타겟넘버

def solution(numbers, target):
    count = 0 #global 
    
    def dfs(i, targetSum):
        nonlocal count 
        #guard closure - count == len(numbers)
        if i == len(numbers):
            if targetSum == target:
                count += 1 
            return 
        dfs(i+1, targetSum + numbers[i])
        dfs(i+1, targetSum - numbers[i]) 
    dfs(0,0)
    return count