hdu 1162 Eddy's picture（最小生成树）

 1 #include<iostream>
 2 #include<stdio.h>
 3 #include<string.h>
 4 #include<stdlib.h>
 5 #include<math.h>
 6 #include<algorithm>
 7 #define LL long long
 8 #define mod 1e9 + 7
 9 const int M = 105;
10 
11 using namespace std;
12 
13 struct node{
14     int x;
15     int y;
16     double value;
17 }a[M * M >> 1];
18 
19 int cun[M];
20 
21 double dis(double x1, double y1, double x2, double y2)
22 {
23     return sqrt(1.0 * (x1 - x2) * (x1 - x2) + 1.0 * (y1 - y2) * (y1 - y2));
24 }
25 
26 bool cmp(node a, node b)
27 {
28     return a.value < b.value;
29 }
30 
31 int find(int x)
32 {
33     return cun[x] == x ? x : cun[x] = find(cun[x]);
34 }
35 
36 void shu(int x, int y)
37 {
38     int p = find(x);
39     int q = find(y);
40     if(p != q)
41         cun[p] = q;
42 }
43 
44 int main()
45 {
46     int n;
47     double s[M], e[M];
48     while( cin >> n )
49     {
50         int temp = 1;
51         for(int i = 1; i <= n; ++i)
52             cin >> s[i] >> e[i];
53         for(int i = 1; i <= n; ++i)
54             for(int j = i + 1; j <= n; ++j)
55             {
56                 a[temp].x = i;
57                 a[temp].y = j;
58                 a[temp].value = dis(s[i],e[i],s[j],e[j]);
59                 temp++;
60             }
61         for(int i = 0; i <= n; ++i)
62             cun[i] = i;
63         sort(a,a + temp,cmp);
64         double ans = 0;
65         for(int i = 1; i < temp; ++i)
66         {
67             if(find(a[i].x) != find(a[i].y))
68             {
69                 shu(a[i].x,a[i].y);
70                 ans += a[i].value;
71             }
72         }
73         printf("%.2lf\n",ans);
74     }
75     return 0;
76 }