Split data and Cross tabulation

#!/usr/bin/ruby
# coding: utf-8
ret = Hash.new {|hash, k| hash[k] = 0 }
DATA.each_line do |line|
  keys = line.split(':')
  val = keys.pop.to_i
  keys.each {|k| ret[k] += val }
end
ret.each {|k, v| puts "#{k}: #{v}" }
__END__
a:b:c:10
a:e:20
b:e:30