+1 Clever Point for checking perfect squre differently than multiplying with the same number.

Very clear and simple solution!

( duplicate comment )

You're performing the Math.sqrt(sq) function twice, it would have been better to put that into a variable. Just to save yourself from calculating it twice. Clean solution though.

temporary issue of CW's servers, not an issue of the kata. Closing.

Thanks, I will check it

java

Help us help you. Tell us in which language you have this problem.

add a "s" behind the "play"

oh shit i missclicked XD
KISS XD

You say in description "returning a list of integer pairs" but you are returning array of arrays in Java.

really bad primes solution

You should provide more details on why adding String in loop is a bad practice (performance issue) and a solution (StringBuilder). I don't remember this kata but a Regex compiled in a loop plus a Scanner are overkill and even worse than a String adding. A better way is to use Pattern/Matcher and parse... function from Double and Integer.

In any case this code is not a 'Best Practices', but a quick-and-dirty simple solution.

you should not add Strings in a loop

it does not generate infite number of primes