题解 | #表达式求值#

def calculate(s: str) -> int:
    def helper(s: list) -> int:
        stack = []
        num = 0
        sign = "+"

        while len(s) > 0:
            c = s.pop(0)
            if c.isdigit():
                num = num * 10 + int(c)
            if c == "(":
                num = helper(s)
            if len(s) == 0 or c in "+-*/)":
                if sign == "+":
                    stack.append(num)
                elif sign == "-":
                    stack.append(-num)
                elif sign == "*":
                    stack.append(stack.pop() * num)
                elif sign == "/":
                    stack.append(int(stack.pop() / num))  # 确保整数除法向下取整
                num = 0
                sign = c
            if c == ")":
                break
        return sum(stack)

    # 为了使用pop(0)操作，将字符串转换成列表
    return helper(list(s))


# 输入字符串
s = input().replace(" ", "")  # 删除空格
# 输出计算结果
print(calculate(s))