프로그래머스/DFS,BFS/타겟 넘버

https://programmers.co.kr/learn/courses/30/lessons/43165

level1

def solution(numbers, target):
    answer = 0
    def dfs(idx=0):
        if idx < len(numbers):
            numbers[idx] *= 1
            dfs(idx+1)
            numbers[idx] *= -1
            dfs(idx+1)
            
        elif sum(numbers) == target:
            nonlocal answer
            answer += 1
    dfs() 
    return answer