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Contents

# Book Store

To try and encourage more sales of different books from a popular 5 book
series, a bookshop has decided to offer discounts on multiple book purchases.

One copy of any of the five books costs $8.

If, however, you buy two different books, you get a 5%
discount on those two books.

If you buy 3 different books, you get a 10% discount.

If you buy 4 different books, you get a 20% discount.

If you buy all 5, you get a 25% discount.

Note: that if you buy four books, of which 3 are
different titles, you get a 10% discount on the 3 that
form part of a set, but the fourth book still costs $8.

Your mission is to write a piece of code to calculate the
price of any conceivable shopping basket (containing only
books of the same series), giving as big a discount as
possible.

For example, how much does this basket of books cost?

- 2 copies of the first book
- 2 copies of the second book
- 2 copies of the third book
- 1 copy of the fourth book
- 1 copy of the fifth book

One way of grouping these 8 books is:

- 1 group of 5 --> 25% discount (1st,2nd,3rd,4th,5th)
- +1 group of 3 --> 10% discount (1st,2nd,3rd)

This would give a total of:

- 5 books at a 25% discount
- +3 books at a 10% discount

Resulting in:

- 5 x (8 - 2.00) == 5 x 6.00 == $30.00
- +3 x (8 - 0.80) == 3 x 7.20 == $21.60

For a total of $51.60

However, a different way to group these 8 books is:

- 1 group of 4 books --> 20% discount  (1st,2nd,3rd,4th)
- +1 group of 4 books --> 20% discount  (1st,2nd,3rd,5th)

This would give a total of:

- 4 books at a 20% discount
- +4 books at a 20% discount

Resulting in:

- 4 x (8 - 1.60) == 4 x 6.40 == $25.60
- +4 x (8 - 1.60) == 4 x 6.40 == $25.60

For a total of $51.20

And $51.20 is the price with the biggest discount.


## Source

Inspired by the harry potter kata from Cyber-Dojo. [http://cyber-dojo.org](http://cyber-dojo.org)

## Submitting Incomplete Solutions
It's possible to submit an incomplete solution so you can see how others have completed the exercise.

Version data entries

74 entries across 74 versions & 1 rubygems

Version Path
trackler-2.2.1.180 tracks/csharp/exercises/book-store/README.md
trackler-2.2.1.179 tracks/csharp/exercises/book-store/README.md
trackler-2.2.1.178 tracks/csharp/exercises/book-store/README.md
trackler-2.2.1.177 tracks/csharp/exercises/book-store/README.md
trackler-2.2.1.176 tracks/csharp/exercises/book-store/README.md
trackler-2.2.1.175 tracks/csharp/exercises/book-store/README.md
trackler-2.2.1.174 tracks/csharp/exercises/book-store/README.md
trackler-2.2.1.173 tracks/csharp/exercises/book-store/README.md
trackler-2.2.1.172 tracks/csharp/exercises/book-store/README.md
trackler-2.2.1.171 tracks/csharp/exercises/book-store/README.md
trackler-2.2.1.170 tracks/csharp/exercises/book-store/README.md
trackler-2.2.1.169 tracks/csharp/exercises/book-store/README.md
trackler-2.2.1.167 tracks/csharp/exercises/book-store/README.md
trackler-2.2.1.166 tracks/csharp/exercises/book-store/README.md
trackler-2.2.1.165 tracks/csharp/exercises/book-store/README.md
trackler-2.2.1.164 tracks/csharp/exercises/book-store/README.md
trackler-2.2.1.163 tracks/csharp/exercises/book-store/README.md
trackler-2.2.1.162 tracks/csharp/exercises/book-store/README.md
trackler-2.2.1.161 tracks/csharp/exercises/book-store/README.md
trackler-2.2.1.160 tracks/csharp/exercises/book-store/README.md