This solution is not correct.

try this. actual answer should be 6.

console.log(maxSequence([-2, 1, -3, 4, -1, 2, 1, -5, 4]));

Still a pure function because in order for it to be impure , it would have to access variables OUTSIDE of the function call...this function would always output the exact same thing if given the same input because there is no outside state effecting what happens inside the function...

пиздец, я в шоке, как таким умным можно быть-то блять.

Your reducer is not a pure function because references currentSum which life outsize the function.

why not?