#ifdef LOCAL
#include <prettyprint.hpp>
#endif
#include<bits/stdc++.h>
#define endl '\n'
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define lg2(x) __lg(x)
#define rem_dupl(x) sort(all(x)); x.erase(unique(all(x)), x.end())
using namespace std;
typedef long long ll;
typedef double db;
typedef pair<int,int> ii;
#define x first
#define y second
//mt19937 rand32(chrono::steady_clock::now().time_since_epoch().count());
//mt19937_64 rand64(chrono::steady_clock::now().time_since_epoch().count());
const db eps = 1e-9;
const int maxn = (int)2e3 + 5;
const ll mod = (int)1e9 + 7; // 998244353
ll mul(ll a, ll b){
return a * b % mod;
}
ll add(ll a, ll b){
return (a + b)%mod;
}
ll dp[maxn][maxn];
int main() {
ios_base::sync_with_stdio(0); cin.tie(0);
cout.setf(ios::fixed); cout.precision(0);
int n, s, t;
cin >> n >> s >> t;
dp[1][1] = 1;
for(int i = 1; i < n; i++)
for(int j = 1; j <= i; j++){
if(i + 1 == s or i + 1 == t){
dp[i+1][j] = add(dp[i + 1][j], dp[i][j]);
dp[i+1][j+1] = add(dp[i + 1][j + 1], dp[i][j]);
continue;
}
dp[i+1][j-1] = add(dp[i+1][j-1], mul(dp[i][j], j-1));
dp[i+1][j+1] = add(dp[i+1][j+1], mul(dp[i][j], j + 1 - (int)(i >= s) - (int)(i >= t)));
}
cout << dp[n][1];
return 0;
}
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
0 ms |
332 KB |
Output is correct |
2 |
Correct |
0 ms |
332 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
0 ms |
332 KB |
Output is correct |
2 |
Correct |
0 ms |
332 KB |
Output is correct |
3 |
Correct |
1 ms |
332 KB |
Output is correct |
4 |
Correct |
1 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 |
460 KB |
Output is correct |
8 |
Correct |
1 ms |
452 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 |
460 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
0 ms |
332 KB |
Output is correct |
2 |
Correct |
0 ms |
332 KB |
Output is correct |
3 |
Correct |
1 ms |
332 KB |
Output is correct |
4 |
Correct |
1 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 |
460 KB |
Output is correct |
8 |
Correct |
1 ms |
452 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 |
460 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 |
1 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 |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
0 ms |
332 KB |
Output is correct |
2 |
Correct |
0 ms |
332 KB |
Output is correct |
3 |
Correct |
1 ms |
332 KB |
Output is correct |
4 |
Correct |
1 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 |
460 KB |
Output is correct |
8 |
Correct |
1 ms |
452 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 |
460 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 |
1 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 |
5 ms |
4556 KB |
Output is correct |
22 |
Correct |
5 ms |
5068 KB |
Output is correct |
23 |
Correct |
6 ms |
5580 KB |
Output is correct |
24 |
Correct |
29 ms |
22980 KB |
Output is correct |
25 |
Correct |
28 ms |
22964 KB |
Output is correct |
26 |
Correct |
28 ms |
22924 KB |
Output is correct |
27 |
Correct |
28 ms |
22916 KB |
Output is correct |
28 |
Correct |
17 ms |
15120 KB |
Output is correct |