初始化棧:
class Stack(object):
def __init__(self):
self.stack = []
def push(self, value): # 進棧
self.stack.append(value)
def pop(self,num): #出棧
if self.stack:
self.stack.pop(num)
else:
raise LookupError('stack is empty!')
def is_empty(self): # 如果棧爲空
return not bool(self.stack)
def top(self):
#取出目前stack中最新的元素
return self.stack[-1]