https://programmers.co.kr/learn/courses/30/lessons/43165?language=javascript
function solution(numbers, target) {
let answer = 0;
function getAnswer(x,value) {
if(x<numbers.length){
getAnswer(x+1,value + numbers[x]);
getAnswer(x+1,value - numbers[x]);
} else{
if(value === target){
answer++
}
}
}
getAnswer(0,0);
return answer;
}