답안 #19255

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
19255	2016-02-23T04:47:35 Z	kaTkaHr	순열 (kriii4_T)	C++14	8 / 100	2000 ms	1084 KB

T

#include <stdio.h>
#include<vector>
#include <algorithm>
#include <map>

using namespace std;

typedef long long ll;

const int MX = 105, MM = 1000000007;

ll rv(ll A){
    ll R = 1, B = MM-2;
    while(B){
        if( B&1 ) R = R * A % MM;
        A = A * A % MM; B /= 2;
    }
    return R;
}

struct frac{
    ll A, B;
		frac(ll A):A(A), B(1){}
    frac(ll a, ll b){
        A = (a%MM+MM) % MM;
        B = (b%MM+MM) % MM;
    }
    frac(){A = 0, B = 1;}
    frac operator+ (const frac &l)const{
        return frac((A * l.B + B * l.A) % MM, B * l.B % MM);
    }
    frac operator*(const frac &l)const{
        return frac(A*l.A % MM, B*l.B % MM);
    }
    frac operator/(const frac &l)const{
        return frac(A*l.B % MM, B*l.A % MM);
    }
    frac operator- (const frac &l)const{
        return frac((A*l.B - B*l.A%MM + MM) % MM, B*l.B % MM);
    }
    ll v(){ return A * rv(B) % MM; }
};

int main()
{
	int N, KK;
	scanf("%d%d", &N, &KK); 
	frac tot = 0;
	for(int K = KK+1; K <= N; K++){
		frac ans = 0, mul = 1;
		for(int i = 1; i <= N; i++){
			mul = mul * i;
		}
		for(int i = N; i >= 1; i--){
			mul = mul / i;
			ans = ans + mul * (N-i+1);
			mul = mul * (i-K);
		}
		ans = ans * K * (N-K+1);
		tot = ans + tot;
	}
	printf("%lld\n", tot.v());
}

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	5 ms	1084 KB	Output is correct
17	Correct	28 ms	1084 KB	Output is correct
18	Correct	9 ms	1084 KB	Output is correct
19	Correct	18 ms	1084 KB	Output is correct
20	Correct	23 ms	1084 KB	Output is correct
21	Correct	32 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	39 ms	1084 KB	Output is correct
25	Correct	5 ms	1084 KB	Output is correct
26	Correct	47 ms	1084 KB	Output is correct
27	Correct	0 ms	1084 KB	Output is correct
28	Correct	89 ms	1084 KB	Output is correct
29	Correct	87 ms	1084 KB	Output is correct
30	Correct	32 ms	1084 KB	Output is correct

Subtask #2

0.0 / 92.0

#	결과	실행 시간	메모리	Grader output
1	Execution timed out	2000 ms	1080 KB	Program timed out
2	Halted	0 ms	0 KB	-