链接
背景
\(Japan\) \(Olympiad\) \(in\) \(Informatics\) \(Spring\) \(Camp\) \(2018\) \(Day1\) \(T3\) ， \(LOJ\) \(2833\)
题意
咕咕咕
解法
细节
代码
$View$ $Code$
//省略头文件
using namespace std;
inline int read()
{
int ret=0,f=1;
char ch=getchar();
while(ch>'9'||ch='0'&&ch<='9')
{
ret=(ret<<1)+(ret<<3)+ch-'0';
ch=getchar();
}
return ret*f;
}
const int mod=1e9+7;
int h,w,ans;
long long dp[3005][3005];
int main()
{
h=read();
w=read();
for(int i=0;i<=h;i++)
{
for(int j=0;j<=w;j++)
{
if(!i||!j)
dp[i][j]=1;
else
{
dp[i][j]=dp[i][j-1]+4*i*dp[i-1][j-1];
if(2<=i)
dp[i][j]+=i*(i-1)/2*dp[i-2][j-1];
if(2<=j)
dp[i][j]+=i*(j-1)*dp[i-1][j-2];
dp[i][j]%=mod;
}
}
}
ans=((dp[h][w]-1)%mod+mod)%mod;
printf("%d\n",ans);
return 0;
}
转载于:https://www.cnblogs.com/Peter0701/p/11361014.html
