답안 #19916

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
19916	2016-02-25T07:04:46 Z	xdoju	순열 (kriii4_T)	C++14	100 / 100	845 ms	1084 KB

T

#include <stdio.h>

const int MOD = 1000000007;

int mul(int x, int y){ return (long long)x * y % MOD; }

int power(int x, int y){
  if(y == 0) return 1;

  int r = power(x, y / 2);
  r = mul(r, r);
  if(y % 2 == 1) r = mul(r, x);
  return r;
}

int modinv(int x){
  return power(x, MOD - 2);
}

int main(){
  int N, K; scanf("%d%d", &N, &K);

  int v = 1;
  for(int i = 1; i <= N + 1; i++) v = mul(v, i); // fac(N + 1)

  v = mul(v, N + 1);

  int ans = 0;

  for(int k = 1; k <= N; k++){
    v = mul(v, k);
    v = mul(v, modinv(k + 1));
    v = mul(v, N - k + 1);
    v = mul(v, modinv(N - k + 2));

    if(k >= K + 1) ans = (ans + v) % MOD;
  }

  printf("%d\n", ans);
  return 0;
}

Subtask #1

8.0 / 8.0

#	결과	실행 시간	메모리	Grader output
1	Correct	0 ms	1084 KB	Output is correct
2	Correct	0 ms	1084 KB	Output is correct
3	Correct	0 ms	1084 KB	Output is correct
4	Correct	0 ms	1084 KB	Output is correct
5	Correct	0 ms	1084 KB	Output is correct
6	Correct	0 ms	1084 KB	Output is correct
7	Correct	0 ms	1084 KB	Output is correct
8	Correct	0 ms	1084 KB	Output is correct
9	Correct	0 ms	1084 KB	Output is correct
10	Correct	0 ms	1084 KB	Output is correct
11	Correct	0 ms	1084 KB	Output is correct
12	Correct	0 ms	1084 KB	Output is correct
13	Correct	0 ms	1084 KB	Output is correct
14	Correct	0 ms	1084 KB	Output is correct
15	Correct	0 ms	1084 KB	Output is correct
16	Correct	0 ms	1084 KB	Output is correct
17	Correct	0 ms	1084 KB	Output is correct
18	Correct	0 ms	1084 KB	Output is correct
19	Correct	0 ms	1084 KB	Output is correct
20	Correct	0 ms	1084 KB	Output is correct
21	Correct	0 ms	1084 KB	Output is correct
22	Correct	0 ms	1084 KB	Output is correct
23	Correct	0 ms	1084 KB	Output is correct
24	Correct	0 ms	1084 KB	Output is correct
25	Correct	0 ms	1084 KB	Output is correct
26	Correct	0 ms	1084 KB	Output is correct
27	Correct	0 ms	1084 KB	Output is correct
28	Correct	0 ms	1084 KB	Output is correct
29	Correct	0 ms	1084 KB	Output is correct
30	Correct	1 ms	1084 KB	Output is correct

Subtask #2

92.0 / 92.0

#	결과	실행 시간	메모리	Grader output
1	Correct	843 ms	1084 KB	Output is correct
2	Correct	703 ms	1084 KB	Output is correct
3	Correct	714 ms	1084 KB	Output is correct
4	Correct	154 ms	1084 KB	Output is correct
5	Correct	161 ms	1084 KB	Output is correct
6	Correct	714 ms	1084 KB	Output is correct
7	Correct	779 ms	1084 KB	Output is correct
8	Correct	439 ms	1084 KB	Output is correct
9	Correct	201 ms	1084 KB	Output is correct
10	Correct	89 ms	1084 KB	Output is correct
11	Correct	260 ms	1084 KB	Output is correct
12	Correct	538 ms	1084 KB	Output is correct
13	Correct	678 ms	1084 KB	Output is correct
14	Correct	838 ms	1084 KB	Output is correct
15	Correct	484 ms	1084 KB	Output is correct
16	Correct	503 ms	1084 KB	Output is correct
17	Correct	543 ms	1084 KB	Output is correct
18	Correct	318 ms	1084 KB	Output is correct
19	Correct	294 ms	1084 KB	Output is correct
20	Correct	659 ms	1084 KB	Output is correct
21	Correct	219 ms	1084 KB	Output is correct
22	Correct	686 ms	1084 KB	Output is correct
23	Correct	573 ms	1084 KB	Output is correct
24	Correct	140 ms	1084 KB	Output is correct
25	Correct	734 ms	1084 KB	Output is correct
26	Correct	463 ms	1084 KB	Output is correct
27	Correct	214 ms	1084 KB	Output is correct
28	Correct	841 ms	1084 KB	Output is correct
29	Correct	845 ms	1084 KB	Output is correct
30	Correct	840 ms	1084 KB	Output is correct