hdu 1007 Quoit Design

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <cmath>
 5 #include <algorithm>
 6 using namespace std;
 7 #define INF 0x7f7f7f
 8 int n;
 9 struct Point
10 {
11     double x,y;
12 }p[100001];
13 bool cmp(Point a,Point b)
14 {
15     if(a.x==b.x)
16     {
17         return a.y<b.y;
18     }
19     return a.x<b.x;
20 }
21 double dis(Point a,Point b)
22 {
23     return sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));
24 }
25 double getMin(int i)
26 {
27      double d=999999,di=0;
28      for(int j=i+1;j<n;j++)
29      {
30          di=dis(p[i],p[j]);
31          if(d>di)d=di;
32          else break;
33      }
34      return d;
35 }
36 int main()
37 {
38     int i,j,k;
39     double ans,f;
40     while(scanf("%d",&n)!=EOF)
41     {
42         if(!n)break;
43         for(i=0;i<n;i++)
44         {
45             scanf("%lf%lf",&p[i].x,&p[i].y);
46         }
47         sort(p,p+n,cmp);
48         ans=INF;
49         for(i=0;i<n-1;i++)
50         {
51             f=getMin(i);
52             if(ans>f)ans=f;
53         }
54         printf("%.2lf\n",ans/2.0);
55     }
56     return 0;
57 }