radix lsd sort in ruby http://en.wikipedia.org/wiki/Radix_sort#Least_significant_digit_radix_sorts

radix_lsd.rb

def lrgst(a)
  largest = 0
  a.each {|i| largest = i if i > largest }
  largest
end

def radix_lsd(uns)
  sorted = (0..Math.log10(lrgst(uns)).floor).inject(uns) do |memo, index|
    groups = Array.new(10).map{|x| [] }
    memo.each { |u| groups[(u / 10**index) % 10] << u }
    groups.flatten
  end
end