Submission #94112

#	Time	Username	Problem	Language	Result	Execution time	Memory
94112		autumn_eel	Tents (JOI18_tents)	C++14	100 / 100	139 ms	82248 KiB

tents

#include <bits/stdc++.h>
#define rep(i,n)for(int i=0;i<(n);i++)
#define MOD 1000000007
using namespace std;
typedef long long ll;

ll dp[4000][4000];
int main(){
	int h,w;cin>>h>>w;
	dp[0][w]=1;
	rep(i,h)rep(j,w+1){
		//0
		(dp[i+1][j]+=dp[i][j])%=MOD;
		//1
		if(j)(dp[i+1][j-1]+=dp[i][j]*j*4)%=MOD;
		//N-S
		if(j&&i<h-1)(dp[i+2][j-1]+=dp[i][j]*j*(h-i-1))%=MOD;
		//E-W
		if(j>=2)(dp[i+1][j-2]+=dp[i][j]*(j*(j-1)/2))%=MOD;
	}
	ll ans=0;
	rep(i,w+1)(ans+=dp[h][i])%=MOD;
	cout<<(ans+MOD-1)%MOD<<endl;
}

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