This is a work of art. Beautiful.

I know absolutely nothing about nodes, yet I don't understand why this is 3 kyu. Nothing special, at least in Java.

I don't understand why this is 4 kyu. Are the test cases so simplistic that I am actually doing something I shouldn't?

I misunderstood both the problem and the approach that should be used.

I admit I was wrong, although I find strange the amount of people, including myself, who think the problem had to be solved with square root. I was also reading the expected value wrong in test 3.

However it's kind of almost everywhere in the description where you talk about squaring...

You can multiply a negative value with itself and it will give the same result as if you multiplied with positive values, but if you square root the result it's mathematically impossible to get a negative result.

So yeah, you can make it pass if instead of square rooting the "b" list you square the "a" list instead, which is incorrect if the focus of the problem is square root and not the opposite.

On Java tests, test 3 expects true when array "a" is empty and on test 8 the second value on array "a" is a negative and expects true, you can't get negative values from square root.