// And you curse yourself for things you never done
#include<bits/stdc++.h>
#define F first
#define S second
#define PB push_back
#define sz(s) int((s).size())
#define bit(n,k) (((n)>>(k))&1)
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
const int maxn = 1220, mod = 1e9 + 7, inf = 1e9 + 10;
int dp[maxn][maxn], C[maxn][maxn];
bool is[maxn];
int dp2[maxn][maxn], F[maxn];
int main(){
ios_base::sync_with_stdio(false); cin.tie(0); cout.tie();
for(int i = 0; i < maxn; i++){
C[i][i] = C[i][0] = 1;
for(int j = 1; j < i; j++)
C[i][j] = (C[i-1][j] + C[i-1][j-1]) % mod;
}
dp2[0][0] = 1;
for(int i = 1; i < maxn; i++){
for(int j = 0; j <= i; j++){
if(j + 2 <= i)
dp2[i][j] = (1ll * dp2[i][j] + 1ll * C[i-j][2] * dp2[i-1][j+1]) % mod;
if(j >= 1)
dp2[i][j] = (1ll * dp2[i][j] + 1ll * C[i+j][2] * dp2[i-1][j-1]) % mod;
if(j < i)
dp2[i][j] = (1ll * dp2[i][j] + 1ll * (i-j) * (i+j) % mod * dp2[i-1][j]) % mod;
}
}
for(int i = 1; i < maxn; i++){
F[i] = dp2[i][0];
for(int j = 1; j < i; j++){
F[i] = (1ll * F[i] - 1ll * C[i-1][j-1] %mod * C[i][j] %mod * F[j] % mod * dp2[i-j][0]) % mod;
}
F[i] = (F[i] + mod) % mod;
}
int n;
cin >> n;
for(int i = 1; i <= n; i++){
int x;
cin >> x;
is[x] = 1;
}
int cnt = 0;
for(int i = 2*n; i >= 1; i--){
cnt+= is[i] ? 1 : -1;
if(cnt < 0)
return cout << 0 << endl, 0;
}
dp[0][0] = 1;
for(int i = 1; i <= n; i++){
int A = 0, B = 0;
for(int j = 2*n; j >= 1; j--){
if(is[j]){
if(++A == i)
break;
}
else{
++B;
}
}
for(int j = i; j >= 0; j--){
if(B > i-j)
continue;
int extra = i-j - B;
if(j > 0)
dp[i][j] = (dp[i][j] + dp[i-1][j-1]) % mod;
for(int k = 1; k + j <= i && k <= extra; k++){
dp[i][j] = (1ll * dp[i][j] + 1ll * C[j + k-1][k-1] * F[k] % mod * C[extra][k] % mod * dp[i-1][j + k-1]) % mod;
}
}
}
return cout << dp[n][0] << endl, 0;
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
30 ms |
11896 KB |
Output is correct |
2 |
Correct |
30 ms |
11896 KB |
Output is correct |
3 |
Correct |
30 ms |
11896 KB |
Output is correct |
4 |
Correct |
29 ms |
11896 KB |
Output is correct |
5 |
Correct |
30 ms |
11904 KB |
Output is correct |
6 |
Correct |
32 ms |
11896 KB |
Output is correct |
7 |
Correct |
30 ms |
11904 KB |
Output is correct |
8 |
Correct |
30 ms |
11936 KB |
Output is correct |
9 |
Correct |
32 ms |
11896 KB |
Output is correct |
10 |
Correct |
30 ms |
11896 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
30 ms |
11896 KB |
Output is correct |
2 |
Correct |
30 ms |
11896 KB |
Output is correct |
3 |
Correct |
30 ms |
11896 KB |
Output is correct |
4 |
Correct |
29 ms |
11896 KB |
Output is correct |
5 |
Correct |
30 ms |
11904 KB |
Output is correct |
6 |
Correct |
32 ms |
11896 KB |
Output is correct |
7 |
Correct |
30 ms |
11904 KB |
Output is correct |
8 |
Correct |
30 ms |
11936 KB |
Output is correct |
9 |
Correct |
32 ms |
11896 KB |
Output is correct |
10 |
Correct |
30 ms |
11896 KB |
Output is correct |
11 |
Correct |
30 ms |
12024 KB |
Output is correct |
12 |
Correct |
33 ms |
12104 KB |
Output is correct |
13 |
Correct |
30 ms |
12032 KB |
Output is correct |
14 |
Correct |
30 ms |
11896 KB |
Output is correct |
15 |
Correct |
37 ms |
11896 KB |
Output is correct |
16 |
Correct |
30 ms |
12024 KB |
Output is correct |
17 |
Correct |
34 ms |
11896 KB |
Output is correct |
18 |
Correct |
37 ms |
12024 KB |
Output is correct |
19 |
Correct |
31 ms |
12032 KB |
Output is correct |
20 |
Correct |
32 ms |
12024 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
30 ms |
11896 KB |
Output is correct |
2 |
Correct |
30 ms |
11896 KB |
Output is correct |
3 |
Correct |
30 ms |
11896 KB |
Output is correct |
4 |
Correct |
29 ms |
11896 KB |
Output is correct |
5 |
Correct |
30 ms |
11904 KB |
Output is correct |
6 |
Correct |
32 ms |
11896 KB |
Output is correct |
7 |
Correct |
30 ms |
11904 KB |
Output is correct |
8 |
Correct |
30 ms |
11936 KB |
Output is correct |
9 |
Correct |
32 ms |
11896 KB |
Output is correct |
10 |
Correct |
30 ms |
11896 KB |
Output is correct |
11 |
Correct |
30 ms |
12024 KB |
Output is correct |
12 |
Correct |
33 ms |
12104 KB |
Output is correct |
13 |
Correct |
30 ms |
12032 KB |
Output is correct |
14 |
Correct |
30 ms |
11896 KB |
Output is correct |
15 |
Correct |
37 ms |
11896 KB |
Output is correct |
16 |
Correct |
30 ms |
12024 KB |
Output is correct |
17 |
Correct |
34 ms |
11896 KB |
Output is correct |
18 |
Correct |
37 ms |
12024 KB |
Output is correct |
19 |
Correct |
31 ms |
12032 KB |
Output is correct |
20 |
Correct |
32 ms |
12024 KB |
Output is correct |
21 |
Correct |
34 ms |
14328 KB |
Output is correct |
22 |
Correct |
33 ms |
14328 KB |
Output is correct |
23 |
Correct |
40 ms |
14328 KB |
Output is correct |
24 |
Correct |
36 ms |
14328 KB |
Output is correct |
25 |
Correct |
38 ms |
11900 KB |
Output is correct |
26 |
Correct |
30 ms |
11896 KB |
Output is correct |
27 |
Correct |
30 ms |
11904 KB |
Output is correct |
28 |
Correct |
33 ms |
14200 KB |
Output is correct |
29 |
Correct |
30 ms |
11812 KB |
Output is correct |
30 |
Correct |
370 ms |
14584 KB |
Output is correct |
31 |
Correct |
198 ms |
14572 KB |
Output is correct |
32 |
Correct |
271 ms |
14584 KB |
Output is correct |
33 |
Correct |
346 ms |
14584 KB |
Output is correct |
34 |
Correct |
197 ms |
14712 KB |
Output is correct |
35 |
Correct |
278 ms |
14764 KB |
Output is correct |
36 |
Correct |
343 ms |
14584 KB |
Output is correct |