BOJ - 5557 - 1학년

import sys

def solution():
    N = int(input())
    arr = list(map(int, sys.stdin.readline().split()))
    dp = [[0 for _ in range(21)] for _ in range(N-1)]

    dp[0][arr[0]] += 1

    for i in range(len(arr)-1):
        for j in range(21):
            data = dp[i-1][j]
            if data:
                if j - arr[i] > -1:
                    dp[i][j - arr[i]] += data
                if j + arr[i] < 21:
                    dp[i][j + arr[i]] += data

    print(dp[-1][arr[-1]])

solution()

https://www.acmicpc.net/problem/5557