BZOJ2318: Spoj4060 game with probability Problem

#include<iostream>
#include<algorithm>
#include<cstring>
#include<cstdio>
#include<cmath>
#define N 1005
using namespace std;
int T,n;
double p,q,f[N],g[N];
int main()
{
    scanf("%d",&T);
    while (T--)
    {
        scanf("%d",&n); n=min(n,1000);
        scanf("%lf%lf",&p,&q);
        f[0]=0; g[0]=1;
        for (int i=1; i<=n; i++)
        {
            if (f[i-1]>g[i-1]) p=1-p,q=1-q;
            f[i]=(1.0*p*g[i-1]+1.0*(1-p)*q*f[i-1])/(1.0-1.0*(1-p)*(1-q));
            g[i]=(1.0*q*f[i-1]+1.0*(1-q)*p*g[i-1])/(1.0-1.0*(1-p)*(1-q));
            if(f[i-1]>g[i-1])p=1-p,q=1-q;
        }
        printf("%0.6lf\n",f[n]);
    }
    return 0;
}

View Code