next=self.head.next

self.head.next=node

self.size+= 1

defpop(self):if notself.is_empty():

current=self.head.nextif self.get_size() == 1:

self.head.next=Noneelse:

self.head.next=self.head.next.next

self.size-= 1

returncurrent.dataelse:raise IndexError('pop from a empty stack')defpeek(self):if notself.is_empty():returnself.head.next.dataelse:raise IndexError('stack is empty')def __repr__(self):

stack_list=[]

current=self.headwhile current.next is notNone:

stack_list.append(current.next.data)

current=current.nextreturnstr(stack_list)__str__ = __repr__

deftest(obj):

i=obj()for x in range(0,6):

i.push(x)print(i)

i.pop()print(i, i.peek(), i.size)if __name__ == "__main__":

test(MyStack1)

test(MyStack2)

test(NodeStack)