UVA 557(p344)----Burger

#include<iostream>
#include<cstdio>
using namespace std;
const int maxn=1e5;
double p[maxn+50];
int n;
void prepare()
{
    p[1]=1.0;
    for(int i=1;i<=maxn;i++)
        p[i+1]=(double)(2*i-1)/(double)(2*i)*p[i];
}
int main()
{
    prepare();
    scanf("%d",&n);
    for(int i=0;i<n;i++)
    {
        int x;
        scanf("%d",&x);
        printf("%.4lf\n",1-p[x/2]);
    }
    return 0;
}

题目地址：https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&problem=498