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2221. Find Triangular Sum of an Array

MediumOpen on LeetCodeProblem statement

Problem Statement

2221. Find Triangular Sum of an Array

Medium

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.

 

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:

Java — simulation inPlace

Source file
class Solution {
    public int triangularSum(int[] nums) {
        int n = nums.length;
        while (--n >= 1)
            for (int i = 0; i < n; i++)
                nums[i] = (nums[i] + nums[i + 1]) % 10;
        return nums[0];
    }
}