uva 10056

概率 Q += p*pow(1-p, i*n+k-1） i = 0,1,2,3......

#include <cstdio>
#include <cmath>

int main ()
{
    int t;
    scanf("%d",&t);
    while(t--)
    {
        int n,k;
        double p;
        scanf("%d%lf%d",&n,&p,&k);
        double ans = p*pow(1-p, k-1), cc = 0;
        int i = 1;
        while(ans - cc > 1e-9)
        {
            cc = ans;
            ans += p*pow(1-p, n*i+k-1);
            i++;
        }
        printf("%.4lf\n",ans);
    }
    return 0;
}