hdu 4717 The Moving Points(三分)

 1 #include<bits/stdc++.h>
 2 #define F(i,a,b) for(int i=a;i<=b;++i)
 3 using namespace std;
 4 
 5 const int N=307;
 6 int t,n,cas;
 7 double X[N],Y[N],VX[N],VY[N];
 8 
 9 double dis(double a,double b,double c,double d){return sqrt((c-a)*(c-a)+(d-b)*(d-b));}
10 
11 double check(double time)
12 {
13     double mx=0;
14     F(i,1,n)F(j,1,n)
15     mx=max(mx,dis(X[i]+time*VX[i],Y[i]+time*VY[i],X[j]+time*VX[j],Y[j]+time*VY[j]));
16     return mx;
17 }
18 
19 int main(){
20     scanf("%d",&t);
21     while(t--)
22     {
23         scanf("%d",&n);
24         F(i,1,n)scanf("%lf%lf%lf%lf",X+i,Y+i,VX+i,VY+i);
25         double l=0,r=1e7,mid,mmid;
26         F(i,1,100)
27         {
28             mid=(l+r)/2,mmid=(mid+r)/2;
29             if(check(mid)<check(mmid))r=mmid;else l=mid;
30         }
31         printf("Case #%d: ",++cas);
32         check(l)>check(r)?printf("%.2f %.2f\n",l,check(l)):printf("%.2f %.2f\n",r,check(r));
33     }
34     return 0;
35 }