Brainf*ck

bf.rb

# coding: utf-8
# bf.rb
# 入力された文字列を出力する Brainf*ck コードを出力する

def f(num)
  if num <= 13 then
    return false
  end
  lst = []
  cnt = 0
  2.upto(Math.sqrt(num).to_i) do |i|
    if num % i == 0 then
      lst[cnt] = [i, num / i]
      cnt += 1
    end
  end
  if lst.empty? then
    return false
  end
  lst.sort!{|a,b|a[0]+a[1]<=>b[0]+b[1]}
  return lst[0]
end

if not ARGV[0] then
  print " > "
  input = gets.chomp.bytes.to_a
else
  input = ARGV[0].bytes.to_a
end

input.size.times do |a|
  if a == 0 then
    lst = f(input[a])
    if not lst then
      if input[0] <= 13 then
        print ">", "+"*input[0]
      else
        1.upto(input[0]) do |count|
          lste = f(input[0]-count)
          if lste then
            print "+"*lste[0], "[>", "+"*lste[1], "<-]>", "+"*count
            break
          else
            lste = f(input[0]+count)
            if lste then
              print "+"*lste[0], "[>", "+"*lste[1], "<-]>", "-"*count
              break
            end
          end
        end
      end
    else
      print "+"*lst[0], "[>", "+"*lst[1], "<-]>"
    end
  else
    delta = input[a] - input[a-1]
    delta_abs = delta.abs
    lst = f(delta_abs)
    if delta < 0 then
      if not lst then
        if delta_abs <= 13 then
          print "-"*delta_abs
        else
          1.upto(delta_abs) do |count|
            lste = f(delta_abs-count)
            if lste then
              print "<", "+"*lste[0], "[>", "-"*lste[1], "<-]>", "-"*count
              break
            else
              lste = f(delta_abs+count)
              if lste then
                print "<", "+"*lste[0], "[>", "-"*lste[1], "<-]>", "+"*count
                break
              end
            end
          end
        end
      else
        print "<", "+"*lst[0], "[>", "-"*lst[1], "<-]>"
      end
    elsif delta > 0 then
      if not lst then
        if delta_abs <= 13 then
          print "+"*delta_abs
        else
          1.upto(delta_abs) do |count|
            lste = f(delta_abs-count)
            if lste then
              print "<", "+"*lste[0], "[>", "+"*lste[1], "<-]>", "+"*count
              break
            else
              lste = f(delta_abs+count)
              if lste then
                print "<", "+"*lste[0], "[>", "+"*lste[1], "<-]>", "-"*count
                break
              end
            end
          end
        end
      else
        print "<", "+"*lst[0], "[>", "+"*lst[1], "<-]>"
      end
    end
  end
  print "."
end