#include<stdio.h>
int mod=1000000007;
int p,q,n,m;
int a[110];
int b[110];
long long int f(long long int x,long long int y){
if(y==0)return 1;
long long int r=f(x,y/2);
r*=r;
r%=mod;
if(y%2==0)return r;
r*=x;
r%=mod;
return r;
}
int main(){
int i;
long long int res=0;
scanf("%d%d%d%d",&p,&q,&n,&m);
p=(p-q)*f(p,mod-2)%mod;
b[1]=p;
for(i=1;i<n;i++){
b[i+1]=p*f(((long long int)b[i]*((p+mod-1)%mod)%mod+1)%mod,mod-2)%mod;
}
a[n]=1;
for(i=n-1;i>0;i--){
a[i]=(long long int)a[i+1]*b[i]%mod;
}
a[0]=0;
printf("%d\n",a[m]);
}
# |
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 |