#
# Create by Hua on 7/18/22
#

"""
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 terminates:

Let nums comprise of n elements. If n == 1, end the process. Otherwise, create a new 0-indexed integer array newNums of length n - 1.
For each index i, where 0 <= i < n - 1, assign the value of newNums[i] as (nums[i] + nums[i+1]) % 10, where % denotes modulo operator.
Replace the array nums with newNums.
Repeat the entire process starting from step 1.
Return the triangular sum of nums.



Example 1:


Input: nums = [1,2,3,4,5]
Output: 8
Explanation:
The above diagram depicts the process from which we obtain the triangular sum of the array.
Example 2:

Input: nums = [5]
Output: 5
Explanation:
Since there is only one element in nums, the triangular sum is the value of that element itself.


Constraints:

1 <= nums.length <= 1000
0 <= nums[i] <= 9

"""


class Solution(object):
    def triangularSum(self, nums):
        """
        :type nums: List[int]
        :rtype: int

        thought: simulate array operation.

        07/18/2022 12:02	Accepted	2172 ms	13.5 MB	python
        medium - easy
        5 min. array
        """

        n = len(nums)
        for j in range(n-1, -1, -1):
            for i in range(j):
                nums[i] = (nums[i] + nums[i+1]) % 10
        return nums[0]

