Coding Obsession

As part of my Ruby learning process I started the Ruby Koans tutorial, and today I finally completed it. It only took me a couple of hours (spread over a few days) and it was really fun. Koans 177 through 184 were my favorite, they are about a “scoring project” described this way:

Greed is a dice game where you roll up to five dice to accumulate points.  The following "score" function will be used calculate the score of a single roll of the dice. A greed roll is scored as follows:

• A set of three ones is 1000 points
• A set of three numbers (other than ones) is worth 100 times the number. (e.g. three fives is 500 points).
• A one (that is not part of a set of three) is worth 100 points.
• A five (that is not part of a set of three) is worth 50 points.
• Everything else is worth 0 points.

Examples:
score([1,1,1,5,1]) => 1150 points
score([2,3,4,6,2]) => 0 points
score([3,4,5,3,3]) => 350 points
score([1,5,1,2,4]) => 250 points

 

The problem is really simple, but I did my best to solve it in the most “Rubyish” way possible. The final version of my implementation is this:

def  score(dice)
     rank =  Hash. new( 0)
     dice. each {  | x|  rank[x]  +=  1 } 

     finalScore =  (rank[ 1]  /  3)  *  1000
     finalScore +=  100 *  (rank[1]  %  3)
     finalScore +=  50 *  (rank[5]  %  3) 

     rank. delete(1)
     rank. keys. select{|key|  rank[key]  >  2}. each do  |x|
       finalScore +=  x * 100
     end 

     finalScore
 end

Julián Hidalgo Ruby, Ruby Koans Ruby, Ruby Koans