Find Triangular Sum of an Array

Medium

You receive 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.

Produce the triangular sum of nums.

Example 1

Original illustrative diagram 1 for Find Triangular Sum of an Array

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