In linear time, find the maximum sum of all possible contiguous subarrays

[DPaul]

Generate random lists of numbers and use the posted code(s) to compute the answer. You don't need an answer sheet when you have code that generates the correct answer.
Personally I think a lot of insight is gained by solving this problem by hand. I blanked on this problem until I wrote a list of numbers and a list of sums. I looked at that for about 10 seconds and the solution was immediately obvious.

Well , I did that of course, but maybe I'm missing something.
What should x = [-1,-2,-3,-4] yield ?
As I understand it : -1
Or are single values not allowed , although it is a "subarray".

Paul