#2342 - Max Sum of a Pair With Equal Sum of Digits

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Problem Description

You are given a 0-indexed array nums consisting of positive integers. You can choose two indices i and j, such that i != j, and the sum of digits of the number nums[i] is equal to that of nums[j].

Return the maximum value of nums[i] + nums[j] that you can obtain over all possible indices i and j that satisfy the conditions.

Solution

/**
 * @param {number[]} nums
 * @return {number}
 */
var maximumSum = function(nums) {
  const map = new Map();

  return nums.reduce((result, n) => {
    const key = n.toString().split('').reduce((sum, n) => +n + sum, 0);
    result = !map.has(key) ? result : Math.max(result, n + map.get(key));
    map.set(key, Math.max(map.get(key) ?? 0, n));

    return result;
  }, -1);
};