I encountered the same problem (with the some answer in Ruby), and hadn't a clue how to fix (circumvent) the problem in the test cases - because it is clear that the problem is there. While debugging, I put a p string as the first line in the method... and got the solution accepted. You might want to try that.

Do you have the problem with other Ruby versions as well?

I encountered the same problem (with the very obvious expression in Ruby as my answer), and hadn't a clue how to fix (circumvent) the problem in the test cases. While debugging, I put a p string as the first line in the method... and got the solution accepted. You might want to try that.

Perhaps (now that I think of it) it has something to do with the Ruby version we're using?

I encountered the same problem (with the very obvious answer in Ruby), and hadn't a clue how to fix (circumvent) the problem in the test cases. While debugging, I put a p string as the first line in the method... and got the solution accepted. You might want to try that.

See https://en.wikipedia.org/wiki/Fibonacci_number#Negafibonacci for an explanation of Fibonacci numbers for negative numbers.

And make sure that you compute the power correctly: put parenthesis around the -1, like in (-1) ** ((n.abs)+1) * fib(n.abs) if n < 0

See https://en.wikipedia.org/wiki/Fibonacci_number#Negafibonacci for a description of negative Fibonacci numbers.

BTW, I struggled with this as well, but discovered that (in Ruby) you should put parenthesis around the -1 to have the -1**n work correctly, thus return (-1) ** ((n.abs)+1) * fib(n.abs) if n < 0