백준 2225 합분해

n, k = map(int, input().split())
mod = 1000000000
check = [[0] * (n+1) for _ in range(k+1)]
check[0][0] = 1
for i in range(1, k+1):
    for j in range(n+1):
        for l in range(j+1):
            check[i][j] += check[i-1][j-l]
        check[i][j] %= mod
print(check[k][n])

dp + 이차원배열