仿写一个类实现栈

仿写自博客 http://www.cnblogs.com/chongyou/p/7099692.html

class Node(object):

    def __init__(self,n):

        self.val = n

        self.next = None

class mystack(object):

    def __init__(self):

        self.top = None

    def push(self,x):

        n = Node(x)

        n.next = self.top

        self.top = n

        return n.val

    def pop(self):

        if self.top:

            tmp = self.top.val

            self.top = self.top.next

            return tmp

        return None

    def peek(self):

        if self.top:

            return self.top.val

        return None

if __name__=="__main__":

    s = mystack()

    s.push('程劲')

    s.push('陈培昌')

    s.push('徐晓冬')

    s.push('厉智')

    print(s.pop())

    print(s.pop())

    print(s.pop())

    print(s.pop())