답안 #19495

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
19495	2016-02-24T14:14:32 Z	kaTkaHr	악수 (kriii4_D)	C++14	100 / 100	2942 ms	34544 KB

D

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

using namespace std;

typedef long long ll;

const int MX = 45, MM = 1000000007;

template<typename T>
T pw(T A, ll B){
  T R = 1;
  while(B){
    if( B&1 ) R = R * A;
    A = A * A; B /= 2;
  }
  return R;
}

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

frac D[MX][MX*MX], E[MX][MX*MX], C[MX*MX][MX*MX];

int main()
{
	int N, T;
	scanf("%d", &N); T = N*(N-1) / 2;

	C[0][0] = 1;
	for(int i = 1; i <= T || i <= N; i++){
		C[i][0] = 1;
		for(int j = 1; j <= i; j++){
			C[i][j] = C[i-1][j-1] + C[i-1][j];
		}
	}

	D[1][0] = E[1][0] = 1;
	for(int i = 2; i <= N; i++){
		for(int x = i-1; x <= i*(i-1)/2; x++){
			for(int k = 1; k <= i-1; k++){
				frac t = 0;
				for(int l = 0; l <= x-1; l++){
					t = t + D[k][l] * D[i-k][x-l-1] * C[x-1][l];
				}
				E[i][x] = E[i][x] + t * C[i-1][k-1] * frac(k*(i-k),1);
			}
			D[i][x] = D[i][x-1] * frac(i*(i-1)/2 - x + 1, 1) + E[i][x];
		}
	}
	frac ans = 0, mul = 1;
	frac tot = 0;
	for(int i = 0; i <= T; i++){
		tot = tot + E[N][i] * mul;
		ans = ans + E[N][i] * i * mul;
		mul = mul * frac(1, T-i);
	}
	printf("%lld\n", ans.v());
}

Subtask #1

5.0 / 5.0

#	결과	실행 시간	메모리	Grader output
1	Correct	4 ms	34544 KB	Output is correct
2	Correct	0 ms	34544 KB	Output is correct
3	Correct	8 ms	34544 KB	Output is correct
4	Correct	4 ms	34544 KB	Output is correct
5	Correct	0 ms	34544 KB	Output is correct

Subtask #2

95.0 / 95.0

#	결과	실행 시간	메모리	Grader output
1	Correct	0 ms	34544 KB	Output is correct
2	Correct	0 ms	34544 KB	Output is correct
3	Correct	4 ms	34544 KB	Output is correct
4	Correct	0 ms	34544 KB	Output is correct
5	Correct	4 ms	34544 KB	Output is correct
6	Correct	5 ms	34544 KB	Output is correct
7	Correct	0 ms	34544 KB	Output is correct
8	Correct	3 ms	34544 KB	Output is correct
9	Correct	6 ms	34544 KB	Output is correct
10	Correct	10 ms	34544 KB	Output is correct
11	Correct	16 ms	34544 KB	Output is correct
12	Correct	18 ms	34544 KB	Output is correct
13	Correct	25 ms	34544 KB	Output is correct
14	Correct	42 ms	34544 KB	Output is correct
15	Correct	46 ms	34544 KB	Output is correct
16	Correct	65 ms	34544 KB	Output is correct
17	Correct	89 ms	34544 KB	Output is correct
18	Correct	106 ms	34544 KB	Output is correct
19	Correct	139 ms	34544 KB	Output is correct
20	Correct	176 ms	34544 KB	Output is correct
21	Correct	227 ms	34544 KB	Output is correct
22	Correct	278 ms	34544 KB	Output is correct
23	Correct	349 ms	34544 KB	Output is correct
24	Correct	427 ms	34544 KB	Output is correct
25	Correct	523 ms	34544 KB	Output is correct
26	Correct	637 ms	34544 KB	Output is correct
27	Correct	778 ms	34544 KB	Output is correct
28	Correct	927 ms	34544 KB	Output is correct
29	Correct	1113 ms	34544 KB	Output is correct
30	Correct	1323 ms	34544 KB	Output is correct
31	Correct	1564 ms	34544 KB	Output is correct
32	Correct	1845 ms	34544 KB	Output is correct
33	Correct	2166 ms	34544 KB	Output is correct
34	Correct	2531 ms	34544 KB	Output is correct
35	Correct	2942 ms	34544 KB	Output is correct