Submission #86966

#	Time	Username	Problem	Language	Result	Execution time	Memory
86966		Dat160601	Tents (JOI18_tents)	C++17	100 / 100	143 ms	71304 KiB

tents

#include <bits/stdc++.h>
using namespace std;

int n, m;
long long dp[3007][3007];
const long long mod = 1e9 + 7;

int main(){
	ios_base::sync_with_stdio(0);
	cin >> n >> m;
	for(int i = 0; i <= m; i++) dp[0][i] = 1;
	for(int i = 0; i <= n; i++) dp[i][0] = 1;
	for(int i = 1; i <= n; i++){
		for(int j = 1; j <= m; j++){
			dp[i][j] = (dp[i - 1][j] + 4LL * j * dp[i - 1][j - 1]) % mod;
			if(i >= 2) dp[i][j] = (dp[i][j] + 1LL * (i - 1) * j * dp[i - 2][j - 1]) % mod;
			if(j >= 2) dp[i][j] = (dp[i][j] + 1LL * j * (j - 1) / 2LL * dp[i - 1][j - 2]) % mod;
		}
	}
	dp[n][m] = (dp[n][m] - 1 + mod) % mod;
	cout << dp[n][m];
}

• Subtask 1: 48 / 48
• Subtask 2: 52 / 52