表达式求值

# 中缀表达式转为后缀表达式
def func1(s: str):
    s1temp = []
    s2temp = []
    for i in s.split():
        if i.isdigit():
            s1temp.append(i)
        elif i in '*/+-':
            s2temp.append(i)
        elif i in ')':
            s1temp.append(s2temp.pop())
    return " ".join(s1temp)


# 后缀表达式求值
def func2(s: str):
    s1temp = []
    for i in s.split():
        if i.isdigit():
            s1temp.append(i)
        else:
            s2 = s1temp.pop()
            s1 = s1temp.pop()
            s1temp.append(eval(f'{s1}{i}{s2}'))
    return s1temp[0]


if __name__ == '__main__':
    s1 = '( 2 + ( ( 4 * 8 ) / ( 2 + 2 ) ) )'  # 2 4 8 * 2 2 + / +
    s2 = '23 22 + 2 4 * -'  # 23 + 22 - 2 * 4
    s3 = '0 9 -'
    print(func1(s1))
    print(func2(s2))
    print(func2(s3))

标签：__,s2,s1,表达式,求值,s1temp,append
来源： https://www.cnblogs.com/bigcoolcool/p/16209550.html