#include <bits/stdc++.h>
using namespace std;
#define int long long
#define ll long long
#define pii pair<int, int>
#define ff first
#define ss second
#define pb push_back
#define rep(i, a, b) for (int i = (int)a; i <= (int)b; ++i)
#define rep1(i, a, b) for (int i = (int)a; i >= (int)b; --i)
#define all(x) x.begin(), x.end()
const int N = 2e3 + 5;
const int mod = 1e9 + 7;
int dp[N][N];
signed main() {
int n, a, b; cin >> n >> a >> b;
dp[1][1] = 1;
rep(i, 1, n - 1) rep(j, 1, i) {
if (i + 1 == a || i + 1 == b) {
(dp[i + 1][j] += dp[i][j]) %= mod;
(dp[i + 1][j + 1] += dp[i][j]) %= mod;
}
else {
// merge two components
(dp[i + 1][j - 1] += dp[i][j] * (j - 1)) %= mod;
// create a new component
(dp[i + 1][j + 1] += (dp[i][j] * (j + 1 - (i + 1 > a) - (i + 1 > b)))) %= mod;
}
}
cout << dp[n][1];
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
0 ms |
204 KB |
Output is correct |
2 |
Correct |
0 ms |
204 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
0 ms |
204 KB |
Output is correct |
2 |
Correct |
0 ms |
204 KB |
Output is correct |
3 |
Correct |
0 ms |
332 KB |
Output is correct |
4 |
Correct |
0 ms |
460 KB |
Output is correct |
5 |
Correct |
1 ms |
460 KB |
Output is correct |
6 |
Correct |
1 ms |
460 KB |
Output is correct |
7 |
Correct |
1 ms |
332 KB |
Output is correct |
8 |
Correct |
1 ms |
432 KB |
Output is correct |
9 |
Correct |
1 ms |
460 KB |
Output is correct |
10 |
Correct |
1 ms |
460 KB |
Output is correct |
11 |
Correct |
1 ms |
324 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
0 ms |
204 KB |
Output is correct |
2 |
Correct |
0 ms |
204 KB |
Output is correct |
3 |
Correct |
0 ms |
332 KB |
Output is correct |
4 |
Correct |
0 ms |
460 KB |
Output is correct |
5 |
Correct |
1 ms |
460 KB |
Output is correct |
6 |
Correct |
1 ms |
460 KB |
Output is correct |
7 |
Correct |
1 ms |
332 KB |
Output is correct |
8 |
Correct |
1 ms |
432 KB |
Output is correct |
9 |
Correct |
1 ms |
460 KB |
Output is correct |
10 |
Correct |
1 ms |
460 KB |
Output is correct |
11 |
Correct |
1 ms |
324 KB |
Output is correct |
12 |
Correct |
1 ms |
1228 KB |
Output is correct |
13 |
Correct |
1 ms |
1100 KB |
Output is correct |
14 |
Correct |
1 ms |
1228 KB |
Output is correct |
15 |
Correct |
1 ms |
1228 KB |
Output is correct |
16 |
Correct |
1 ms |
1228 KB |
Output is correct |
17 |
Correct |
2 ms |
1228 KB |
Output is correct |
18 |
Correct |
1 ms |
1100 KB |
Output is correct |
19 |
Correct |
1 ms |
1228 KB |
Output is correct |
20 |
Correct |
1 ms |
1228 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
0 ms |
204 KB |
Output is correct |
2 |
Correct |
0 ms |
204 KB |
Output is correct |
3 |
Correct |
0 ms |
332 KB |
Output is correct |
4 |
Correct |
0 ms |
460 KB |
Output is correct |
5 |
Correct |
1 ms |
460 KB |
Output is correct |
6 |
Correct |
1 ms |
460 KB |
Output is correct |
7 |
Correct |
1 ms |
332 KB |
Output is correct |
8 |
Correct |
1 ms |
432 KB |
Output is correct |
9 |
Correct |
1 ms |
460 KB |
Output is correct |
10 |
Correct |
1 ms |
460 KB |
Output is correct |
11 |
Correct |
1 ms |
324 KB |
Output is correct |
12 |
Correct |
1 ms |
1228 KB |
Output is correct |
13 |
Correct |
1 ms |
1100 KB |
Output is correct |
14 |
Correct |
1 ms |
1228 KB |
Output is correct |
15 |
Correct |
1 ms |
1228 KB |
Output is correct |
16 |
Correct |
1 ms |
1228 KB |
Output is correct |
17 |
Correct |
2 ms |
1228 KB |
Output is correct |
18 |
Correct |
1 ms |
1100 KB |
Output is correct |
19 |
Correct |
1 ms |
1228 KB |
Output is correct |
20 |
Correct |
1 ms |
1228 KB |
Output is correct |
21 |
Correct |
4 ms |
4556 KB |
Output is correct |
22 |
Correct |
4 ms |
5036 KB |
Output is correct |
23 |
Correct |
4 ms |
5452 KB |
Output is correct |
24 |
Correct |
21 ms |
22952 KB |
Output is correct |
25 |
Correct |
20 ms |
22856 KB |
Output is correct |
26 |
Correct |
23 ms |
22980 KB |
Output is correct |
27 |
Correct |
20 ms |
22796 KB |
Output is correct |
28 |
Correct |
14 ms |
15040 KB |
Output is correct |