hdu 1162 Eddy's picture (prim)

 1 #include <cmath>
 2 #include <cstdio>
 3 #include <climits>
 4 #include <algorithm>
 5 using namespace std;
 6 
 7 int n;
 8 double my_map[110][110];
 9 
10 struct node
11 {
12     double a, b;
13 }P[110];
14 
15 double my_prim()
16 {
17     int my_pos = 1, my_book[110] = {0, 1};
18     double my_ans = 0.0, my_dis[110] = {0, INT_MAX};
19     for (int i = 2; i <= n; ++ i)
20         my_dis[i] = my_map[i][my_pos];
21 
22     for (int i = 1; i < n; ++ i)
23     {
24         double my_temp = INT_MAX;
25         for (int j = 1; j <= n; ++ j)
26         {
27             if (!my_book[j] && my_dis[j] < my_temp)
28             {
29                 my_temp = my_dis[j];
30                 my_pos = j;
31             }
32         }
33         my_ans += my_temp;
34         my_book[my_pos] = 1;
35         for (int j = 1; j <= n; ++ j)
36         {
37             if (!my_book[j] && my_dis[j] > my_map[j][my_pos])
38                 my_dis[j] = my_map[j][my_pos];
39         }
40     }
41     return my_ans;
42 }
43 
44 int main()
45 {
46     /**
47         Date Input Initialize
48     */
49     while (~scanf("%d", &n))
50     {
51         for (int i = 1; i <= n; ++ i)
52             scanf("%lf%lf", &P[i].a, &P[i].b);
53         for (int i = 1; i <= n; ++ i)
54         {
55             for (int j = i+1; j <= n; ++ j)
56             {
57                 double my_temp_a = (P[i].a - P[j].a) * (P[i].a - P[j].a);
58                 double my_temp_b = (P[i].b - P[j].b) * (P[i].b - P[j].b);
59                 double my_temp = sqrt(my_temp_a + my_temp_b);
60                 my_map[i][j] = my_map[j][i] = my_temp;
61             }
62         }
63         printf("%.2lf\n", my_prim());
64     }
65     return 0;
66 }