python基于链表实现栈与队列

1）实现栈
代码实现：

class Node():
    def __init__(self,val,next=None):
        self.val=val
        self.next=next
class Stack():
    def __init__(self):
        self.head=None
        self.N=0
    def isEmpty(self):
        return self.N==0
    def size(self):
        return self.N
    def push(self, item):
        rear=self.head
        self.head=Node(item)
        self.head.item=item
        self.head.next=rear
        self.N+=1
    def pop(self):
        if  self.N==0:
            print("the stack'length is zero")
        else:
            item=self.head.val
            self.head=self.head.next
            return item
 
    def top(self):
        if self.N==0:
            print("the stack'length is zero")
        else: 
         return self.first.val
 
 
my_stack = Stack()
my_stack.pop()
my_stack.push('h')
my_stack.push('a')
print(my_stack.pop())
print(my_stack.pop())

输出：

a
h

2)实现队列
代码实现：

class Node():
    def __init__(self,item=None,next=None):
        self.item=item
        self.next=next
class _LinkListQueue(object):
    def __init__(self):
        self.first=None
        self.last=None
        self.N=0
    def isEmpty(self):
        return self.first is None
    def size(self):
        return self.N
    def enqueue(self,item):
        node=Node(item)
        if self.isEmpty():
            self.first=node
        else:
            self.last.next=node
        self.last=node
        self.N+=1
    def dequeue(self):
        if self.first is None:
            print( "this queue is empty")
        item = self.first.item
        self.first=self.first.next
        self.N-=1
        return item
    def __iter__(self):
        return self.first
my_queue =_LinkListQueue()
my_queue.enqueue('h')
my_queue.enqueue('a')
print(my_queue.dequeue())
print(my_queue.dequeue())
 

输出：

h
a