python实现分段计费模式下的每日费用计算

公司的面试题，已知每日用电量，求分段计费模式下计算每日的电费，当初做的时候遇到一个小坑，没考虑单日用电量跨越两个以上计费区间这种情况，

现在把这道题用新学的python实现出来并测试通过，算是功德圆满吧。

# coding:utf-8
import sys

MAX_INT = sys.maxsize
pricelist = []
priceIdx = 0


# 价格区间对象
class PriceRange(object):
    def __init__(self, price, min, max=MAX_INT):
        self.price = price
        self.min = min
        self.max = max


# 计算单日花费
def getOnedayCost(pre, total):
    global priceIdx
    if priceIdx == len(pricelist):
        priceIdx = priceIdx - 1
    price = pricelist[priceIdx].price
    max = pricelist[priceIdx].max

    if total > max:
        part1 = (max - pre) * price
        pre = max
        priceIdx = priceIdx + 1
        if priceIdx == len(pricelist):
            return part1 + (total - max) * price
        else:
            return part1 + getOnedayCost(pre, total)
    else:
        return (total - pre) * price


# 计算总花费
def caculate(usedlist):
    total = 0
    cost = []
    for used in usedlist:
        pre = total
        total = used + total
        cost.append(getOnedayCost(pre, total))
    return cost


# 校验价格区间
def verifyPriceBrand():
    if pricelist is None or len(pricelist) == 0:
        raise Exception("the price range can not be null!")
    tmp = pricelist[0].max
    for idx in range(1, len(pricelist)):
        if not pricelist[idx].min == tmp:
            raise Exception("the price range is not continuous!")
        tmp = pricelist[idx].max
    if tmp < MAX_INT:
        raise Exception("the price range is Incomplete !")
    print("pricelist is qualified.")
    return True


# 初始化价格区间
def initPriceBrand():
    pricelist.append(PriceRange(5, 0, 10))
    pricelist.append(PriceRange(6, 10, 20))
    pricelist.append(PriceRange(7, 20, 30))
    pricelist.append(PriceRange(8, 30, 40))
    pricelist.append(PriceRange(9, 40, 50))
    pricelist.append(PriceRange(10, 50))


if __name__ == "__main__":
    initPriceBrand()
    verifyPriceBrand()
    costlist = [5, 20, 80, 30, 10]
    print(caculate(costlist))