#include<bits/stdc++.h>
#define int long long
#define _ ios::sync_with_stdio(0),cout.tie(0),cin.tie(0);
using namespace std;
const int N = 2001, M = 1e9 + 7;
int n, a, b, i, j, dp[N][N];
signed main()
{_
cin >> n >> a >> b; dp[1][1] = 1;
for (i = 2; i <= n; i++)
for (j = 1; j <= i; j++)
if (i == a || i == b) dp[i][j] = (dp[i - 1][j - 1] + dp[i - 1][j]) % M;
else dp[i][j] = (dp[i - 1][j + 1] * j + dp[i - 1][j - 1] * (j - (a < i) - (b < i))) % M;
return cout << dp[n][1], 0;
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
344 KB |
Output is correct |
2 |
Correct |
1 ms |
348 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
344 KB |
Output is correct |
2 |
Correct |
1 ms |
348 KB |
Output is correct |
3 |
Correct |
1 ms |
2396 KB |
Output is correct |
4 |
Correct |
1 ms |
2396 KB |
Output is correct |
5 |
Correct |
1 ms |
2392 KB |
Output is correct |
6 |
Correct |
1 ms |
2516 KB |
Output is correct |
7 |
Correct |
1 ms |
2516 KB |
Output is correct |
8 |
Correct |
1 ms |
2396 KB |
Output is correct |
9 |
Correct |
1 ms |
2392 KB |
Output is correct |
10 |
Correct |
1 ms |
2396 KB |
Output is correct |
11 |
Correct |
1 ms |
2396 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
344 KB |
Output is correct |
2 |
Correct |
1 ms |
348 KB |
Output is correct |
3 |
Correct |
1 ms |
2396 KB |
Output is correct |
4 |
Correct |
1 ms |
2396 KB |
Output is correct |
5 |
Correct |
1 ms |
2392 KB |
Output is correct |
6 |
Correct |
1 ms |
2516 KB |
Output is correct |
7 |
Correct |
1 ms |
2516 KB |
Output is correct |
8 |
Correct |
1 ms |
2396 KB |
Output is correct |
9 |
Correct |
1 ms |
2392 KB |
Output is correct |
10 |
Correct |
1 ms |
2396 KB |
Output is correct |
11 |
Correct |
1 ms |
2396 KB |
Output is correct |
12 |
Correct |
1 ms |
2652 KB |
Output is correct |
13 |
Correct |
1 ms |
2652 KB |
Output is correct |
14 |
Correct |
1 ms |
4444 KB |
Output is correct |
15 |
Correct |
1 ms |
2904 KB |
Output is correct |
16 |
Correct |
2 ms |
4444 KB |
Output is correct |
17 |
Correct |
1 ms |
2772 KB |
Output is correct |
18 |
Correct |
1 ms |
2652 KB |
Output is correct |
19 |
Correct |
1 ms |
2652 KB |
Output is correct |
20 |
Correct |
1 ms |
4440 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
344 KB |
Output is correct |
2 |
Correct |
1 ms |
348 KB |
Output is correct |
3 |
Correct |
1 ms |
2396 KB |
Output is correct |
4 |
Correct |
1 ms |
2396 KB |
Output is correct |
5 |
Correct |
1 ms |
2392 KB |
Output is correct |
6 |
Correct |
1 ms |
2516 KB |
Output is correct |
7 |
Correct |
1 ms |
2516 KB |
Output is correct |
8 |
Correct |
1 ms |
2396 KB |
Output is correct |
9 |
Correct |
1 ms |
2392 KB |
Output is correct |
10 |
Correct |
1 ms |
2396 KB |
Output is correct |
11 |
Correct |
1 ms |
2396 KB |
Output is correct |
12 |
Correct |
1 ms |
2652 KB |
Output is correct |
13 |
Correct |
1 ms |
2652 KB |
Output is correct |
14 |
Correct |
1 ms |
4444 KB |
Output is correct |
15 |
Correct |
1 ms |
2904 KB |
Output is correct |
16 |
Correct |
2 ms |
4444 KB |
Output is correct |
17 |
Correct |
1 ms |
2772 KB |
Output is correct |
18 |
Correct |
1 ms |
2652 KB |
Output is correct |
19 |
Correct |
1 ms |
2652 KB |
Output is correct |
20 |
Correct |
1 ms |
4440 KB |
Output is correct |
21 |
Correct |
3 ms |
7512 KB |
Output is correct |
22 |
Correct |
3 ms |
7772 KB |
Output is correct |
23 |
Correct |
3 ms |
7136 KB |
Output is correct |
24 |
Correct |
21 ms |
24444 KB |
Output is correct |
25 |
Correct |
13 ms |
25688 KB |
Output is correct |
26 |
Correct |
11 ms |
23132 KB |
Output is correct |
27 |
Correct |
12 ms |
22880 KB |
Output is correct |
28 |
Correct |
7 ms |
15196 KB |
Output is correct |