10056 - What is the Probability ?

/*
简单概率题，一次AC
*/
#include <cstdio>
int main()
{
//freopen("f://data.in", "r", stdin);
int T;
scanf("%d", &T);
while(T--)
{
int N, I;
double p;
scanf("%d %lf %d", &N, &p, &I);
double q, t;
int i;
for(i = 0, t = 1; i < N; ++ i)
t *= (1 - p);
for(q = p, i = 1; i < I; ++ i)
q *= (1 - p);
double ans = q;
while(q > 1e-6)
{
q *= t;
ans += q;
}
printf("%.4lf\n", ans);
}
return 0;
}