poj 3122 Pie 夜

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

#include<iostream>
#include<string>
#include<cstring>
#include<cmath>
#include<cstdio>
#include<algorithm>
using namespace std;
const double K=1e-4;
const double PI=acos(-1);
const int N=10005;
double size[N];
int n,F;
bool toosmall(double k)
{
    int sum=0;
    for(int i=0;i<=n;++i)
    {
        sum+=(int)(size[i]/k);
    }
    if(sum>=(F+1))
    return true;
    return false;
}
int main()
{
    int T;
    cin>>T;
    while(T--)
    {
        cin>>n>>F;
        double Max=0;
        double sum=0;
        for(int i=1;i<=n;++i)
        {
            int k;
            cin>>k;
            size[i]=k*k*PI;
            sum+=size[i];
            if(size[i]>Max)
            Max=size[i];
            //cout<<size[i]<<" ";
        }
        double high=(sum)/(F+1);
        double low=(Max)/(F+1);
        double mid=(high+low)/2;
        while(high-low>K)
        {
            if(toosmall(mid))
            {
                low=mid;
            }
            else
            {
                high=mid;
            }
            mid=(high+low)/2;
        }
        printf("%.3f\n",mid);
    }
    return 0;
}