nice!

nice hack using length of source as maxlength

Also,

strings.Split(s, " ") is equvalent to string.Fields(s)

I'd say the proper way is:

import "unicode/utf8"

utf8.RuneCountInString()

Seen this on Go blog.
Cheers :)

This solutions doesn't account for unicode characters!
E.g. len("→") => 2
Use len([]rune("→") => 1

I got this output (and failed the final tests) in exactly the same way because I was trying to use string() to cast a rune. In order to pass the randomized test, the code needs to be able to account for runes greater than a single byte.

I actually only had to make minimal changes to my code to pass the tests otherwise, so I'm leaving this for anyone else who may be tripped up by this - hopefully not spoiling too much :)