# 2221. Find Triangular Sum of an Array from math import comb """ you are given a 0-indexed integer array 'nums', where 'nums[i]' is a digit between 0 and 9 inclusive. the triangular sum of 'nums' is the value of the only element present in 'nums' after the following process concludes: let 'nums' comprise of 'n' elements. if 'n == 1', end the process. otherwise, create a new 0-indexed integer array 'new_nums' of length 'n - 1'. for each index 'i' where '0 <= i < n - 1', assign the value of 'new_nums[i]' as '(nums[i] + nums[i + 1]) % 10'. replace the array 'nums' with 'new_nums', and repeat the entire process starting again. """ class Solution(object): def triangularSum(self, nums): """ :type nums: List[int] :rtype: int """ return sum(n * comb(len(nums) - 1, i) for i, n in enumerate(nums)) % 10 if __name__ == "__main__": obj = Solution() print(obj.triangularSum(nums=[1, 2, 3, 4, 5])) print(obj.triangularSum(nums=[5]))