# A legen – eight for it – dary Twitter contest courtesy of Neil Patrick Harris

On March 2 at 7:25 EST, Neil Patrick Harris tweeted to his 8 million Twitter followers:

A mere three minutes following the puzzle, NPH tweeted:

So how did Tommy MacWilliam solve the puzzle in less than one minute?

On Quora, someone posed the question “Neil Patrick Harris: How did Tommy MacWilliam solve Neil Patrick Harris’s Twitter puzzle?” MacWilliam – who describes himself on Quora as a “Classic Schmosby” answered:

Amazing timing. I happened to be browsing Twitter the moment Neil Patrick Harris tweeted: “Puzzle time: solve my next tweet before anyone else and win something awesome from me.” (https://twitter.com/ActuallyNPH/…), so I figured I’d give it a try.

I took a shot in the dark that the text was encrypted using the Caesar cipher, since it’s one of the more straightforward ways to encrypt a message. The Caesar cipher works by shifting each letter in the alphabet by the same number of places; for example, if we were rotating all letters by 13 places (which is called ROT-13), then “A” would become “N”, “B” would become “O”, and so on, like this:

Unfortunately, trying to rotate every character by 13 places didn’t give me anything readable, so I proceeded to try every possible rotation value (also called a “key”) until I got something readable. Turns out that a key of 19 gives the message: “First person to tweet back ‘Legen – eight for it – dary’ wins!”* I was pretty shocked that my method actually worked, so I immediately tweeted back at NPH. I was even more shocked to find out that I was the first person to solve the puzzle. I’m not sure what I won yet, but I’ll update this thread as soon as I find out!

As for how I solved it so quickly, probably just my excitement, since I’m a hugeHow I Met Your Mother fan 🙂

* NPH just reached eight million Twitter followers, and the phrase “Legen – wait for it – dary” is one of his catchphrases from the show.