Converting find output into a tree of hashes (and a funny use of inject)

tree.rb

tree={}
STDIN.each_line do |l|
  a=l.strip.split '/'
  a.inject(tree) { |t,n| t[n] ||= {} }
end

puts tree.inspect

def rek t, p
  t.each_pair do |k, v|
    if (v.empty?)
      puts p + "/" + k
    else
      rek(v, p + "/" + k)
    end
  end
end

rek tree, ""