class Solution {
    private static int answer;

    public static int solution(int[] numbers, int target) {
        answer = 0;
        calcNumber(numbers, target, 0, 0);
        return answer;
    }

    private static void calcNumber(int[] numbers, int target, int total, int idx) {
        if (idx >= numbers.length) {
            if (total == target) {
                answer++;
            }
            return;
        }

        int num = numbers[idx];
        calcNumber(numbers, target, total + num, idx + 1);
        calcNumber(numbers, target, total - num, idx + 1);
    }
}