Submission #1293118

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Source Code Expand

#include <iostream>
using namespace std;
const int mod = 1000000007;
int N, C, A[409], B[409], r[409][409], dp[409][409];
int binpow(int a, int b) {
	int ret = 1;
	while (b) {
		if (b & 1) ret = 1LL * ret * a % mod;
		a = 1LL * a * a % mod;
		b >>= 1;
	}
	return ret;
}
int main() {
	cin >> N >> C;
	for (int i = 0; i < N; i++) cin >> A[i];
	for (int i = 0; i < N; i++) cin >> B[i];
	for (int i = 0; i < N; i++) {
		for (int j = 0; j <= C; j++) {
			for (int k = A[i]; k <= B[i]; k++) {
				r[i][j] += binpow(k, j);
				if (r[i][j] >= mod) r[i][j] -= mod;
			}
		}
	}
	dp[0][0] = 1;
	for (int i = 0; i < N; i++) {
		for (int j = 0; j <= C; j++) {
			for (int k = 0; k <= j; k++) {
				dp[i + 1][j] = (dp[i + 1][j] + 1LL * dp[i][k] * r[i][j - k]) % mod;
			}
		}
	}
	cout << dp[N][C] << endl;
	return 0;
}

Submission Info

Judge Result