poj Pie
http://poj.org/problem?id=3122
1 #include<cstdio> 2 #include<cstring> 3 #include<cmath> 4 #define maxn 10010 5 #include<algorithm> 6 using namespace std; 7 8 const double pi=acos(-1.0); 9 const double eps=1e-8; 10 double r[maxn]; 11 int n,f; 12 13 int main() 14 { 15 int t; 16 scanf("%d",&t); 17 while(t--){ 18 double max1=0; 19 scanf("%d%d",&n,&f); 20 f++; 21 for(int i=0; i<n; i++) 22 { 23 scanf("%lf",&r[i]); 24 r[i]*=r[i]; 25 if(max1<r[i]) 26 max1=r[i]; 27 } 28 double low=0,high=max1,mid; 29 while(high-low>eps) 30 { 31 mid=(high+low)/2; 32 int ans=0; 33 for(int i=0; i<n; i++) 34 ans+=(int)(r[i]/mid); 35 if(ans<f) 36 high=mid; 37 else 38 low=mid; 39 } 40 printf("%.4lf\n",pi*mid); 41 } 42 return 0; 43 }
