oj.uz

답안 #19205

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
19205 2016-02-20T15:37:42 Z kriii Ω (kriii4_P3) C++14
100 / 100
 0 ms 1084 KB 
#include <stdio.h>

const long long mod = 1000000007;

long long fpow(long long a, long long p)
{
	a = (a % mod + mod) % mod;
	p = (p % (mod - 1) + mod - 1) % (mod - 1);
	long long r = 1;
	while (p){
		if (p & 1) r = r * a % mod;
		a = a * a % mod;
		p >>= 1;
	}
	return r;
}

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

	if (K == 0) puts("0");
	else if (K == N) puts("1");
	else if (Q == 0) puts("1");
	else if (Q == P) puts("0");
	else{
		long long v[101];
		long long pr = Q * fpow(P,-1) % mod, rv = fpow(1-pr,-1);
		v[0] = 0; v[1] = 1;
		for (int i=2;i<=N;i++) v[i] = ((v[i-1] - pr * v[i-2]) % mod * rv % mod + mod) % mod;
		printf ("%lld\n",v[K]*fpow(v[N],-1)%mod);
	}

	return 0;
}

Subtask #1
100.0 / 100.0

# 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 0 ms 1084 KB Output is correct