#2894 - Divisible and Non-divisible Sums Difference

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Problem Description

You are given positive integers n and m.

Define two integers as follows:

num1: The sum of all integers in the range [1, n] (both inclusive) that are not divisible by m.
num2: The sum of all integers in the range [1, n] (both inclusive) that are divisible by m.

Return the integer num1 - num2.

Solution

/**
 * @param {number} n
 * @param {number} m
 * @return {number}
 */
var differenceOfSums = function(n, m) {
  let nonDivisibleSum = 0;
  let divisibleSum = 0;

  for (let i = 1; i <= n; i++) {
    if (i % m === 0) {
      divisibleSum += i;
    } else {
      nonDivisibleSum += i;
    }
  }

  return nonDivisibleSum - divisibleSum;
};