hdu4717The Moving Points(三分）

 1 #include <iostream>
 2 #include<cstdio>
 3 #include<cstring>
 4 #include<algorithm>
 5 #include<stdlib.h>
 6 #include<vector>
 7 #include<cmath>
 8 #include<queue>
 9 #include<set>
10 using namespace std;
11 #define N 310
12 #define LL long long
13 #define INF 1e8
14 const double eps = 1e-5;
15 const double pi = acos(-1.0);
16 const double inf = ~0u>>2;
17 struct point
18 {
19     double x,y;
20     double vx,vy;
21 }p[N],pp[N];
22 int n;
23 double dis(point a,point b)
24 {
25     return sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));
26 }
27 double calc(double tt)
28 {
29     int i,j;
30     for(i = 1 ; i <= n; i++)
31     {
32         pp[i].x=p[i].x+tt*p[i].vx;
33         pp[i].y=p[i].y+tt*p[i].vy;
34     }
35     double ans = 0.0;
36     for(i = 1 ; i <= n; i++)
37     {
38         for(j = 1 ; j <= n ;j++)
39         ans = max(ans,dis(pp[i],pp[j]));
40     }
41     return ans;
42 }
43 void solve(int k)
44 {
45     double M,RM;
46     double L = 0.0;
47     double R = INF;
48     while (L + eps < R)
49     {
50         M = (L + R) / 2;
51         RM = (M + R) / 2;
52         double s1 = calc(M);
53         double s2 = calc(RM);
54         if ( s1 < s2 ) R = RM;
55         else L = M;
56     }
57     printf("Case #%d: ",k);
58     printf("%.2f %.2f\n",R,calc(R));
59 }
60 int main()
61 {
62     int t,i;
63     int kk = 0;
64     cin>>t;
65     while(t--)
66     {
67         scanf("%d",&n);
68         for(i = 1; i <= n ;i++)
69         scanf("%lf%lf%lf%lf",&p[i].x,&p[i].y,&p[i].vx,&p[i].vy);
70         if(n==1)
71         {
72             printf("0.00 0.00\n");
73             continue;
74         }
75         solve(++kk);
76     }
77     return 0;
78 }