227. Basic Calculator II

class Solution:def calculate(self, s: str) -> int:it=iter(re.split(r'([\+\-\*\/])',s))last=ans=int(next(it))for op in it:n=int(next(it))if op in '+-':if op=='-':n=-nans+=nelse:if op=='*':n=last*nelse:n=int(last/n)ans=ans-last+nlast=nreturn ans

注意这个不用stack的写法