#include <bits/stdc++.h>
#define int long long
using namespace std;
const int Mod = 1e9 + 7;
const int vmax = 1e4;
int n,m;
int fact[vmax + 5], invfact[vmax + 5];
int dp[2005],aux[2005];
int nr[2005];
int lgput(int a, int b)
{
int p = 1;
while(b)
{
if(b % 2 == 0)
{
b/=2;
a = 1LL * a * a % Mod;
}
else
{
--b;
p = 1LL * p * a % Mod;
}
}
return p;
}
int invmod(int x)
{
return lgput(x,Mod-2) % Mod;
}
int comb(int n, int k)
{
return 1LL * fact[n] * invfact[k] % Mod * invfact[n - k] % Mod;
}
int aranj(int n, int k)
{
return 1LL * fact[n] * invfact[n - k] % Mod;
}
void precalc()
{
fact[0] = 1;
for(int i=1;i<=vmax;i++)
{
fact[i] = 1LL * fact[i-1] * i % Mod;
}
invfact[vmax] = invmod(fact[vmax]);
for(int i=vmax-1;i>=0;i--)
{
invfact[i] = 1LL * invfact[i + 1] * (i + 1) % Mod;
}
}
void calc_dp()
{
int nr_tot = (2 * n) / m;
int rest = (2 * n) % m;
for(int r=0;r<m;r++)
{
nr[r] = nr_tot;
if(r<=rest && r!=0)
{
++nr[r];
}
}
for(int i=0;2*i<=nr[0];i++)
{
dp[i] = aranj(nr[0],2*i) * invfact[i] % Mod;
}
int Max = nr[0] / 2;
for(int r=1;r<m;r++)
{
for(int i=0;i<=Max;i++)
{
aux[i] = 0;
}
for(int i=0;i<=Max;i++)
{
for(int j=0;2*j<=nr[r] && i+j<=Max+nr[r]/2;j++)
{
aux[i + j] += dp[i] * aranj(nr[r],2*j) % Mod * invfact[j] % Mod;
aux[i + j] %= Mod;
}
}
for(int i=0;i<=n;i++)
{
dp[i] = aux[i];
}
Max += nr[r] / 2;
}
}
signed main()
{
cin>>n>>m;
precalc();
calc_dp();
int rez = 0;
for(int i=0;i<=n;i++)
{
if(i % 2 == 0)
{
rez += dp[i] * fact[2 * (n - i)] % Mod * aranj(n,i) % Mod;
rez %= Mod;
}
else
{
rez -= dp[i] * fact[2 * (n - i)] % Mod * aranj(n,i) % Mod;
rez %= Mod;
if(rez < 0)
{
rez += Mod;
}
}
}
cout<<rez<<'\n';
return 0;
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
432 KB |
Output is correct |
2 |
Correct |
1 ms |
436 KB |
Output is correct |
3 |
Correct |
1 ms |
468 KB |
Output is correct |
4 |
Correct |
1 ms |
468 KB |
Output is correct |
5 |
Correct |
1 ms |
468 KB |
Output is correct |
6 |
Correct |
1 ms |
436 KB |
Output is correct |
7 |
Correct |
1 ms |
468 KB |
Output is correct |
8 |
Correct |
1 ms |
468 KB |
Output is correct |
9 |
Correct |
1 ms |
436 KB |
Output is correct |
10 |
Correct |
1 ms |
432 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
432 KB |
Output is correct |
2 |
Correct |
1 ms |
436 KB |
Output is correct |
3 |
Correct |
1 ms |
468 KB |
Output is correct |
4 |
Correct |
1 ms |
468 KB |
Output is correct |
5 |
Correct |
1 ms |
468 KB |
Output is correct |
6 |
Correct |
1 ms |
436 KB |
Output is correct |
7 |
Correct |
1 ms |
468 KB |
Output is correct |
8 |
Correct |
1 ms |
468 KB |
Output is correct |
9 |
Correct |
1 ms |
436 KB |
Output is correct |
10 |
Correct |
1 ms |
432 KB |
Output is correct |
11 |
Correct |
1 ms |
468 KB |
Output is correct |
12 |
Correct |
1 ms |
468 KB |
Output is correct |
13 |
Correct |
1 ms |
468 KB |
Output is correct |
14 |
Correct |
1 ms |
468 KB |
Output is correct |
15 |
Correct |
1 ms |
468 KB |
Output is correct |
16 |
Correct |
1 ms |
432 KB |
Output is correct |
17 |
Correct |
1 ms |
468 KB |
Output is correct |
18 |
Correct |
1 ms |
468 KB |
Output is correct |
19 |
Correct |
1 ms |
436 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
432 KB |
Output is correct |
2 |
Correct |
1 ms |
436 KB |
Output is correct |
3 |
Correct |
1 ms |
468 KB |
Output is correct |
4 |
Correct |
1 ms |
468 KB |
Output is correct |
5 |
Correct |
1 ms |
468 KB |
Output is correct |
6 |
Correct |
1 ms |
436 KB |
Output is correct |
7 |
Correct |
1 ms |
468 KB |
Output is correct |
8 |
Correct |
1 ms |
468 KB |
Output is correct |
9 |
Correct |
1 ms |
436 KB |
Output is correct |
10 |
Correct |
1 ms |
432 KB |
Output is correct |
11 |
Correct |
1 ms |
468 KB |
Output is correct |
12 |
Correct |
1 ms |
468 KB |
Output is correct |
13 |
Correct |
1 ms |
468 KB |
Output is correct |
14 |
Correct |
1 ms |
468 KB |
Output is correct |
15 |
Correct |
1 ms |
468 KB |
Output is correct |
16 |
Correct |
1 ms |
432 KB |
Output is correct |
17 |
Correct |
1 ms |
468 KB |
Output is correct |
18 |
Correct |
1 ms |
468 KB |
Output is correct |
19 |
Correct |
1 ms |
436 KB |
Output is correct |
20 |
Correct |
1 ms |
468 KB |
Output is correct |
21 |
Correct |
1 ms |
468 KB |
Output is correct |
22 |
Correct |
1 ms |
432 KB |
Output is correct |
23 |
Correct |
1 ms |
468 KB |
Output is correct |
24 |
Correct |
1 ms |
432 KB |
Output is correct |
25 |
Correct |
1 ms |
436 KB |
Output is correct |
26 |
Correct |
2 ms |
432 KB |
Output is correct |
27 |
Correct |
2 ms |
468 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
432 KB |
Output is correct |
2 |
Correct |
1 ms |
436 KB |
Output is correct |
3 |
Correct |
1 ms |
468 KB |
Output is correct |
4 |
Correct |
1 ms |
468 KB |
Output is correct |
5 |
Correct |
1 ms |
468 KB |
Output is correct |
6 |
Correct |
1 ms |
436 KB |
Output is correct |
7 |
Correct |
1 ms |
468 KB |
Output is correct |
8 |
Correct |
1 ms |
468 KB |
Output is correct |
9 |
Correct |
1 ms |
436 KB |
Output is correct |
10 |
Correct |
1 ms |
432 KB |
Output is correct |
11 |
Correct |
1 ms |
468 KB |
Output is correct |
12 |
Correct |
1 ms |
468 KB |
Output is correct |
13 |
Correct |
1 ms |
468 KB |
Output is correct |
14 |
Correct |
1 ms |
468 KB |
Output is correct |
15 |
Correct |
1 ms |
468 KB |
Output is correct |
16 |
Correct |
1 ms |
432 KB |
Output is correct |
17 |
Correct |
1 ms |
468 KB |
Output is correct |
18 |
Correct |
1 ms |
468 KB |
Output is correct |
19 |
Correct |
1 ms |
436 KB |
Output is correct |
20 |
Correct |
1 ms |
468 KB |
Output is correct |
21 |
Correct |
1 ms |
468 KB |
Output is correct |
22 |
Correct |
1 ms |
432 KB |
Output is correct |
23 |
Correct |
1 ms |
468 KB |
Output is correct |
24 |
Correct |
1 ms |
432 KB |
Output is correct |
25 |
Correct |
1 ms |
436 KB |
Output is correct |
26 |
Correct |
2 ms |
432 KB |
Output is correct |
27 |
Correct |
2 ms |
468 KB |
Output is correct |
28 |
Correct |
2 ms |
468 KB |
Output is correct |
29 |
Correct |
3 ms |
468 KB |
Output is correct |
30 |
Correct |
4 ms |
468 KB |
Output is correct |
31 |
Correct |
2 ms |
468 KB |
Output is correct |
32 |
Correct |
4 ms |
472 KB |
Output is correct |
33 |
Correct |
5 ms |
488 KB |
Output is correct |
34 |
Correct |
8 ms |
436 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
432 KB |
Output is correct |
2 |
Correct |
1 ms |
436 KB |
Output is correct |
3 |
Correct |
1 ms |
468 KB |
Output is correct |
4 |
Correct |
1 ms |
468 KB |
Output is correct |
5 |
Correct |
1 ms |
468 KB |
Output is correct |
6 |
Correct |
1 ms |
436 KB |
Output is correct |
7 |
Correct |
1 ms |
468 KB |
Output is correct |
8 |
Correct |
1 ms |
468 KB |
Output is correct |
9 |
Correct |
1 ms |
436 KB |
Output is correct |
10 |
Correct |
1 ms |
432 KB |
Output is correct |
11 |
Correct |
1 ms |
468 KB |
Output is correct |
12 |
Correct |
1 ms |
468 KB |
Output is correct |
13 |
Correct |
1 ms |
468 KB |
Output is correct |
14 |
Correct |
1 ms |
468 KB |
Output is correct |
15 |
Correct |
1 ms |
468 KB |
Output is correct |
16 |
Correct |
1 ms |
432 KB |
Output is correct |
17 |
Correct |
1 ms |
468 KB |
Output is correct |
18 |
Correct |
1 ms |
468 KB |
Output is correct |
19 |
Correct |
1 ms |
436 KB |
Output is correct |
20 |
Correct |
1 ms |
468 KB |
Output is correct |
21 |
Correct |
1 ms |
468 KB |
Output is correct |
22 |
Correct |
1 ms |
432 KB |
Output is correct |
23 |
Correct |
1 ms |
468 KB |
Output is correct |
24 |
Correct |
1 ms |
432 KB |
Output is correct |
25 |
Correct |
1 ms |
436 KB |
Output is correct |
26 |
Correct |
2 ms |
432 KB |
Output is correct |
27 |
Correct |
2 ms |
468 KB |
Output is correct |
28 |
Correct |
2 ms |
468 KB |
Output is correct |
29 |
Correct |
3 ms |
468 KB |
Output is correct |
30 |
Correct |
4 ms |
468 KB |
Output is correct |
31 |
Correct |
2 ms |
468 KB |
Output is correct |
32 |
Correct |
4 ms |
472 KB |
Output is correct |
33 |
Correct |
5 ms |
488 KB |
Output is correct |
34 |
Correct |
8 ms |
436 KB |
Output is correct |
35 |
Correct |
11 ms |
496 KB |
Output is correct |
36 |
Correct |
30 ms |
500 KB |
Output is correct |
37 |
Correct |
11 ms |
468 KB |
Output is correct |
38 |
Correct |
19 ms |
436 KB |
Output is correct |
39 |
Correct |
20 ms |
496 KB |
Output is correct |
40 |
Correct |
33 ms |
500 KB |
Output is correct |