#include<bits/stdc++.h>
using namespace std;
const int maxn=2002;
const int mod=1e9+7;
int fact[2*maxn];
int invf[2*maxn];
int dp[maxn][maxn];
int n,m;
int Mul(int a, int b) {
return 1ll*a*b%mod;
}
int Add(int a, int b) {
if(a+b>=mod) return a+b-mod;
return a+b;
}
int Bpow(int a, int b) {
int res=1;
int cur=a;
while(b) {
if(b&1) res=Mul(res,cur);
cur=Mul(cur,cur);
b/=2;
}
return res;
}
void init() {
fact[0]=fact[1]=1;
invf[0]=invf[1]=1;
for(int i=2 ; i<2*maxn ; i++) {
fact[i]=Mul(fact[i-1],i);
invf[i]=Bpow(fact[i],mod-2);
}
}
int C(int k, int n) {
if(k>n) return 0;
return Mul(fact[n],Mul(invf[n-k],invf[k]));
}
signed main() {
cin>>n>>m;
init();
dp[0][0]=1;
int rem=(2*n)%m;
for(int i=1 ; i<=m ; i++) {
int n_i=(2*n)/m+(i<=rem);
for(int j=0 ; j<=n ; j++) {
for(int k=0 ; 2*k<=n_i&&k<=j ; k++) {
int add=dp[i-1][j-k];
add=Mul(add,fact[n_i]); add=Mul(add,invf[n_i-2*k]);
add=Mul(add,C(k,j));
dp[i][j]=Add(dp[i][j],add);
}
}
}
int ans=fact[2*n];
for(int i=1 ; i<=n ; i++) {
int add=Mul(C(i,n),dp[m][i]);
add=Mul(add,fact[2*n-2*i]);
if(i&1) {
ans-=add;
if(ans<0) ans+=mod;
}
else {
ans+=add;
if(ans>=mod) ans-=mod;
}
}
cout<<ans;
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
332 KB |
Output is correct |
2 |
Correct |
1 ms |
332 KB |
Output is correct |
3 |
Correct |
1 ms |
332 KB |
Output is correct |
4 |
Correct |
1 ms |
332 KB |
Output is correct |
5 |
Correct |
1 ms |
332 KB |
Output is correct |
6 |
Correct |
1 ms |
332 KB |
Output is correct |
7 |
Correct |
1 ms |
332 KB |
Output is correct |
8 |
Correct |
1 ms |
332 KB |
Output is correct |
9 |
Correct |
1 ms |
332 KB |
Output is correct |
10 |
Correct |
1 ms |
332 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
332 KB |
Output is correct |
2 |
Correct |
1 ms |
332 KB |
Output is correct |
3 |
Correct |
1 ms |
332 KB |
Output is correct |
4 |
Correct |
1 ms |
332 KB |
Output is correct |
5 |
Correct |
1 ms |
332 KB |
Output is correct |
6 |
Correct |
1 ms |
332 KB |
Output is correct |
7 |
Correct |
1 ms |
332 KB |
Output is correct |
8 |
Correct |
1 ms |
332 KB |
Output is correct |
9 |
Correct |
1 ms |
332 KB |
Output is correct |
10 |
Correct |
1 ms |
332 KB |
Output is correct |
11 |
Correct |
1 ms |
460 KB |
Output is correct |
12 |
Correct |
2 ms |
460 KB |
Output is correct |
13 |
Correct |
1 ms |
332 KB |
Output is correct |
14 |
Correct |
1 ms |
332 KB |
Output is correct |
15 |
Correct |
1 ms |
588 KB |
Output is correct |
16 |
Correct |
1 ms |
332 KB |
Output is correct |
17 |
Correct |
1 ms |
460 KB |
Output is correct |
18 |
Correct |
1 ms |
460 KB |
Output is correct |
19 |
Correct |
1 ms |
332 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
332 KB |
Output is correct |
2 |
Correct |
1 ms |
332 KB |
Output is correct |
3 |
Correct |
1 ms |
332 KB |
Output is correct |
4 |
Correct |
1 ms |
332 KB |
Output is correct |
5 |
Correct |
1 ms |
332 KB |
Output is correct |
6 |
Correct |
1 ms |
332 KB |
Output is correct |
7 |
Correct |
1 ms |
332 KB |
Output is correct |
8 |
Correct |
1 ms |
332 KB |
Output is correct |
9 |
Correct |
1 ms |
332 KB |
Output is correct |
10 |
Correct |
1 ms |
332 KB |
Output is correct |
11 |
Correct |
1 ms |
460 KB |
Output is correct |
12 |
Correct |
2 ms |
460 KB |
Output is correct |
13 |
Correct |
1 ms |
332 KB |
Output is correct |
14 |
Correct |
1 ms |
332 KB |
Output is correct |
15 |
Correct |
1 ms |
588 KB |
Output is correct |
16 |
Correct |
1 ms |
332 KB |
Output is correct |
17 |
Correct |
1 ms |
460 KB |
Output is correct |
18 |
Correct |
1 ms |
460 KB |
Output is correct |
19 |
Correct |
1 ms |
332 KB |
Output is correct |
20 |
Correct |
1 ms |
332 KB |
Output is correct |
21 |
Correct |
2 ms |
712 KB |
Output is correct |
22 |
Correct |
3 ms |
1612 KB |
Output is correct |
23 |
Correct |
2 ms |
332 KB |
Output is correct |
24 |
Correct |
3 ms |
972 KB |
Output is correct |
25 |
Correct |
3 ms |
1484 KB |
Output is correct |
26 |
Correct |
2 ms |
320 KB |
Output is correct |
27 |
Correct |
4 ms |
1832 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
332 KB |
Output is correct |
2 |
Correct |
1 ms |
332 KB |
Output is correct |
3 |
Correct |
1 ms |
332 KB |
Output is correct |
4 |
Correct |
1 ms |
332 KB |
Output is correct |
5 |
Correct |
1 ms |
332 KB |
Output is correct |
6 |
Correct |
1 ms |
332 KB |
Output is correct |
7 |
Correct |
1 ms |
332 KB |
Output is correct |
8 |
Correct |
1 ms |
332 KB |
Output is correct |
9 |
Correct |
1 ms |
332 KB |
Output is correct |
10 |
Correct |
1 ms |
332 KB |
Output is correct |
11 |
Correct |
1 ms |
460 KB |
Output is correct |
12 |
Correct |
2 ms |
460 KB |
Output is correct |
13 |
Correct |
1 ms |
332 KB |
Output is correct |
14 |
Correct |
1 ms |
332 KB |
Output is correct |
15 |
Correct |
1 ms |
588 KB |
Output is correct |
16 |
Correct |
1 ms |
332 KB |
Output is correct |
17 |
Correct |
1 ms |
460 KB |
Output is correct |
18 |
Correct |
1 ms |
460 KB |
Output is correct |
19 |
Correct |
1 ms |
332 KB |
Output is correct |
20 |
Correct |
1 ms |
332 KB |
Output is correct |
21 |
Correct |
2 ms |
712 KB |
Output is correct |
22 |
Correct |
3 ms |
1612 KB |
Output is correct |
23 |
Correct |
2 ms |
332 KB |
Output is correct |
24 |
Correct |
3 ms |
972 KB |
Output is correct |
25 |
Correct |
3 ms |
1484 KB |
Output is correct |
26 |
Correct |
2 ms |
320 KB |
Output is correct |
27 |
Correct |
4 ms |
1832 KB |
Output is correct |
28 |
Correct |
6 ms |
332 KB |
Output is correct |
29 |
Correct |
12 ms |
2424 KB |
Output is correct |
30 |
Correct |
18 ms |
4128 KB |
Output is correct |
31 |
Correct |
6 ms |
408 KB |
Output is correct |
32 |
Correct |
11 ms |
2508 KB |
Output is correct |
33 |
Correct |
15 ms |
4636 KB |
Output is correct |
34 |
Correct |
25 ms |
7028 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
332 KB |
Output is correct |
2 |
Correct |
1 ms |
332 KB |
Output is correct |
3 |
Correct |
1 ms |
332 KB |
Output is correct |
4 |
Correct |
1 ms |
332 KB |
Output is correct |
5 |
Correct |
1 ms |
332 KB |
Output is correct |
6 |
Correct |
1 ms |
332 KB |
Output is correct |
7 |
Correct |
1 ms |
332 KB |
Output is correct |
8 |
Correct |
1 ms |
332 KB |
Output is correct |
9 |
Correct |
1 ms |
332 KB |
Output is correct |
10 |
Correct |
1 ms |
332 KB |
Output is correct |
11 |
Correct |
1 ms |
460 KB |
Output is correct |
12 |
Correct |
2 ms |
460 KB |
Output is correct |
13 |
Correct |
1 ms |
332 KB |
Output is correct |
14 |
Correct |
1 ms |
332 KB |
Output is correct |
15 |
Correct |
1 ms |
588 KB |
Output is correct |
16 |
Correct |
1 ms |
332 KB |
Output is correct |
17 |
Correct |
1 ms |
460 KB |
Output is correct |
18 |
Correct |
1 ms |
460 KB |
Output is correct |
19 |
Correct |
1 ms |
332 KB |
Output is correct |
20 |
Correct |
1 ms |
332 KB |
Output is correct |
21 |
Correct |
2 ms |
712 KB |
Output is correct |
22 |
Correct |
3 ms |
1612 KB |
Output is correct |
23 |
Correct |
2 ms |
332 KB |
Output is correct |
24 |
Correct |
3 ms |
972 KB |
Output is correct |
25 |
Correct |
3 ms |
1484 KB |
Output is correct |
26 |
Correct |
2 ms |
320 KB |
Output is correct |
27 |
Correct |
4 ms |
1832 KB |
Output is correct |
28 |
Correct |
6 ms |
332 KB |
Output is correct |
29 |
Correct |
12 ms |
2424 KB |
Output is correct |
30 |
Correct |
18 ms |
4128 KB |
Output is correct |
31 |
Correct |
6 ms |
408 KB |
Output is correct |
32 |
Correct |
11 ms |
2508 KB |
Output is correct |
33 |
Correct |
15 ms |
4636 KB |
Output is correct |
34 |
Correct |
25 ms |
7028 KB |
Output is correct |
35 |
Correct |
35 ms |
380 KB |
Output is correct |
36 |
Correct |
85 ms |
13420 KB |
Output is correct |
37 |
Correct |
31 ms |
456 KB |
Output is correct |
38 |
Correct |
52 ms |
6612 KB |
Output is correct |
39 |
Correct |
76 ms |
12060 KB |
Output is correct |
40 |
Correct |
133 ms |
15896 KB |
Output is correct |