static ArrayList<Integer> segregate_evens_and_odds(ArrayList<Integer> numbers) {
        // Write your code here.
        segregate_evens_and_odds_helper(numbers, 0, numbers.size()-1); // pass index only
        System.out.println(numbers);
        return numbers;
    }

    static void segregate_evens_and_odds_helper(ArrayList<Integer> numbers, int start, int end) {
        // Base Case
        if(start >= end) {
            return;
        }

        //Recursive Case
        int odd = start;

        for(int even = start; even <= end-1; even++) {
            if(isEven(numbers.get(even))) {
                Collections.swap(numbers, odd, even) ;
                odd ++;
            }
        }
        Collections.swap(numbers, odd, end);
    }

    static boolean isEven(int number) {
        if(number%2 == 0)
            return true;
        return false;
    }