Submission #386285

#	Time	Username	Problem	Language	Result	Execution time	Memory
386285		ogibogi2004	Tents (JOI18_tents)	C++14	100 / 100	485 ms	71148 KiB

tents

#include<bits/stdc++.h>
using namespace std;
#define ll long long
const ll mod=1e9+7;
ll dp[3002][3002];
ll n,m;
ll solve(ll x,ll y)
{
	if(x==0||y==0)return 1;
	if(x<0||y<0)return 0;
	if(dp[x][y]!=-1)return dp[x][y];
	ll val=0;
	val+=solve(x,y-1);
	val+=x*4*solve(x-1,y-1);
	val%=mod;
	val+=x*(x-1)/2*solve(x-2,y-1);
	val%=mod;
	val+=x*(y-1)*solve(x-1,y-2);
	val%=mod;
	return dp[x][y]=val;
}
int main()
{
	memset(dp,-1,sizeof(dp));
	cin>>n>>m;
	cout<<(solve(n,m)+mod-1)%mod<<endl;
return 0;
}

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