#include <cstdio>
#include <algorithm>
const int p = 1000000007;
using namespace std;
int f(int x, int y)
{
return y & 1 ? (long long)f(x, y ^ 1)*x%p : y ? f((long long)x*x%p, y >> 1) : 1;
}
int fac[1000001];
int inv[1000001];
int main()
{
int i, j, n, m, r = 0;
scanf("%d%d", &n, &m);
fac[0] = 1;
for (i = 1; i <= n + 1; i++) fac[i] = (long long)fac[i - 1] * i % p;
inv[n + 1] = f(fac[n + 1], p - 2);
for (i = n + 1; i >= 1; i--) inv[i - 1] = (long long)inv[i] * i % p;
for (i = 0; i < n - m; i++)
{
j = fac[n - i];
j = (long long)j * fac[n - m + 1] % p;
j = (long long)j * inv[n - m - i - 1] % p;
j = (long long)j * f(i + 2, p - 2) % p;
r = (r + j) % p;
}
printf("%d", r);
}
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
0 ms |
8896 KB |
Output is correct |
| 2 |
Correct |
0 ms |
8896 KB |
Output is correct |
| 3 |
Correct |
0 ms |
8896 KB |
Output is correct |
| 4 |
Correct |
0 ms |
8896 KB |
Output is correct |
| 5 |
Correct |
0 ms |
8896 KB |
Output is correct |
| 6 |
Correct |
0 ms |
8896 KB |
Output is correct |
| 7 |
Correct |
0 ms |
8896 KB |
Output is correct |
| 8 |
Correct |
0 ms |
8896 KB |
Output is correct |
| 9 |
Correct |
0 ms |
8896 KB |
Output is correct |
| 10 |
Correct |
0 ms |
8896 KB |
Output is correct |
| 11 |
Correct |
0 ms |
8896 KB |
Output is correct |
| 12 |
Correct |
0 ms |
8896 KB |
Output is correct |
| 13 |
Correct |
0 ms |
8896 KB |
Output is correct |
| 14 |
Correct |
0 ms |
8896 KB |
Output is correct |
| 15 |
Correct |
0 ms |
8896 KB |
Output is correct |
| 16 |
Correct |
0 ms |
8896 KB |
Output is correct |
| 17 |
Correct |
0 ms |
8896 KB |
Output is correct |
| 18 |
Correct |
0 ms |
8896 KB |
Output is correct |
| 19 |
Correct |
0 ms |
8896 KB |
Output is correct |
| 20 |
Correct |
0 ms |
8896 KB |
Output is correct |
| 21 |
Correct |
0 ms |
8896 KB |
Output is correct |
| 22 |
Correct |
0 ms |
8896 KB |
Output is correct |
| 23 |
Correct |
0 ms |
8896 KB |
Output is correct |
| 24 |
Correct |
0 ms |
8896 KB |
Output is correct |
| 25 |
Correct |
0 ms |
8896 KB |
Output is correct |
| 26 |
Correct |
0 ms |
8896 KB |
Output is correct |
| 27 |
Correct |
0 ms |
8896 KB |
Output is correct |
| 28 |
Correct |
0 ms |
8896 KB |
Output is correct |
| 29 |
Correct |
0 ms |
8896 KB |
Output is correct |
| 30 |
Correct |
0 ms |
8896 KB |
Output is correct |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
327 ms |
8896 KB |
Output is correct |
| 2 |
Correct |
115 ms |
8896 KB |
Output is correct |
| 3 |
Correct |
45 ms |
8896 KB |
Output is correct |
| 4 |
Correct |
31 ms |
8896 KB |
Output is correct |
| 5 |
Correct |
45 ms |
8896 KB |
Output is correct |
| 6 |
Correct |
40 ms |
8896 KB |
Output is correct |
| 7 |
Correct |
259 ms |
8896 KB |
Output is correct |
| 8 |
Correct |
159 ms |
8896 KB |
Output is correct |
| 9 |
Correct |
55 ms |
8896 KB |
Output is correct |
| 10 |
Correct |
10 ms |
8896 KB |
Output is correct |
| 11 |
Correct |
109 ms |
8896 KB |
Output is correct |
| 12 |
Correct |
15 ms |
8896 KB |
Output is correct |
| 13 |
Correct |
59 ms |
8896 KB |
Output is correct |
| 14 |
Correct |
231 ms |
8896 KB |
Output is correct |
| 15 |
Correct |
131 ms |
8896 KB |
Output is correct |
| 16 |
Correct |
208 ms |
8896 KB |
Output is correct |
| 17 |
Correct |
95 ms |
8896 KB |
Output is correct |
| 18 |
Correct |
94 ms |
8896 KB |
Output is correct |
| 19 |
Correct |
25 ms |
8896 KB |
Output is correct |
| 20 |
Correct |
124 ms |
8896 KB |
Output is correct |
| 21 |
Correct |
74 ms |
8896 KB |
Output is correct |
| 22 |
Correct |
200 ms |
8896 KB |
Output is correct |
| 23 |
Correct |
80 ms |
8896 KB |
Output is correct |
| 24 |
Correct |
35 ms |
8896 KB |
Output is correct |
| 25 |
Correct |
51 ms |
8896 KB |
Output is correct |
| 26 |
Correct |
136 ms |
8896 KB |
Output is correct |
| 27 |
Correct |
16 ms |
8896 KB |
Output is correct |
| 28 |
Correct |
18 ms |
8896 KB |
Output is correct |
| 29 |
Correct |
367 ms |
8896 KB |
Output is correct |
| 30 |
Correct |
367 ms |
8896 KB |
Output is correct |
