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#2221 - Find Triangular Sum of an Array

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Array Math Simulation Combinatorics

Problem Description

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.

Solution

/**
 * @param {number[]} nums
 * @return {number}
 */
var triangularSum = function(nums) {
  while (nums.length > 1) {
    const updated = [];
    for (let i = 0; i < nums.length - 1; i++) {
      updated.push((nums[i] + nums[i + 1]) % 10);
    }
    nums = updated;
  }
  return nums[0];
};