Uva10034(Freckles)

最基础的最小生成树，简单题。

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 1 #include <stdio.h>
 2 #include <math.h>
 3 #include <stdlib.h>
 4 #define D(x1,y1,x2,y2) (sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2)))
 5 #define N 100
 6 #define M 5000
 7 struct node
 8 {
 9     int a,b;
10     double d;
11 }edge[M];
12 int n,m;
13 double x[N],y[N];
14 int p[M];
15 void make_set()
16 {
17     int i;
18     for(i=0;i<m;i++)  p[i]=i;
19 }
20 int find_set(int i)
21 {
22     return i==p[i]?p[i]:(p[i]=find_set(p[i]));
23 }
24 int union_set(int i,int j)
25 {
26     i=p[i],j=p[j];
27     p[j]=i;
28 }
29 int cmp(void const *a,void const *b)
30 {
31     return ((struct node*)a)->d-((struct node*)b)->d>0?1:-1;
32 }
33 int main()
34 {
35     int t,i,j;
36     double ans;
37     scanf("%d",&t);
38     while(t--)
39     {
40         scanf("%d",&n);
41         for(i=0;i<n;i++)
42         {
43             scanf("%lf%lf",&x[i],&y[i]);
44         }
45         m=0;
46         for(i=0;i<n;i++)
47         {
48             for(j=i+1;j<n;j++)
49             {
50                 edge[m].a=i,edge[m].b=j;
51                 edge[m++].d=D(x[i],y[i],x[j],y[j]);
52             }
53         }
54         make_set();
55         qsort(edge,m,sizeof(edge[0]),cmp);
56         for(i=0,ans=0;i<m;i++)
57         {
58             if(find_set(edge[i].a)==find_set(edge[i].b))    continue;
59             union_set(edge[i].a,edge[i].b);
60             ans+=edge[i].d;
61         }
62         printf("%.2lf\n",ans);
63         if(t)   printf("\n");
64     }
65     return 0;
66 }

 

posted @ 2012-04-12 22:59  BeatLJ  阅读(281)  评论(0)  编辑  收藏  举报