#include <bits/stdc++.h>
#define maxn 2024
using namespace std;
const int mod = 1000000007;
int n, cs, cf;
int dp[maxn][maxn];
int main() {
cin.tie(0); ios_base::sync_with_stdio(false);
cin>>n>>cs>>cf;
if(n==2) {
cout<<1<<endl;
return 0;
}
if(cf==1 || cs==1) dp[1][0]=1;
else dp[1][1] = 1;
for(int i=2;i<=n;i++) {
for(long long g=0;g<=i;g++) {
if(i<cs && i<cf) {
dp[i][g] = ((g?dp[i-1][g-1]:0) + g*(g+1)*dp[i-1][g+1])%mod;
continue;
}
if(i==cs || i==cf) {
dp[i][g] = (dp[i-1][g] + (g+1)*dp[i-1][g+1])%mod;
continue;
}
if(i>cf && i>cs) {
dp[i][g] = ((g?dp[i-1][g-1]:0) + (g+2)*(g+1)*dp[i-1][g+1])%mod;
continue;
}
else {
dp[i][g] = ((g?dp[i-1][g-1]:0) + (g+1)*(g+1)*dp[i-1][g+1])%mod;
continue;
}
}
}
cout<<dp[n-1][0]<<endl;
return 0;
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
0 ms |
348 KB |
Output is correct |
2 |
Correct |
0 ms |
348 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
0 ms |
348 KB |
Output is correct |
2 |
Correct |
0 ms |
348 KB |
Output is correct |
3 |
Correct |
1 ms |
2396 KB |
Output is correct |
4 |
Correct |
0 ms |
2396 KB |
Output is correct |
5 |
Correct |
0 ms |
2396 KB |
Output is correct |
6 |
Correct |
1 ms |
2392 KB |
Output is correct |
7 |
Correct |
1 ms |
2392 KB |
Output is correct |
8 |
Correct |
0 ms |
2396 KB |
Output is correct |
9 |
Correct |
1 ms |
2396 KB |
Output is correct |
10 |
Correct |
0 ms |
2396 KB |
Output is correct |
11 |
Correct |
1 ms |
2392 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
0 ms |
348 KB |
Output is correct |
2 |
Correct |
0 ms |
348 KB |
Output is correct |
3 |
Correct |
1 ms |
2396 KB |
Output is correct |
4 |
Correct |
0 ms |
2396 KB |
Output is correct |
5 |
Correct |
0 ms |
2396 KB |
Output is correct |
6 |
Correct |
1 ms |
2392 KB |
Output is correct |
7 |
Correct |
1 ms |
2392 KB |
Output is correct |
8 |
Correct |
0 ms |
2396 KB |
Output is correct |
9 |
Correct |
1 ms |
2396 KB |
Output is correct |
10 |
Correct |
0 ms |
2396 KB |
Output is correct |
11 |
Correct |
1 ms |
2392 KB |
Output is correct |
12 |
Correct |
1 ms |
2396 KB |
Output is correct |
13 |
Correct |
0 ms |
2396 KB |
Output is correct |
14 |
Correct |
1 ms |
2396 KB |
Output is correct |
15 |
Correct |
0 ms |
2396 KB |
Output is correct |
16 |
Correct |
1 ms |
2396 KB |
Output is correct |
17 |
Correct |
1 ms |
2392 KB |
Output is correct |
18 |
Correct |
1 ms |
2396 KB |
Output is correct |
19 |
Correct |
1 ms |
2396 KB |
Output is correct |
20 |
Correct |
1 ms |
2396 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
0 ms |
348 KB |
Output is correct |
2 |
Correct |
0 ms |
348 KB |
Output is correct |
3 |
Correct |
1 ms |
2396 KB |
Output is correct |
4 |
Correct |
0 ms |
2396 KB |
Output is correct |
5 |
Correct |
0 ms |
2396 KB |
Output is correct |
6 |
Correct |
1 ms |
2392 KB |
Output is correct |
7 |
Correct |
1 ms |
2392 KB |
Output is correct |
8 |
Correct |
0 ms |
2396 KB |
Output is correct |
9 |
Correct |
1 ms |
2396 KB |
Output is correct |
10 |
Correct |
0 ms |
2396 KB |
Output is correct |
11 |
Correct |
1 ms |
2392 KB |
Output is correct |
12 |
Correct |
1 ms |
2396 KB |
Output is correct |
13 |
Correct |
0 ms |
2396 KB |
Output is correct |
14 |
Correct |
1 ms |
2396 KB |
Output is correct |
15 |
Correct |
0 ms |
2396 KB |
Output is correct |
16 |
Correct |
1 ms |
2396 KB |
Output is correct |
17 |
Correct |
1 ms |
2392 KB |
Output is correct |
18 |
Correct |
1 ms |
2396 KB |
Output is correct |
19 |
Correct |
1 ms |
2396 KB |
Output is correct |
20 |
Correct |
1 ms |
2396 KB |
Output is correct |
21 |
Correct |
2 ms |
6492 KB |
Output is correct |
22 |
Correct |
1 ms |
6492 KB |
Output is correct |
23 |
Correct |
2 ms |
6716 KB |
Output is correct |
24 |
Correct |
7 ms |
16204 KB |
Output is correct |
25 |
Correct |
7 ms |
16216 KB |
Output is correct |
26 |
Correct |
9 ms |
16220 KB |
Output is correct |
27 |
Correct |
10 ms |
15960 KB |
Output is correct |
28 |
Correct |
4 ms |
12636 KB |
Output is correct |