poj3122Pie

http://poj.org/problem?id=3122

#include <iostream>
#include<cstdio>
#include<cstring>
#include<stdlib.h>
#include<cmath>
#define eps 1e-8
#define pi 3.14159265359//精度高一点 6位错了一次
using namespace std;
int main()
{
    int i,j,n,f,t;
    double r[10005];
    cin>>t;
    while(t--)
    {
        cin>>n>>f;
        double low=0.0,high = 0.0;
        for(i = 1; i <= n ; i++)
        {
            cin>>r[i];
            if((r[i]*r[i])>high)
                high = r[i]*r[i];
        }
        double mid = (low+high)/2;
        while(low+eps<high)
        {
            int k = 0 ;
            for(i = 1 ; i <= n ; i++)
            {
                k+=(int)((r[i]*r[i])/mid);
            }
            if(k>=(f+1))
                low = mid ;
            else
                high = mid;
            mid = (low+high)/2;
        }
        printf("%.4lf\n",pi*mid+eps);
    }
    return 0;
}