recursive huffman coding

huffmancode.rb

def buildHuffmanCode(ftab)
    if ftab.length == 1
        ftab
    else
        ftab = ftab.sort {|a,b| a[0] <=> b[0]}
        left = ftab[0]
        right = ftab[1]
        freq = left[0]+right[0]
        left = left[1].map{|x| x.merge({:code => "0"+x[:code]})}
        right = right[1].map{|x| x.merge({:code => "1"+x[:code]})}
        buildHuffmanCode(ftab[2..-1]+[[freq,left+right]])
    end
end

def hashToFrequencyTable(ft)
    ft.map{|sym,freq|
        [freq,[{:sym => sym, :code => ""}]]
    }
end

ft = {"a" => 45, "b" => 13, "c" => 12, "d" => 16, "e" => 9, "f" => 5}
buildHuffmanCode(hashToFrequencyTable(ft))[0][1].each{|x|
    puts "#{x[:sym]} => #{x[:code]}"
}