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Курс във Факултета по Математика и Информатика към СУ

Решение на Трета задача от Стефан Кънев

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Към профила на Стефан Кънев

Резултати

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  • 19 успешни тест(а)
  • 0 неуспешни тест(а)

Код

require 'bigdecimal'
require 'bigdecimal/util'
module Promotions
def self.for(hash)
name, options = hash.first
case name
when :get_one_free then GetOneFree.new options
when :package then PackageDiscount.new *options.first
when :threshold then ThresholdDiscount.new *options.first
else NoPromotion.new
end
end
class GetOneFree
def initialize(nth_item_free)
@nth_item_free = nth_item_free
end
def discount(count, price)
(count / @nth_item_free) * price
end
def name
"buy #{@nth_item_free - 1}, get 1 free"
end
end
class PackageDiscount
def initialize(size, percent)
@size = size
@percent = percent
end
def discount(count, price)
multiplier = @percent / '100'.to_d
package_discount = price * multiplier * @size
packages = count / @size
package_discount * packages
end
def name
'get %d%% off for every %s' % [@percent, @size]
end
end
class ThresholdDiscount
def initialize(threshold, percent)
@threshold = threshold
@percent = percent
end
def discount(count, price)
multiplier = @percent / '100'.to_d
item_discount = price * multiplier
items_above_threshold = [count - @threshold, 0].max
items_above_threshold * item_discount
end
def name
suffix = {1 => 'st', 2 => 'nd', 3 => 'rd'}.fetch @threshold, 'th'
'%2.f%% off of every after the %d%s' % [@percent, @threshold, suffix]
end
end
class NoPromotion
def discount(count, price)
0
end
def name
''
end
end
end
module Coupon
def self.build(name,type)
case type.keys.first
when :percent then PercentOff.new name, type[:percent]
when :amount then AmountOff.new name, type[:amount]
else raise "Unknown coupon: #{type.inspect}"
end
end
class PercentOff
attr_reader :name
def initialize(name, percent)
@name = name
@percent = percent
end
def discount(order_price)
(@percent / '100'.to_d) * order_price
end
def description
"%d%% off" % @percent
end
end
class AmountOff
attr_reader :name
def initialize(name, amount)
@name = name
@amount = amount
end
def discount(order_price)
[order_price, @amount].min
end
def description
"%-5.2f off" % @amount
end
end
class NilCoupon
attr_reader :name
def discount(order_price)
0
end
end
end
class Product
attr_reader :name, :price, :promotion
def initialize(name, price, promotion)
raise "Name should be at most 40 characters" unless name.length <= 40
raise "Only prices betwee 0.01 and 999.99 allowed" unless 0 < price and price < 1000
@name = name
@price = price
@promotion = promotion
end
end
class Inventory
def initialize
@products = []
@coupons = []
end
def new_cart
ShoppingCart.new self
end
def register(name, price, options = {})
price = price.to_d
promotion = Promotions.for options
@products << Product.new(name, price, promotion)
end
def register_coupon(name, type)
@coupons << Coupon.build(name, type)
end
def [](name)
@products.detect { |product| product.name == name } or raise 'Unexisting product'
end
def coupon(name)
@coupons.detect { |coupon| coupon.name == name } or Coupon::NilCoupon.new
end
end
class ShoppingCart
attr_reader :items, :coupon
def initialize(inventory)
@inventory = inventory
@items = []
@coupon = Coupon::NilCoupon.new
end
def add(product_name, count = 1)
product = @inventory[product_name]
item = @items.detect { |item| item.product == product }
if item
item.count += count
else
@items << LineItem.new(product, count)
end
end
def use(coupon_name)
@coupon = @inventory.coupon coupon_name
end
def total
items_price - coupon_discount
end
def items_price
@items.map(&:price).inject(&:+)
end
def coupon_discount
@coupon.discount items_price
end
def invoice
InvoicePrinter.new(self).to_s
end
end
class LineItem
attr_reader :product
attr_accessor :count
def initialize(product, count)
@product = product
@count = 0
increase count
end
def increase(count)
raise 'You have to add at least one item' if count <= 0
raise 'Maximum 99 items of each product can be bought' if count + @count > 99
@count += count
end
def product_name
@product.name
end
def price
price_without_discount - discount
end
def price_without_discount
product.price * count
end
def discount
product.promotion.discount(count, product.price)
end
def discount_name
product.promotion.name
end
def discounted?
not discount.zero?
end
end
class InvoicePrinter
def initialize(cart)
@cart = cart
end
def to_s
@output = ""
print_header
print_items
print_total
@output
end
private
def print_header
print_line
print 'Name', 'qty', 'price'
print_line
end
def print_items
@cart.items.each do |item|
print item.product_name, item.count, amount(item.price_without_discount)
print " (#{item.discount_name})", '', amount(-item.discount) if item.discounted?
end
if @cart.coupon_discount.nonzero?
name = "Coupon #{@cart.coupon.name} - #{@cart.coupon.description}"
print name, '', amount(-@cart.coupon_discount)
end
end
def print_total
print_line
print 'TOTAL', '', amount(@cart.total)
print_line
end
def print_line
@output << "+------------------------------------------------+----------+\n"
end
def print(*args)
@output << "| %-40s %5s | %8s |\n" % args
end
def amount(decimal)
"%5.2f" % decimal
end
end

Лог от изпълнението

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Finished in 0.56584 seconds
19 examples, 0 failures

История (1 версия и 3 коментара)

Стефан обнови решението на 31.10.2011 22:44 (преди около 13 години)

+require 'bigdecimal'
+require 'bigdecimal/util'
+
+module Promotions
+ def self.for(hash)
+ name, options = hash.first
+
+ case name
+ when :get_one_free then GetOneFree.new options
+ when :package then PackageDiscount.new *options.first
+ when :threshold then ThresholdDiscount.new *options.first
+ else NoPromotion.new
+ end
+ end
+
+ class GetOneFree
+ def initialize(nth_item_free)
+ @nth_item_free = nth_item_free
+ end
+
+ def discount(count, price)
+ (count / @nth_item_free) * price
+ end
+
+ def name
+ "buy #{@nth_item_free - 1}, get 1 free"
+ end
+ end
+
+ class PackageDiscount
+ def initialize(size, percent)
+ @size = size
+ @percent = percent
+ end
+
+ def discount(count, price)
+ multiplier = @percent / '100'.to_d
+ package_discount = price * multiplier * @size
+ packages = count / @size
+
+ package_discount * packages
+ end
+
+ def name
+ 'get %d%% off for every %s' % [@percent, @size]
+ end
+ end
+
+ class ThresholdDiscount
+ def initialize(threshold, percent)
+ @threshold = threshold
+ @percent = percent
+ end
+
+ def discount(count, price)
+ multiplier = @percent / '100'.to_d
+ item_discount = price * multiplier
+ items_above_threshold = [count - @threshold, 0].max
+
+ items_above_threshold * item_discount
+ end
+
+ def name
+ suffix = {1 => 'st', 2 => 'nd', 3 => 'rd'}.fetch @threshold, 'th'
+ '%2.f%% off of every after the %d%s' % [@percent, @threshold, suffix]
+ end
+ end
+
+ class NoPromotion
+ def discount(count, price)
+ 0
+ end
+
+ def name
+ ''
+ end
+ end
+end
+
+module Coupon
+ def self.build(name,type)
+ case type.keys.first
+ when :percent then PercentOff.new name, type[:percent]
+ when :amount then AmountOff.new name, type[:amount]
+ else raise "Unknown coupon: #{type.inspect}"
+ end
+ end
+
+ class PercentOff
+ attr_reader :name
+
+ def initialize(name, percent)
+ @name = name
+ @percent = percent
+ end
+
+ def discount(order_price)
+ (@percent / '100'.to_d) * order_price
+ end
+
+ def description
+ "%d%% off" % @percent
+ end
+ end
+
+ class AmountOff
+ attr_reader :name
+
+ def initialize(name, amount)
+ @name = name
+ @amount = amount
+ end
+
+ def discount(order_price)
+ [order_price, @amount].min
+ end
+
+ def description
+ "%-5.2f off" % @amount
+ end
+ end
+
+ class NilCoupon
+ attr_reader :name
+
+ def discount(order_price)
+ 0
+ end
+ end
+end
+
+class Product
+ attr_reader :name, :price, :promotion
+
+ def initialize(name, price, promotion)
+ raise "Name should be at most 40 characters" unless name.length <= 40
+ raise "Only prices betwee 0.01 and 999.99 allowed" unless 0 < price and price < 1000
+
+ @name = name
+ @price = price
+ @promotion = promotion
+ end
+end
+
+class Inventory
+ def initialize
+ @products = []
+ @coupons = []
+ end
+
+ def new_cart
+ ShoppingCart.new self
+ end
+
+ def register(name, price, options = {})
+ price = price.to_d
+ promotion = Promotions.for options
+
+ @products << Product.new(name, price, promotion)
+ end
+
+ def register_coupon(name, type)
+ @coupons << Coupon.build(name, type)
+ end
+
+ def [](name)
+ @products.detect { |product| product.name == name } or raise 'Unexisting product'
+ end
+
+ def coupon(name)
+ @coupons.detect { |coupon| coupon.name == name } or Coupon::NilCoupon.new
+ end
+end
+
+class ShoppingCart
+ attr_reader :items, :coupon
+
+ def initialize(inventory)
+ @inventory = inventory
+ @items = []
+ @coupon = Coupon::NilCoupon.new
+ end
+
+ def add(product_name, count = 1)
+ product = @inventory[product_name]
+ item = @items.detect { |item| item.product == product }
+
+ if item
+ item.count += count
+ else
+ @items << LineItem.new(product, count)
+ end
+ end
+
+ def use(coupon_name)
+ @coupon = @inventory.coupon coupon_name
+ end
+
+ def total
+ items_price - coupon_discount
+ end
+
+ def items_price
+ @items.map(&:price).inject(&:+)
+ end
+
+ def coupon_discount
+ @coupon.discount items_price
+ end
+
+ def invoice
+ InvoicePrinter.new(self).to_s
+ end
+end
+
+class LineItem
+ attr_reader :product
+ attr_accessor :count
+
+ def initialize(product, count)
+ @product = product
+ @count = 0
+
+ increase count
+ end
+
+ def increase(count)
+ raise 'You have to add at least one item' if count <= 0
+ raise 'Maximum 99 items of each product can be bought' if count + @count > 99
+ @count += count
+ end
+
+ def product_name
+ @product.name
+ end
+
+ def price
+ price_without_discount - discount
+ end
+
+ def price_without_discount
+ product.price * count
+ end
+
+ def discount
+ product.promotion.discount(count, product.price)
+ end
+
+ def discount_name
+ product.promotion.name
+ end
+
+ def discounted?
+ not discount.zero?
+ end
+end
+
+class InvoicePrinter
+ def initialize(cart)
+ @cart = cart
+ end
+
+ def to_s
+ @output = ""
+ print_header
+ print_items
+ print_total
+ @output
+ end
+
+ private
+
+ def print_header
+ print_line
+ print 'Name', 'qty', 'price'
+ print_line
+ end
+
+ def print_items
+ @cart.items.each do |item|
+ print item.product_name, item.count, amount(item.price_without_discount)
+ print " (#{item.discount_name})", '', amount(-item.discount) if item.discounted?
+ end
+
+ if @cart.coupon_discount.nonzero?
+ name = "Coupon #{@cart.coupon.name} - #{@cart.coupon.description}"
+ print name, '', amount(-@cart.coupon_discount)
+ end
+ end
+
+ def print_total
+ print_line
+ print 'TOTAL', '', amount(@cart.total)
+ print_line
+ end
+
+ def print_line
+ @output << "+------------------------------------------------+----------+\n"
+ end
+
+ def print(*args)
+ @output << "| %-40s %5s | %8s |\n" % args
+ end
+
+ def amount(decimal)
+ "%5.2f" % decimal
+ end
+end