配列の要素をランキングする

ranking.rb

#!/usr/bin/env ruby

def ranks scores
  ranks = Array.new scores.size, 1
  prev = nil
  rank = 0
  scores.each_with_index do|score, i|
    unless prev == score
      rank = i
    end
    ranks[i] += rank
    prev = scores[i]
  end
  ranks
end

puts ranks([100, 90, 90, 90, 90, 80, 70])

def ranks ary
  rank = ary.sort.reverse
  ary.map{|n| rank.index(n) + 1}
end