#include <bits/stdc++.h>
using namespace std;
#define ll long long
ll mod=1e9+7;
ll mult(ll a, ll b){
return (a*b)%mod;
}
ll chose(ll x){
return ((x*(x-1))/2)%mod;
}
ll dp[3003][3003];
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
ll n,m;
cin >> n >> m;
dp[0][0]=1;
for (ll i = 1; i<=n; i++)dp[i][0]=1;
for (ll i = 1; i<=m; i++)dp[0][i]=1;
for (ll i = 1; i<=n; i++){
for (ll j = 1; j<=m; j++){
dp[i][j]=dp[i-1][j];
dp[i][j]+=mult(4*j,dp[i-1][j-1]);
if (j>=2)dp[i][j]+=mult(chose(j),dp[i-1][j-2]);
if (i>=2 && j>=1)dp[i][j]+=mult(mult(i-1,j),dp[i-2][j-1]);
}
}
cout << (dp[n][m]+mod-1)%mod << '\n';
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
348 KB |
Output is correct |
2 |
Correct |
0 ms |
348 KB |
Output is correct |
3 |
Correct |
1 ms |
604 KB |
Output is correct |
4 |
Correct |
1 ms |
1116 KB |
Output is correct |
5 |
Correct |
1 ms |
604 KB |
Output is correct |
6 |
Correct |
1 ms |
1372 KB |
Output is correct |
7 |
Correct |
1 ms |
860 KB |
Output is correct |
8 |
Correct |
1 ms |
1368 KB |
Output is correct |
9 |
Correct |
1 ms |
860 KB |
Output is correct |
10 |
Correct |
1 ms |
1884 KB |
Output is correct |
11 |
Correct |
0 ms |
348 KB |
Output is correct |
12 |
Correct |
2 ms |
2312 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
348 KB |
Output is correct |
2 |
Correct |
0 ms |
348 KB |
Output is correct |
3 |
Correct |
1 ms |
604 KB |
Output is correct |
4 |
Correct |
1 ms |
1116 KB |
Output is correct |
5 |
Correct |
1 ms |
604 KB |
Output is correct |
6 |
Correct |
1 ms |
1372 KB |
Output is correct |
7 |
Correct |
1 ms |
860 KB |
Output is correct |
8 |
Correct |
1 ms |
1368 KB |
Output is correct |
9 |
Correct |
1 ms |
860 KB |
Output is correct |
10 |
Correct |
1 ms |
1884 KB |
Output is correct |
11 |
Correct |
0 ms |
348 KB |
Output is correct |
12 |
Correct |
2 ms |
2312 KB |
Output is correct |
13 |
Correct |
1 ms |
348 KB |
Output is correct |
14 |
Correct |
4 ms |
9592 KB |
Output is correct |
15 |
Incorrect |
83 ms |
55176 KB |
Output isn't correct |
16 |
Halted |
0 ms |
0 KB |
- |