From: "Benjamin J. Tilly" <ben_tilly@...>
Date: 2001-03-10T15:21:58+09:00
Subject: [ruby-talk:12375] Re: ...and the challenge

This version is the fastest on my machine.  YMMV.

Where it differs from my previous one is that I avoid redoing
the multiplications by the generators.  I tried a few other
designs out, but this seemed best.

Incidentally it is mildly irritating, but the to_i method does
not strip out _.  So this will not do what you want if you do:

ruby hamming.rby 1_000_000

You need to make that

ruby hamming.rby 1000000

Cheers,
Ben

   class HammingSeq
      attr_reader :generators
      attr :pos
      attr :seq
      attr :vals

      def initialize (*generators)
        if 0 == generators.length
          raise "Cannot create a sequence without generators"
        end
        @generators = generators
        @pos = Array.new (generators.length, 0)
        @vals = generators.dup
        # Need elements 0 and 1 to avoid infinite recursion
        @seq = [1, @generators.min]
        # We have the first elem manually inserted, so throw one away.
        next_elem
      end

      def [] (n)
        while @seq.length <= n
          @seq.push next_elem
        end
        @seq[n]
      end

      def next_elem
        min_val = @vals.min
        @vals.each_index {|i|
          if min_val == vals[i]
            @pos[i] += 1
            @vals[i] = @generators[i] * @seq[@pos[i]]
          end
        }
        min_val
      end
    end

    hamming = HammingSeq.new(2, 3, 5)
    max = ARGV[0].to_i
    for i in 0..max do
      val = hamming[i]
      if val <= max
        puts val
      else
        break
      end
    end
    puts "Done"

-------------------------------------------
The Fastest Browser on Earth now for FREE!!
Download Opera 5 for Windows now! Get it at
http://www.opera.com/download/
-------------------------------------------