@Kasia1946 Hi,Kasia... Well , What's the Language You Tried to solve the problem in ?? .. I'm tuned to know .. Regards ...Zizou

Hi, when its testing the code 2nd time, all the arrays return as expected: 0, why?

Are you sure you are not modifying the original array?

I think there is a problem with the random tests in Ruby. They all expect "0" when it is clearly not.

Thanks, I'd forgotten that mutating the string in place can lead to failed tests.

Or maybe you are mutating the string in place?

I think the random tests in Ruby are expecting the input not the output.