RosettaCodeData/Task/Greatest-subsequential-sum/Crystal/greatest-subsequential-sum-2.cr

16 lines
485 B
Crystal
Raw Permalink Normal View History

2023-07-01 11:58:00 -04:00
# the trick is that at any point
# in the iteration if starting a new chain is
# better than your current score with this element
# added to it, then do so.
# the interesting part is proving the math behind it
def subarray_sum(arr)
curr = max = 0
first, last, curr_first = arr.size, 0, 0
arr.each_with_index do |e, i|
curr += e
e > curr && (curr = e; curr_first = i)
curr > max && (max = curr; first = curr_first; last = i)
end
return max, arr[first..last]
end