#include<bits/stdc++.h>
using namespace std;
const long long MOD = 1e9 + 7;
const long long maxn = 2000;
long long fac[maxn * 2 + 100];
long long fiv[maxn * 2 + 100];
long long ml(long long x, long long y){
return (x * y) % MOD;
}
long long pow_mod(long long x,long long y){
if (y == 0)return 1;
long long r = pow_mod(x,y/2);
r = ml(r,r);
if (y % 2)r = ml(r,x);
return r;
}
long long dp[maxn + 100][maxn + 100];
long long choose(long long k,long long n){
return ml(ml(fac[n],fiv[k]),fiv[n - k]);
}
long long n,m;
int main(){
//freopen("NOM.INP","r",stdin);
//freopen("NOM.OUT","w",stdout);
fac[0] = 1;
for (long long i = 1;i <= 2 * maxn;i ++){
fac[i] = ml(fac[i-1],i);
}
fiv[maxn * 2] = pow_mod(fac[2 * maxn],MOD - 2);
for (long long i = maxn * 2 - 1;i >= 0;i --){
fiv[i] = ml(fiv[i + 1],i + 1);
}
cin>>n>>m;
dp[0][0] = 1;
dp[0][1] = 0;
for (long long i = 1;i <= m;i ++){
long long am;
if (i <= (2 * n) % m){
am = (2 * n) / m + 1;
}
else{
am = (2 * n) / m;
}
long long buck = am / 2;
for (long long j = 0;j <= n;j ++){
for (long long k = 0;k <= j && k <= buck;k ++){
dp[i][j] += ml(ml(ml(dp[i - 1][j - k], choose(k * 2,am)),fac[k*2]),fiv[k]);
dp[i][j] %= MOD;
}
}
}
long long ans = 1;
for (long long i = 1;i <= 2 * n;i ++){
ans = ml(ans,i);
}
for (long long j = 1;j <= n;j ++){
//cout<<dp[m][j]<<' ';
if (j % 2){
ans -= ml(fac[j],ml(ml(choose(j,n),dp[m][j]),fac[2 * (n - j)])) + MOD;
}
else{
ans += ml(fac[j],ml(ml(choose(j,n),dp[m][j]),fac[2 * (n - j)]));
}
ans %= MOD;
}
cout<<(ans + MOD) % MOD;
return 0;
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
460 KB |
Output is correct |
2 |
Correct |
0 ms |
332 KB |
Output is correct |
3 |
Correct |
1 ms |
368 KB |
Output is correct |
4 |
Correct |
0 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 |
0 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 |
460 KB |
Output is correct |
2 |
Correct |
0 ms |
332 KB |
Output is correct |
3 |
Correct |
1 ms |
368 KB |
Output is correct |
4 |
Correct |
0 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 |
0 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 |
624 KB |
Output is correct |
12 |
Correct |
1 ms |
588 KB |
Output is correct |
13 |
Correct |
1 ms |
332 KB |
Output is correct |
14 |
Correct |
1 ms |
500 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 |
496 KB |
Output is correct |
18 |
Correct |
1 ms |
588 KB |
Output is correct |
19 |
Correct |
1 ms |
332 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
460 KB |
Output is correct |
2 |
Correct |
0 ms |
332 KB |
Output is correct |
3 |
Correct |
1 ms |
368 KB |
Output is correct |
4 |
Correct |
0 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 |
0 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 |
624 KB |
Output is correct |
12 |
Correct |
1 ms |
588 KB |
Output is correct |
13 |
Correct |
1 ms |
332 KB |
Output is correct |
14 |
Correct |
1 ms |
500 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 |
496 KB |
Output is correct |
18 |
Correct |
1 ms |
588 KB |
Output is correct |
19 |
Correct |
1 ms |
332 KB |
Output is correct |
20 |
Correct |
1 ms |
364 KB |
Output is correct |
21 |
Correct |
1 ms |
716 KB |
Output is correct |
22 |
Correct |
3 ms |
1868 KB |
Output is correct |
23 |
Correct |
1 ms |
360 KB |
Output is correct |
24 |
Correct |
2 ms |
1228 KB |
Output is correct |
25 |
Correct |
3 ms |
1772 KB |
Output is correct |
26 |
Correct |
2 ms |
460 KB |
Output is correct |
27 |
Correct |
4 ms |
2252 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
460 KB |
Output is correct |
2 |
Correct |
0 ms |
332 KB |
Output is correct |
3 |
Correct |
1 ms |
368 KB |
Output is correct |
4 |
Correct |
0 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 |
0 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 |
624 KB |
Output is correct |
12 |
Correct |
1 ms |
588 KB |
Output is correct |
13 |
Correct |
1 ms |
332 KB |
Output is correct |
14 |
Correct |
1 ms |
500 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 |
496 KB |
Output is correct |
18 |
Correct |
1 ms |
588 KB |
Output is correct |
19 |
Correct |
1 ms |
332 KB |
Output is correct |
20 |
Correct |
1 ms |
364 KB |
Output is correct |
21 |
Correct |
1 ms |
716 KB |
Output is correct |
22 |
Correct |
3 ms |
1868 KB |
Output is correct |
23 |
Correct |
1 ms |
360 KB |
Output is correct |
24 |
Correct |
2 ms |
1228 KB |
Output is correct |
25 |
Correct |
3 ms |
1772 KB |
Output is correct |
26 |
Correct |
2 ms |
460 KB |
Output is correct |
27 |
Correct |
4 ms |
2252 KB |
Output is correct |
28 |
Correct |
6 ms |
460 KB |
Output is correct |
29 |
Correct |
11 ms |
3276 KB |
Output is correct |
30 |
Correct |
14 ms |
5580 KB |
Output is correct |
31 |
Correct |
6 ms |
356 KB |
Output is correct |
32 |
Correct |
17 ms |
3484 KB |
Output is correct |
33 |
Correct |
17 ms |
6448 KB |
Output is correct |
34 |
Correct |
28 ms |
10180 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
460 KB |
Output is correct |
2 |
Correct |
0 ms |
332 KB |
Output is correct |
3 |
Correct |
1 ms |
368 KB |
Output is correct |
4 |
Correct |
0 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 |
0 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 |
624 KB |
Output is correct |
12 |
Correct |
1 ms |
588 KB |
Output is correct |
13 |
Correct |
1 ms |
332 KB |
Output is correct |
14 |
Correct |
1 ms |
500 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 |
496 KB |
Output is correct |
18 |
Correct |
1 ms |
588 KB |
Output is correct |
19 |
Correct |
1 ms |
332 KB |
Output is correct |
20 |
Correct |
1 ms |
364 KB |
Output is correct |
21 |
Correct |
1 ms |
716 KB |
Output is correct |
22 |
Correct |
3 ms |
1868 KB |
Output is correct |
23 |
Correct |
1 ms |
360 KB |
Output is correct |
24 |
Correct |
2 ms |
1228 KB |
Output is correct |
25 |
Correct |
3 ms |
1772 KB |
Output is correct |
26 |
Correct |
2 ms |
460 KB |
Output is correct |
27 |
Correct |
4 ms |
2252 KB |
Output is correct |
28 |
Correct |
6 ms |
460 KB |
Output is correct |
29 |
Correct |
11 ms |
3276 KB |
Output is correct |
30 |
Correct |
14 ms |
5580 KB |
Output is correct |
31 |
Correct |
6 ms |
356 KB |
Output is correct |
32 |
Correct |
17 ms |
3484 KB |
Output is correct |
33 |
Correct |
17 ms |
6448 KB |
Output is correct |
34 |
Correct |
28 ms |
10180 KB |
Output is correct |
35 |
Correct |
34 ms |
616 KB |
Output is correct |
36 |
Correct |
99 ms |
27984 KB |
Output is correct |
37 |
Correct |
40 ms |
612 KB |
Output is correct |
38 |
Correct |
71 ms |
13712 KB |
Output is correct |
39 |
Correct |
80 ms |
24800 KB |
Output is correct |
40 |
Correct |
125 ms |
33180 KB |
Output is correct |