uva 10397【Connect the Campus】

Krustral 变形。。。。。。
代码如下：
 1 #include <cstdio>
 2 #include <cstring>
 3 #include <algorithm>
 4 #include <cmath>
 5 
 6 struct distance
 7 {
 8     int u,v;
 9     double w;
10 }d[1000000];
11 
12 struct point
13 {
14     int x,y;
15 }p[1000];
16 
17 int f[1000];
18 int n;
19 int num;
20 
21 bool cmp(const distance& a,const distance& b)
22 {
23     if(a.w == b.w)
24         return a.u < b.u;
25     return a.w < b.w;
26 }
27 
28 double dis(point a,point b)
29 {
30     return sqrt(1.0*(a.x - b.x) * (a.x - b.x) + 1.0 * (a.y - b.y) * (a.y - b.y));
31 }
32 
33 int find(int x)
34 {
35     if(x == f[x])
36         return x;
37     f[x] = find(f[x]);
38     return f[x];
39 }
40 
41 void Krustral()
42 {
43     double sum = 0;
44     int k = 0;
45     for(int i = 0;i < num;i ++)
46     {
47         int fa = find(d[i].u);
48         int fb = find(d[i].v);
49         if(fa != fb)
50         {
51             f[fa] = fb;
52             sum += d[i].w;
53             k ++;
54         }
55         if(k == n -1)
56             break;
57     }
58 
59     printf("%.2lf\n",sum);
60 }
61 
62 int main()
63 {
64     while(scanf("%d",&n) == 1)
65     {
66         num = 0;
67         for(int i = 1;i <= n;i ++)
68         {
69             scanf("%d%d",&p[i].x,&p[i].y);
70             for(int j = 1;j < i;j ++)
71             {
72                 d[num].u = i;
73                 d[num].v = j;
74 
75                 d[num ++].w = dis(p[i],p[j]);
76             }
77         }
78 
79         std::sort(d,d + num,cmp);
80         for(int i = 0;i <= n;i ++)
81         {
82             f[i] =i;
83         }
84         int on;
85         scanf("%d",&on);
86         for(int i = 0;i < on;i ++)
87         {
88             int a,b;
89             scanf("%d%d",&a,&b);
90             f[find(a)] = find(b);
91         }
92 
93         Krustral();
94     }
95     return 0;
96 }