ruby - Ruby: 文字列再構築アルゴリズム、部分的にしか機能しない

Question

Ruby で文字列再構築アルゴリズム (動的プログラミングの例では古典的で、スペースのないテキストを通常のスペースのテキストに変換する) に取り組んでいます。以下のコードは純粋な Ruby です。コピーして貼り付けてすぐにテストを開始できます。80% の確率で動作し、辞書が大きくなるほど壊れる傾向があります。私は 80,000 語以上の辞書でテストしましたが、約 70% の確率でうまく機能しません。

単語が辞書に存在する場合に 100% 機能させる方法があれば、教えてください。

コードは次のとおりです（十分な間隔があり、非常に読みやすいはずです）

# Partially working string reconstruction algo in pure Ruby

# the dictionary
def dict(someWord)
  myArray = [" ", "best", "domain", "my", "successes", "image", "resizer", "high", "tech", "crime", "unit", "name", "edge", "times", "find", "a", "bargain", "free", "spirited", "style", "i", "command", "go", "direct", "to", "harness", "the", "force"]
  return !!(myArray.index(someWord))
end


# inspired by http://cseweb.ucsd.edu/classes/wi12/cse202-a/lecture6-final.pdf

## Please uncomment the one you wanna use
#
# (all the words used are present in the dictionary above)
#
# working sentences
  x = ' ' + "harnesstheforce"
# x = ' ' + "hightechcrimeunit"
#
# non working sentences
# x = ' ' + "findabargain"
# x = ' ' + "icommand"

puts "Trying to reconstruct #{x}"

# useful variables we're going to use in our algo
n = x.length
k = Array.new(n)
s = Array.new(n)
breakpoints = Hash.new
validBreakpoints = Hash.new

begin

  # let's fill k
  for i in 0..n-1
    k[i] = i
  end

  # the core algo starts here
  s[0] = true
  for k in 1..n-1

    s[k] = false

    for j in 1..k
      if s[j-1] && dict(x[j..k])
        s[k] = true

        # using a hash is just a trick to not have duplicates
        breakpoints.store(k, true)
      end
    end

  end

  # debug
  puts "breakpoints: #{breakpoints.inspect} for #{x}"

  # let's create a valid break point vector

  i=1
  while i <= n-1 do

    # we choose the longest valid word
    breakpoints.keys.sort.each do |k|

      if i >= k
        next
      end

      # debug: when the algo breaks, it does so here and goes into an infinite loop
      #puts "x[#{i}..#{k}]: #{x[i..k]}"
      if dict(x[i..k])
        validBreakpoints[i] = k
      end
    end

    if validBreakpoints[i]
      i = validBreakpoints[i] + 1
    end

  end

  # debug
  puts "validBreakpoints: #{validBreakpoints.inspect} for #{x}"

  # we insert the spaces at the places defined by the valid breakpoints
  x = x.strip
  i = 0
  validBreakpoints.each_key do |key|
    validBreakpoints[key] = validBreakpoints[key] + i
    i += 1
  end

  validBreakpoints.each_value do |value|
    x.insert(value, ' ')
  end

  puts "Debug: x: #{x}"


  # we capture ctrl-c
rescue SignalException
  abort

# end of rescue
end