class Solution {
public int solution(int[] numbers, int target) {
int answer = dfs(0, 0, target, numbers);
return answer;
}
public int dfs(int idx, int sum, int target, int[] numbers) {
if (idx >= numbers.length) {
if (sum == target) return 1;
else return 0;
}
return dfs(idx + 1, sum + numbers[idx], target, numbers)
+ dfs(idx + 1, sum - numbers[idx], target, numbers);
}
}