poj 3122 pie(二分搜索)

#include <iostream>#include <cmath>using namespace std;const double PI=acos(-1.0); //3.14过不了 double area[10005];double max_area;int n,f;int OK(double k){int i,Count=0;for(i=0;i<n;i++)Count+=floor(area[i]/k);return Count>=f+1;}double binary(){double left=0,right=max_area,middle;while(left<right&&(right-left)>=10e-6){middle=(left+right)/2;if(!OK(middle)) right=middle;else left=middle;}return middle;}int main(int argc, char *argv[]){int t,i,j;double r;cin>>t;while(t--){cin>>n>>f;for(max_area=-1,i=0;i<n;i++){cin>>r; area[i]=PI*r*r; max_area=max(max_area,area[i]); }printf("%.4lf\n",binary());} return 0;}