#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int maxn = 3000 + 10;
const int mod = 1e9 + 7;
int dp[maxn][maxn];
int power(int a, int b){
if (b == 0)
return 1;
int ret = power(a, b / 2);
ret = 1ll * ret * ret % mod;
if (b & 1)
return 1ll * ret * a % mod;
return ret;
}
int main(){
ios_base::sync_with_stdio(false);
int n, m;
cin >> n >> m;
for (int i = 0; i <= max(n, m); i++)
dp[i][0] = dp[0][i] = 1;
for (int i = 1; i <= n; i++){
for (int j = 1; j <= m; j++){
if (i == 1){
dp[i][j] = 4 * j + 1ll * j * (j - 1) % mod * power(2, mod - 2) % mod + 1;
dp[i][j] %= mod;
continue;
}
if (j == 1){
dp[i][j] = 4 * i + 1ll * i * (i - 1) % mod * power(2, mod - 2) % mod + 1;
dp[i][j] %= mod;
continue;
}
dp[i][j] = dp[i - 1][j];
dp[i][j] = (dp[i][j] + 4ll * dp[i - 1][j - 1] * j) % mod;
dp[i][j] = (dp[i][j] + 1ll * dp[i - 1][j - 2] * j % mod * (j - 1) % mod * power(2, mod - 2) % mod) % mod;
dp[i][j] = (dp[i][j] + 1ll * dp[i - 2][j - 1] * j % mod * (i - 1) % mod) % mod;
}
}
cout << (dp[n][m] - 1 + mod) % mod << endl;
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
2 ms |
384 KB |
Output is correct |
2 |
Correct |
3 ms |
1024 KB |
Output is correct |
3 |
Correct |
2 ms |
512 KB |
Output is correct |
4 |
Correct |
3 ms |
1152 KB |
Output is correct |
5 |
Correct |
8 ms |
1408 KB |
Output is correct |
6 |
Correct |
9 ms |
1408 KB |
Output is correct |
7 |
Correct |
9 ms |
1152 KB |
Output is correct |
8 |
Correct |
8 ms |
1408 KB |
Output is correct |
9 |
Correct |
3 ms |
896 KB |
Output is correct |
10 |
Correct |
16 ms |
1664 KB |
Output is correct |
11 |
Correct |
4 ms |
1508 KB |
Output is correct |
12 |
Correct |
32 ms |
2056 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
2 ms |
384 KB |
Output is correct |
2 |
Correct |
3 ms |
1024 KB |
Output is correct |
3 |
Correct |
2 ms |
512 KB |
Output is correct |
4 |
Correct |
3 ms |
1152 KB |
Output is correct |
5 |
Correct |
8 ms |
1408 KB |
Output is correct |
6 |
Correct |
9 ms |
1408 KB |
Output is correct |
7 |
Correct |
9 ms |
1152 KB |
Output is correct |
8 |
Correct |
8 ms |
1408 KB |
Output is correct |
9 |
Correct |
3 ms |
896 KB |
Output is correct |
10 |
Correct |
16 ms |
1664 KB |
Output is correct |
11 |
Correct |
4 ms |
1508 KB |
Output is correct |
12 |
Correct |
32 ms |
2056 KB |
Output is correct |
13 |
Correct |
10 ms |
7808 KB |
Output is correct |
14 |
Correct |
11 ms |
9600 KB |
Output is correct |
15 |
Correct |
1762 ms |
32864 KB |
Output is correct |
16 |
Correct |
121 ms |
8108 KB |
Output is correct |
17 |
Correct |
388 ms |
12536 KB |
Output is correct |
18 |
Correct |
481 ms |
11796 KB |
Output is correct |
19 |
Execution timed out |
2029 ms |
34440 KB |
Time limit exceeded |
20 |
Halted |
0 ms |
0 KB |
- |