타겟 넘버

#include <iostream>
#include <string>
#include <vector>

using namespace std;
int answer = 0;
int X(vector<int> numbers,int target,int i){
    for(;i<numbers.size();i++){
        int j = target-(numbers[i]*2);
        if(j == 0)
            answer++;
        if(j>0)
            X(numbers,j,i+1);
    }
    return 0;
}
int solution(vector<int> numbers, int target) {
    int a=0;
    for(int i=0;i<numbers.size();i++){
        a += numbers[i];
    }
    X(numbers,a-target,0);
    return answer;
}