If brute force finds an answer, it's just as good for me. =P
Remember:
"Hmm." Kenichi Nakamura frowned. He was a middle-aged programmer. Though one of the club's best codebreakers, the code-on-a-string had briefly confused him, as no numbers were involved in its solution.
And also:
"You could find those on the Internet!" Mr. Nakamura was not happy with this development, and he could see that Ocean Zweidler seemed equally fed-up. "The real answer to the string took research, too, even if it was easier for you! But if all of these riddles are about your mother, we suffer a disadvantage."
EDIT: Bold emphasis is mine.