题解 | #表达式求值#

def calculate(expression):
    """
    计算给定算术表达式的值

    :param expression: 字符串描述的算术表达式
    :return: 计算结果
    """

    def parse_number():
        nonlocal i
        j = i
        while j < len(expression) and expression[j].isdigit():
            j += 1
        number = int(expression[i:j])
        i = j
        return number

    def parse_term():
        nonlocal i
        if i >= len(expression):
            return 0
        if expression[i] == "(":
            i += 1
            result = parse_expr()
            i += 1
            return result
        elif expression[i].isdigit():
            return parse_number()
        elif expression[i] == "-":
            i += 1
            return -parse_term()
        else:
            raise ValueError("Invalid expression")

    def parse_factor():
        nonlocal i
        left = parse_term()
        while i < len(expression) and expression[i] in "*/":
            operator = expression[i]
            i += 1
            right = parse_term()
            if operator == "*":
                left *= right
            else:
                left //= right
        return left

    def parse_expr():
        nonlocal i
        left = parse_factor()
        while i < len(expression) and expression[i] in "+-":
            operator = expression[i]
            i += 1
            right = parse_factor()
            if operator == "+":
                left += right
            else:
                left -= right
        return left

    # 解析表达式并计算结果
    i = 0
    return parse_expr()


# 示例用法
expression = input()
result = calculate(expression)
print(result)  # 输出 465