[C++] 프로그래머스 타겟 넘버

#include <string>
#include <vector>

using namespace std;

int answer = 0;

void Find(const vector<int>& numbers, int target, int sum, int index) {
    if (index == numbers.size()) {
        if (sum == target) answer++;
        return;
    }

    Find(numbers, target, sum + numbers[index], index + 1);
    Find(numbers, target, sum - numbers[index], index + 1);
}

int solution(vector<int> numbers, int target) {
    answer = 0;
    Find(numbers, target, 0, 0); 
    return answer;
}