【Kata Daily 190909】The Supermarket Queue（超市队列）

题目：

There is a queue for the self-checkout tills at the supermarket. Your task is write a function to calculate the total time required for all the customers to check out!

input

• customers: an array of positive integers representing the queue. Each integer represents a customer, and its value is the amount of time they require to check out.
• n: a positive integer, the number of checkout tills.

output

The function should return an integer, the total time required.

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Important

Please look at the examples and clarifications below, to ensure you understand the task correctly :)

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Examples

queue_time([5,3,4], 1)
# should return 12
# because when n=1, the total time is just the sum of the times

queue_time([10,2,3,3], 2)
# should return 10
# because here n=2 and the 2nd, 3rd, and 4th people in the 
# queue finish before the 1st person has finished.

queue_time([2,3,10], 2)
# should return 12

Clarifications

• There is only ONE queue serving many tills, and
• The order of the queue NEVER changes, and
• The front person in the queue (i.e. the first element in the array/list) proceeds to a till as soon as it becomes free.

N.B. You should assume that all the test input will be valid, as specified above.

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题目大意：有客户队列customer和收银机器n，你要算出最少的时间

解题方法：

看一下网友的解题算法：

def queue_time(customers, n):
    l = [0]*n
    for i in customers:
        l[l.index(min(l))] += i
    return max(l)

解读：根据n的大小造出l的长度，找出l中最小的那个的索引，让此值加i

还有另外一种：

def queue_time(customers, n):
    qn = [0] * n
    for c in customers:
        qn = sorted(qn)
        qn[0] += c
    return max(qn)

 

知识点：

1、快速建立一个指定长度的list，L = [0]*n。

2、sort()和sorted()的区别：

　　sort()是作用于list上面，是在原来list上进行操作修改，用法是：L.sort()。sorted是作用于一个可迭代对象，返回来的是一个新的对象，用法是：sorted(iterable)。

3、找出某个值所在的索引。使用L.index(n)，找出n在L中的索引。