simply cuz 1+1=2
but 97+97!=98

why 20? maybe Math.log(num)+1 ?

findAny() better

findAny() better findFirst()

so slow

bad idea don't do it

your sorting solution has a complexity of O (LogN) when this problem can be solved in O (2N)

see my solution, it passes the tests but does not work correctly with negative values

Not sure why you claim this. The Java reference solution correctly handles this test case. Furthermore, the random tests produce a mix of positive and negative numbers; sometimes they are all negative, and there is no issue with the code.

this O(logN)

its kata can be solved O(N)

Insufficient coverage of tests in the java language. If we take all the numbers negative, then the output does not correspond to the condition of the problem.

sum(new int[]{-1, -50, -100})

assert -50