Question

每个子列表始终按以下顺序包含三个元素：

会员类型：'Student'，'Faculty'或'Visitor'之一的字符串。
汽车类型：'Coupe'，'Sedan'，'SUV'或'Hybrid'之一的字符串。
持续时间：借车的小时数根据会员类型，汽车可提供长达一定时间的免费服务：
'Student'：前三个小时免费
'Faculty'：前两个小时免费
'Visitor'：第一个小时是免费的

免费服务结束后，会员会根据他们租用的汽车类型收取费用：

轿车：每小时10美元
Coupe：每小时12美元
SUV：每小时13美元
混合动力：每小时15美元

在索引0处存储Sedans产生的总收入。在索引1存储Coupes产生的总收入。在索引2处存储SUV产生的总收入。在指数3处存储了Hybrids产生的总收入。

def car_rental(rentals):
    car_type = [0, 0, 0, 0]
    for rental in rentals:
        if rental == 'Student' and car_type == "Sedan" and hours > 3:
            income = 10 * (hours - 3)
            car_type[0] += income
    for rental in rentals:
        if rental == 'Faculty' and car_type == "Sedan" and hours > 2:
           income = 10 * (hours - 2)
           car_type[0] += income
    for rental in rentals:
        if rental == 'Visitor' and car_type == "Sedan" and hours > 1:
            income = 10 * (hours - 1)
            car_type[0] += income
    for rental in rentals:
        if rental == 'Student' and car_type == "Coupe" and hours > 3:
           income = 12 * (hours - 3)
           car_type[1] += income
    for rental in rentals:
        if rental == 'Faculty' and car_type == "Coupe" and hours > 2:
           income = 12 * (hours - 2)
           car_type[1] += income
    for rental in rentals:
        if rental == 'Visitor' and car_type == "Coupe" and hours > 1:
           income = 12 * (hours - 1)
           car_type[1] += income
    for rental in rentals:
        if rental == 'Student' and car_type == "SUV" and hours > 3:
           income = 13 * (hours - 3)
           car_type[2] += income
    for rental in rentals:
        if rental == 'Faculty' and car_type == "SUV" and hours > 2:
           income = 13 * (hours - 2)
           car_type[2] += income
    for rental in rentals:
        if rental == 'Visitor' and car_type == "SUV" and hours > 1:
           income = 13 * (hours - 1)
           car_type[2] += income
    for rental in rentals:
        if rental == 'Student' and car_type == "Hybrid" and hours > 3:
           income = 15 * (hours - 3)
           car_type[3] += income
    for rental in rentals:
        if rental == 'Faculty' and car_type == "Hybrid" and hours > 2:
           income = 15 * (hours - 2)
           car_type[3] += income
    for rental in rentals:
        if rental == 'Visitor' and car_type == "Hybrid" and hours > 1:
           income = 15 * (hours - 1)
           car_type[3] += income

    return car_type

经过测试：

print("Testing car_rental() with rentals = [['Student','Coupe',4],['Faculty','Coupe',4],['Visitor','Coupe',4]]: " +
      str(car_rental([['Student', 'Coupe', 4], ['Faculty', 'Coupe', 4], ['Visitor', 'Coupe', 4]])))
print("Testing car_rental() with rentals = [['Student','Coupe',4],['Faculty','SUV',4],['Visitor','Hybrid',4],['Visitor','Sedan',4]]: " +
      str(car_rental([['Student', 'Coupe', 4], ['Faculty', 'SUV', 4], ['Visitor', 'Hybrid', 4], ['Visitor', 'Sedan', 4]])))
print("Testing car_rental() with rentals = [['Student','Coupe',3],['Faculty','SUV',2],['Visitor','Hybrid',1],['Visitor','Sedan',4]]: " +
      str(car_rental([['Student', 'Coupe', 3], ['Faculty', 'SUV', 2], ['Visitor', 'Hybrid', 1], ['Visitor', 'Sedan', 4]])))
print()

Answer 1

问题在于您引用传递给函数的rentals参数的元素的方式。特别是在每个for rental in rentals:循环中，rental变量本身也是list，您需要使用[]索引表示法引用其内容。

这是您的代码的固定版本：

def car_rental(rentals):
    car_type = [0, 0, 0, 0]
    for rental in rentals:
        if rental[0] == 'Student' and rental[1] == "Sedan" and rental[2] > 3:
            income = 10 * (rental[2] - 3)
            car_type[0] += income
    for rental in rentals:
        if rental[0] == 'Faculty' and rental[1] == "Sedan" and rental[2] > 2:
           income = 10 * (rental[2] - 2)
           car_type[0] += income
    for rental in rentals:
        if rental[0] == 'Visitor' and rental[1] == "Sedan" and rental[2] > 1:
            income = 10 * (rental[2] - 1)
            car_type[0] += income
    for rental in rentals:
        if rental[0] == 'Student' and rental[1] == "Coupe" and rental[2] > 3:
           income = 12 * (rental[2] - 3)
           car_type[1] += income
    for rental in rentals:
        if rental[0] == 'Faculty' and rental[1] == "Coupe" and rental[2] > 2:
           income = 12 * (rental[2] - 2)
           car_type[1] += income
    for rental in rentals:
        if rental[0] == 'Visitor' and rental[1] == "Coupe" and rental[2] > 1:
           income = 12 * (rental[2] - 1)
           car_type[1] += income
    for rental in rentals:
        if rental[0] == 'Student' and rental[1] == "SUV" and rental[2] > 3:
           income = 13 * (rental[2] - 3)
           car_type[2] += income
    for rental in rentals:
        if rental[0] == 'Faculty' and rental[1] == "SUV" and rental[2] > 2:
           income = 13 * (rental[2] - 2)
           car_type[2] += income
    for rental in rentals:
        if rental[0] == 'Visitor' and rental[1] == "SUV" and rental[2] > 1:
           income = 13 * (rental[2] - 1)
           car_type[2] += income
    for rental in rentals:
        if rental[0] == 'Student' and rental[1] == "Hybrid" and rental[2] > 3:
           income = 15 * (rental[2] - 3)
           car_type[3] += income
    for rental in rentals:
        if rental[0] == 'Faculty' and rental[1] == "Hybrid" and rental[2] > 2:
           income = 15 * (rental[2] - 2)
           car_type[3] += income
    for rental in rentals:
        if rental[0] == 'Visitor' and rental[1] == "Hybrid" and rental[2] > 1:
           income = 15 * (rental[2] - 1)
           car_type[3] += income

    return car_type

print("Testing car_rental() with rentals = "
      "[['Student','Coupe',4], ['Faculty','Coupe',4], ['Visitor','Coupe',4]]: " +
      str(car_rental([['Student', 'Coupe', 4], ['Faculty', 'Coupe', 4], ['Visitor', 'Coupe', 4]])))

print("Testing car_rental() with rentals = "
      "[['Student','Coupe',4], ['Faculty','SUV',4], ['Visitor','Hybrid',4], ['Visitor','Sedan',4]]: " +
      str(car_rental([['Student', 'Coupe', 4], ['Faculty', 'SUV', 4], ['Visitor', 'Hybrid', 4], ['Visitor', 'Sedan', 4]])))

print("Testing car_rental() with rentals = "
      "[['Student','Coupe',3],['Faculty','SUV',2],['Visitor','Hybrid',1],['Visitor','Sedan',4]]: " +
      str(car_rental([['Student', 'Coupe', 3], ['Faculty', 'SUV', 2], ['Visitor', 'Hybrid', 1], ['Visitor', 'Sedan', 4]])))

输出：

Testing car_rental() with rentals = [['Student','Coupe',4], ['Faculty','Coupe',4], ['Visitor','Coupe',4]]: [0, 72, 0, 0]

Testing car_rental() with rentals = [['Student','Coupe',4], ['Faculty','SUV',4], ['Visitor','Hybrid',4], ['Visitor','Sedan',4]]: [30, 12, 26, 45]

Testing car_rental() with rentals = [['Student','Coupe',3],['Faculty','SUV',2],['Visitor','Hybrid',1],['Visitor','Sedan',4]]: [30, 0, 0, 0]

更好的解决方法是在每个嵌套rental循环开头为for子列表的每个元素提供可读名称。这些方面的东西：

def car_rental(rentals):
    car_type = [0, 0, 0, 0]
    for customer, style, hours in rentals:
        if customer == 'Student' and style == "Sedan" and hours > 3:
            income = 10 * (hours - 3)
            car_type[0] += income
    for customer, style, hours in rentals:
        if customer == 'Faculty' and style == "Sedan" and hours > 2:
           income = 10 * (hours - 2)
           car_type[0] += income
    etc ...

除此之外，您还可以将所有if语句放在一个大的for rental in rentals:循环中。这会更快，并且需要稍微缩短所需的代码量：

def car_rental(rentals):
    car_type = [0, 0, 0, 0]
    for customer, style, hours in rentals:
        if customer == 'Student' and style == "Sedan" and hours > 3:
            income = 10 * (hours - 3)
            car_type[0] += income

        if customer == 'Faculty' and style == "Sedan" and hours > 2:
           income = 10 * (hours - 2)
           car_type[0] += income

        etc ...

为什么这个函数没有返回任何值？

1 个答案: