UVALive 7509 Dome and Steles

三分

 #include<bits/stdc++.h>
 using namespace std;
 #define rep(i,a,b) for(int i=a;i<=b;++i)
 #define ms(arr,a) memset(arr,a,sizeof arr)
 const double eps=1e-;
 const int maxn=1e5+;
 int N;
 double r[maxn];
 double calc(double o)
 {
     double odd=min(1.0-o,o),even=max(1.0-o,o);
         double R=even*even+r[N];
         rep(i,,N-)
         {
             if(i&)
             {
                 odd++;
                 R=max(R,odd*odd+r[N-i]);
             }
             else
             {
                 even++;
                 R=max(R,even*even+r[N-i]);
             }
         }
     return sqrt(R);
 }
 double solve(double l,double r)
 {
     double mid,mmid;
     while(l<r)
     {
         mid=(l+r)/2.0;
         mmid=(mid+r)/2.0;
         if(calc(mmid)<calc(mid))
             l=mid+eps;
         else r=mmid-eps;
     }
     return calc(l);
 }
 int main()
 {
     int T;
     scanf("%d",&T);
     for(int Case=;Case<=T;Case++)
     {
         scanf("%d",&N);
         rep(i,,N)
         {
             double a,b;
             scanf("%lf%lf",&a,&b);
             double Max,Min;
             Max=max(a,b);
             Min=min(a,b);
             r[i]=(Max/2.0)*(Max/2.0)+Min*Min;
         }
         sort(r+,r+N+);
         printf("Case #%d: %.10f\n",Case,solve(,));
     }
 }