Get the sub-array with the maximum sum

max_subarray.rb

def find_max_subarray(array)
  max_sum = current_sum = current_start = start_idx = end_idx = cursor = 0

  while cursor < array.length
    current_test = current_sum + array[cursor]
    if current_test > 0
      if current_sum == 0
        current_start = cursor
      end
      current_sum += array[cursor] 
    else
      current_sum = 0
    end

    if current_sum > max_sum
      max_sum = current_sum 
      start_idx = current_start
      end_idx = cursor
    end
    cursor += 1
  end
  array.slice(start_idx, end_idx - start_idx+1)
end

a = [
  [3,5,1,-9,4],
  [-1,-2,-1,-5,-1],
  [5, 21, -30, 6, 9, 15, 20, -80],
]

a.each do |x|
  p find_max_subarray(x)
end