oj.uz

답안 #19330

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
19330 2016-02-24T09:49:59 Z imsifile Ω (kriii4_P3) C++
0 / 100
 0 ms 1084 KB 
#include<stdio.h>
#define mod 1000000007

typedef long long lld;
lld a, b, sum;

lld exp(lld a, lld b){
	if(b==0)return 1;
	lld k=exp(a, b/2);
	k=(k*k)%mod;
	if(b%2)k=(k*a)%mod;
	return k;
}

int n, k;
lld p, q, pq, npq, dy[111], re;

int main(){
	int n, i;
	scanf("%lld%lld%d%d", &p, &q, &n, &k);
	pq = q*exp(p,mod-2)%mod, npq = p*exp(p-q,mod-2)%mod;
	dy[1]=1;
	for(i=1; i<n; i++)dy[i+1] = (dy[i] - pq*dy[i-1]%mod + mod)*npq%mod;
	re = exp(dy[n],mod-2);
	printf("%lld", dy[k]*re%mod);
	return 0;
}

Subtask #1
0.0 / 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 Incorrect 0 ms 1084 KB Output isn't correct
5 Halted 0 ms 0 KB -