def min_distance(from_word, to_word)
  count = 0
  words = [from_word]
  loop {
    return count if (words.include?(to_word))
    new_words = Array.new
    words.each { |word|
      index = 0
      rindex = -1
      index += 1 until (word[index] != to_word[index])
      rindex -= 1 until (word[rindex] != to_word[rindex])
      if (word.length >= to_word.length)
        new_word = word.clone
        rnew_word = word.clone
        new_word.slice!(index)
        rnew_word.slice!(rindex)
      end
      if (word.length <= to_word.length)
        new_word = word.clone
        rnew_word = word.clone
        new_word.insert(index, to_word[index])
        rnew_word.insert(rindex, to_word[rindex])
      end
      new_words.push(new_word, rnew_word)
      if (index < [word.length, to_word.length].min)
        new_word = word.clone
        new_word[index] = to_word[index]
        new_words.push(new_word)
      end
      if (rindex.abs < [word.length, to_word.length].min)
        new_word = word.clone
        new_word[rindex] = to_word[rindex]
        new_words.push(new_word)
      end
    }
    count += 1
    words = new_words
  }
end