2221. Find Triangular Sum of an Array

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:

1. 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.
2. 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.
3. Replace the array nums with newNums.
4. Repeat the entire process starting from step 1.

Return the triangular sum of nums.

class Solution {
public:
    int triangularSum(vector<int>& nums) {
        int n = nums.size();
        for(int ed = n - 1; ed >= 1; ed--) {
            for(int i = 0; i < ed; i++) {
                nums[i] = (nums[i] + nums[i + 1]) % 10;
            }
        }
        
        return nums[0];
    }
};