답안 #21288

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
21288	2017-04-12T12:40:55 Z	gs14004	능력 (kriii4_S)	C++11	10 / 100	2000 ms	393544 KB

S

#include <bits/stdc++.h>
using namespace std;
typedef long long lint;
typedef long double llf;
typedef pair<int, int> pi;
const int mod = 1e9 + 7;

lint ipow(lint x, lint p){
	lint ret = 1, piv = x % mod;
	while(p){
		if(p&1) ret *= piv;
		piv *= piv;
		ret %= mod;
		piv %= mod;
		p >>= 1;
	}
	return ret % mod;
}

int n;
lint p[5005], d[5005], fact[5005];
lint d1[5005][5005], d2[5005][5005];

int main(){
	cin >> n;
	lint ans = 0;
	fact[0] = 1;
	for(int i=1; i<=n; i++){
		fact[i] = fact[i-1] * i % mod;
		cin >> p[i] >> d[i];
		p[i] *= ipow(1000000000, mod - 2);
		p[i] %= mod;
	}
	d1[0][0] = 1;
	for(int i=1; i<=n; i++){
		for(int j=0; j<=n; j++){
			d1[i][j] = d1[i-1][j];
			if(j > 0) d1[i][j] += d1[i-1][j-1] * (mod + 1 - p[i]);
			d1[i][j] %= mod;
		}
	}
	d2[n+1][0] = 1;
	for(int i=n; i>=1; i--){
		for(int j=0; j<=n; j++){
			d2[i][j] = d2[i+1][j];
			if(j > 0) d2[i][j] += d2[i+1][j-1] * (mod + 1 - p[i]);
			d2[i][j] %= mod;
		}
	}
	lint ret = 0;
	for(int i=1; i<=n; i++){
		lint cur = 0;
		for(int j=0; j<n; j++){
			for(int k=0; k<n; k++){
				lint cp = d1[i-1][j] * d2[i+1][k] % mod;
				cp *= fact[j + k];
				cp %= mod;
				cp *= fact[n - 1 - j - k];
				cp %= mod;
				cur += cp;
				cur %= mod;
			}
		}
		ret += cur * (p[i] * d[i] % mod) % mod;
		ret %= mod;
	}
	ret *= ipow(fact[n], mod - 2);
	ret %= mod;
	cout << ret;
}

Compilation message

S.cpp: In function 'int main()':
S.cpp:26:7: warning: unused variable 'ans' [-Wunused-variable]
  lint ans = 0;
       ^

Subtask #1

10.0 / 10.0

#	결과	실행 시간	메모리	Grader output
1	Correct	89 ms	393544 KB	Output is correct
2	Correct	83 ms	393544 KB	Output is correct
3	Correct	86 ms	393544 KB	Output is correct
4	Correct	86 ms	393544 KB	Output is correct
5	Correct	86 ms	393544 KB	Output is correct
6	Correct	86 ms	393544 KB	Output is correct
7	Correct	79 ms	393544 KB	Output is correct
8	Correct	89 ms	393544 KB	Output is correct
9	Correct	79 ms	393544 KB	Output is correct
10	Correct	83 ms	393544 KB	Output is correct
11	Correct	83 ms	393544 KB	Output is correct
12	Correct	79 ms	393544 KB	Output is correct
13	Correct	76 ms	393544 KB	Output is correct
14	Correct	99 ms	393544 KB	Output is correct
15	Correct	89 ms	393544 KB	Output is correct
16	Correct	56 ms	393544 KB	Output is correct
17	Correct	63 ms	393544 KB	Output is correct
18	Correct	63 ms	393544 KB	Output is correct
19	Correct	86 ms	393544 KB	Output is correct
20	Correct	56 ms	393544 KB	Output is correct

Subtask #2

0 / 90.0

#	결과	실행 시간	메모리	Grader output
1	Execution timed out	2000 ms	393544 KB	Execution timed out
2	Halted	0 ms	0 KB	-