DESCRIPTION:

If we list all the natural numbers below 10 that are multiples of 3 or 5, we get 3, 5, 6 and 9. The sum of these multiples is 23.

Finish the solution so that it returns the sum of all the multiples of 3 or 5 below the number passed in. Additionally, if the number is negative, return 0 (for languages that do have them).

Note: If the number is a multiple of both 3 and 5, only count it once.

Courtesy of projecteuler.net (Problem 1)

// C++
int solution(int number) 
{
  if (number < 3)
    return 0;
  else {
    int sum = 0;
    for (int i = 3; i < number; i++) {
      if (i % 3 == 0 || i % 5 == 0)
        sum += i;
    }
    return sum;
  }
}