#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N = 3e3+10;
const int MOD = 1e9+7;
ll dp[N][N], n, m;
// From (N, M) we can:
// 1) do nothing and go to (N-1, M)
// 2) put random tent in N-th row in any direction 4*M * (N-1, M-1)
// 3) put 2 tents in N-th row in M*(M-1)/2 * (N-1, M-2)
// 4) put 2 tents in same column s.t. on is in N-th row in M*(N-1)*(N-2, M-1) ways
ll solve(ll n, ll m) {
if (n <= 0 || m <= 0) return 1;
if (dp[n][m] > 0) return dp[n][m];
ll res=solve(n-1, m);
(res+=4*m*solve(n-1, m-1))%=MOD;
(res+=m*(m-1)/2*solve(n-1, m-2))%=MOD;
(res+=m*(n-1)*solve(n-2, m-1))%=MOD;
return dp[n][m]=res;
}
int main() {
cin>>n>>m;
cout<<solve(n, m)-1<<"\n";
}
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
0 ms |
212 KB |
Output is correct |
| 2 |
Correct |
0 ms |
212 KB |
Output is correct |
| 3 |
Correct |
0 ms |
468 KB |
Output is correct |
| 4 |
Correct |
1 ms |
1108 KB |
Output is correct |
| 5 |
Correct |
1 ms |
596 KB |
Output is correct |
| 6 |
Correct |
1 ms |
1364 KB |
Output is correct |
| 7 |
Correct |
1 ms |
724 KB |
Output is correct |
| 8 |
Correct |
1 ms |
1364 KB |
Output is correct |
| 9 |
Correct |
1 ms |
724 KB |
Output is correct |
| 10 |
Correct |
2 ms |
1748 KB |
Output is correct |
| 11 |
Correct |
1 ms |
312 KB |
Output is correct |
| 12 |
Correct |
3 ms |
2004 KB |
Output is correct |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
0 ms |
212 KB |
Output is correct |
| 2 |
Correct |
0 ms |
212 KB |
Output is correct |
| 3 |
Correct |
0 ms |
468 KB |
Output is correct |
| 4 |
Correct |
1 ms |
1108 KB |
Output is correct |
| 5 |
Correct |
1 ms |
596 KB |
Output is correct |
| 6 |
Correct |
1 ms |
1364 KB |
Output is correct |
| 7 |
Correct |
1 ms |
724 KB |
Output is correct |
| 8 |
Correct |
1 ms |
1364 KB |
Output is correct |
| 9 |
Correct |
1 ms |
724 KB |
Output is correct |
| 10 |
Correct |
2 ms |
1748 KB |
Output is correct |
| 11 |
Correct |
1 ms |
312 KB |
Output is correct |
| 12 |
Correct |
3 ms |
2004 KB |
Output is correct |
| 13 |
Correct |
0 ms |
212 KB |
Output is correct |
| 14 |
Correct |
5 ms |
9812 KB |
Output is correct |
| 15 |
Correct |
133 ms |
47368 KB |
Output is correct |
| 16 |
Correct |
2 ms |
1620 KB |
Output is correct |
| 17 |
Correct |
13 ms |
6816 KB |
Output is correct |
| 18 |
Correct |
35 ms |
13572 KB |
Output is correct |
| 19 |
Correct |
148 ms |
53324 KB |
Output is correct |
| 20 |
Correct |
114 ms |
42196 KB |
Output is correct |
| 21 |
Correct |
66 ms |
25496 KB |
Output is correct |
| 22 |
Correct |
74 ms |
30812 KB |
Output is correct |
| 23 |
Correct |
51 ms |
26444 KB |
Output is correct |
| 24 |
Correct |
189 ms |
58972 KB |
Output is correct |
| 25 |
Correct |
136 ms |
49376 KB |
Output is correct |
| 26 |
Correct |
158 ms |
54696 KB |
Output is correct |
| 27 |
Correct |
192 ms |
57176 KB |
Output is correct |
