有一款AI学习机的产品针对小学数据方面可以锻炼学生算术运算的能力。假设你作为学习机该功能的开发人员需要实现对输入法的算术表达式按照运算法则进行求值表达式字符串只包含：+-非负整数空格。当整除除法不能整除时需向上取整。请帮我写出对应的python代码

可以使用栈和逆波兰表达式来实现对算术表达式的求值。以下是对应的Python代码：

def calculate(expression):
    # 将表达式转换为逆波兰表达式
    def convert_to_rpn(expression):
        operators = {'+': 1, '-': 1, '*': 2, '/': 2}
        rpn = []
        stack = []
        i = 0
        while i < len(expression):
            if expression[i].isdigit():
                num = ''
                while i < len(expression) and expression[i].isdigit():
                    num += expression[i]
                    i += 1
                rpn.append(int(num))
            elif expression[i] == '(':
                stack.append('(')
                i += 1
            elif expression[i] == ')':
                while stack and stack[-1] != '(':
                    rpn.append(stack.pop())
                stack.pop()
                i += 1
            elif expression[i] in operators:
                while stack and stack[-1] != '(' and operators[expression[i]] <= operators.get(stack[-1], 0):
                    rpn.append(stack.pop())
                stack.append(expression[i])
                i += 1
            else:
                i += 1
        while stack:
            rpn.append(stack.pop())
        return rpn

    # 计算逆波兰表达式的值
    def evaluate_rpn(rpn):
        stack = []
        for token in rpn:
            if isinstance(token, int):
                stack.append(token)
            else:
                b = stack.pop()
                a = stack.pop()
                if token == '+':
                    stack.append(a + b)
                elif token == '-':
                    stack.append(a - b)
                elif token == '*':
                    stack.append(a * b)
                elif token == '/':
                    stack.append(-(-a // b))  # 向上取整的整除运算
        return stack[0]

    rpn = convert_to_rpn(expression)
    return evaluate_rpn(rpn)

expression = input("请输入算术表达式：")
result = calculate(expression)
print("计算结果为：", result)

这段代码先将输入的算术表达式转换为逆波兰表达式，再通过栈来计算逆波兰表达式的值。其中，convert_to_rpn函数用于将算术表达式转换为逆波兰表达式，evaluate_rpn函数用于计算逆波兰表达式的值。最后，通过调用calculate函数来获得算术表达式的结果