프로그래머스 | 타겟넘버

function solution(numbers, target) {
    var answer = 0;
    const dfs=(index,sum)=>{
        if(index<numbers.length){
            
        dfs(index+1,sum+numbers[index])
        dfs(index+1,sum-numbers[index])
        }else{
            if(sum===target){
                answer++
            }
        }
    }
    dfs(0,0)
    return answer;
}