Performance Computing: Perl Advisor: Figuring Phone-y Words

“Every day, we seem barraged with phone numbers that “spell”
things, like “please dial 1-ZZZ-HE-MUST-PAY to force your older
brother to pay for the call!” That’s because since nearly day one
of dial phone service (back when it was really a dial), we’ve had
these letters that go along with each of the digits.”

“On one of the many mailing lists I follow, a question came
up the other day: someone wanted to know if there were any large
sets of words that all collided to the same number. I thought
that’d be a perfect job for Perl, and in a short time, came up with
a quick program to scan through the standard UNIXdictionary in
/usr/dict/words to find the longest such collision list (or lists,
if more than one). Since the program illustrates some basic data
reduction techniques, I thought I’d pass it along to you as
well.”

“First, comes the most critical part. Given an arbitrary string,
like “merlyn,” what are the digits used to construct that? Well, we
need to know that m is 6, and e is 3, and so on. Now, there are
many slow ways to do this, but the fastest way is a tr
operator…”

Complete
Story