maximum_subsequence.py

from collections.abc import Sequence


def max_subsequence_sum(nums: Sequence[int] | None = None) -> int:
 """Return the maximum possible sum amongst all non - empty subsequences.

 Raises:
 ValueError: when nums is empty.

 >>> max_subsequence_sum([1,2,3,4,-2])
 10
 >>> max_subsequence_sum([-2, -3, -1, -4, -6])
 -1
 >>> max_subsequence_sum([])
 Traceback (most recent call last):
 . . .
 ValueError: Input sequence should not be empty
 >>> max_subsequence_sum()
 Traceback (most recent call last):
 . . .
 ValueError: Input sequence should not be empty
 """
 if nums is None or not nums:
 raise ValueError("Input sequence should not be empty")

 ans = nums[0]
 for i in range(1, len(nums)):
 num = nums[i]
 ans = max(ans, ans + num, num)

 return ans


if __name__ == "__main__":
 import doctest

 doctest.testmod()

 # Try on a sample input from the user
 n = int(input("Enter number of elements : ").strip())
 array = list(map(int, input("\nEnter the numbers : ").strip().split()))[:n]
 print(max_subsequence_sum(array))