Solution for Project Euler #1

projecteuler1.java

public static void problem1(){
        Set<Integer> multiples = new HashSet<Integer>();

        for(int i=1; i<1000; i++){
            if(i%3==0 || i%5==0){
                multiples.add(i);
            }
        }
        
        Integer[] numbers = multiples.toArray(new Integer[multiples.size()]);
        
        int total = 0;
        for(int i=0; i<numbers.length; i++){
            total += numbers[i];
        }
        System.out.println(total);
    }