231031 쌍둥이 빌딩 숲

public int solution(int n, int count) {
	if (n == count) {
		return 1;
	}

	long[][] dp = new long[n + 1][count + 1];
	dp[0][0] = 1;

	for (int i = 1; i <= n; i++) {
		for (int j = 1; j <= count; j++) {
			dp[i][j] = calculateDpValue(dp, i, j);
		}
	}

	return (int) dp[n][count];
}

private long calculateDpValue(long[][] dp, int i, int j) {
	return (dp[i - 1][j - 1] + 2L * (i - 1) * dp[i - 1][j]) % 1000000007;
}

출처:https://school.programmers.co.kr/learn/courses/30/lessons/140105