Largest Contiguous Sum of Array with positive and negative integers

largest_array_sum.py

def largest_array_sum(arr):
    n = len(arr)
    if n < 1:
        return 0
    if n < 2:
        return arr[0]
    max_sum = float("-inf")
    current_sum = arr[0]
    for num in arr[1:]:
        current_sum = max(current_sum + num, num)
        max_sum = max(max_sum, current_sum)
    return max_sum

print(largest_array_sum([7, 1, 2, -1, 3, 4, 10, -12, 3, 21, -19]))