【每日一题20220718】实现计算器

兴趣爱好交流 每日一题
1

:mage:‍ 实现一个计算器，该计算器将可以在浏览器路由路径中写入的值作为单个字符串。然后它将结果作为数字（或错误消息）返回。

路由路径使用“/”符号，所以这不能在我们的计算器中。我们使用“$”符号作为除法运算符。

您将收到一个包含数字和运算符的任意长度的字符串：

  • ‘+’ = 添加
  • ‘-’ = 减法
  • ‘*’ = 相乘
  • ‘$’ = 除法

您的任务是分解字符串并使用此操作顺序计算表达式。（除法 => 乘法 => 减法 => 加法）

如果给您一个无效的输入（即除 之外.0123456789+-*$ 的任何字符），您应该返回错误消息：'400: Bad request'

记住：

  1. 操作次数不受限制
  2. 操作顺序是必须的
  3. 无eval 或等效功能
  4. 将数字转换为floats ，而不是整数

例子：

calculate('1+1')     => '2'
calculate('10$2')    => '5'
calculate('1.5*3')   => '4.5'

calculate('5+5+5+5') => '20'

calculate('1000$2.5$5+5-5+6$6') =>'81'

calculate('10-9p')   =>  '400: Bad request'

题目难度：一般
题目来源：https://www.codewars.com/kata/581bc0629ad9ff9873000316


def calculate(expression):
    # your code here


assert calculate("1.1") == 1.1
assert calculate("10+5") == 15
assert calculate("8-2") == 6
assert calculate("4*3") == 12
assert calculate("18$2") == 9
assert calculate("5+8-8*2$4") == 9
assert calculate("3x+1") == "400: Bad request"
2 
def calculate(expression: str):
    for i in expression:
        if i not in '.0123456789+-*$':
            return "400: Bad request"
    if '$' in expression:
        index1 = expression.index('$')
        left_index = index1 - 1
        while left_index >= 0:
            if expression[left_index].isdigit() or expression[left_index] == '.':
                left_index -= 1
            else:
                break
        left_index += 1
        right_index = index1 + 1
        while right_index < len(expression):
            if expression[right_index].isdigit() or expression[right_index] == '.':
                right_index += 1
            else:
                break
        right_index -= 1
        expression = expression[:left_index] + str(
            float(expression[left_index:index1]) / float(expression[index1 + 1:right_index + 1])) + expression[
                                                                                                    right_index + 1:]
    if '*' in expression:
        index2 = expression.index('*')
        left_index = index2 - 1
        while left_index >= 0:
            if expression[left_index].isdigit() or expression[left_index] == '.':
                left_index -= 1
            else:
                break
        left_index += 1
        right_index = index2 + 1
        while right_index < len(expression):
            if expression[right_index].isdigit() or expression[right_index] == '.':
                right_index += 1
            else:
                break
        right_index -= 1
        expression = expression[:left_index] + str(
            float(expression[left_index:index2]) * float(expression[index2 + 1:right_index + 1])) + expression[
                                                                                                    right_index + 1:]
    if '-' in expression:
        index3 = expression.index('-')
        left_index = index3 - 1
        while left_index >= 0:
            if expression[left_index].isdigit() or expression[left_index] == '.':
                left_index -= 1
            else:
                break
        left_index += 1
        right_index = index3 + 1
        while right_index < len(expression):
            if expression[right_index].isdigit() or expression[right_index] == '.':
                right_index += 1
            else:
                break
        right_index -= 1
        expression = expression[:left_index] + str(
            float(expression[left_index:index3]) - float(expression[index3 + 1:right_index + 1])) + expression[
                                                                                                    right_index + 1:]
    if '+' in expression:
        index4 = expression.index('+')
        left_index = index4 - 1
        while left_index >= 0:
            if expression[left_index].isdigit() or expression[left_index] == '.':
                left_index -= 1
            else:
                break
        left_index += 1
        right_index = index4 + 1
        while right_index < len(expression):
            if expression[right_index].isdigit() or expression[right_index] == '.':
                right_index += 1
            else:
                break
        right_index -= 1
        expression = expression[:left_index] + str(
            float(expression[left_index:index4]) + float(expression[index4 + 1:right_index + 1])) + expression[
                                                                                                    right_index + 1:]
    return float(expression) if int(str(expression).split('.')[1]) != 0 else int(float(expression))


assert calculate("1.1") == 1.1
assert calculate("10+5") == 15
assert calculate("8-2") == 6
assert calculate("4*3") == 12
assert calculate("18$2") == 9
assert calculate("5+8-8*2$4") == 9
assert calculate("3x+1") == "400: Bad request"