python 栈

栈的特点：先进后出

class Stack:
 
    def __init__(self):
        self.data = []
 
    def push(self, val):
        self.data.append(val)
 
    def pop(self):
        ret = self.data.pop()
        return ret
 
s = Stack()
s.push('love')
s.push('python')
print(s.pop())      # python