【HDU1875】畅通工程再续（MST基础题）

 1 #include <iostream>
 2 #include <cstring>
 3 #include <cstdio>
 4 #include <cstdio>
 5 #include <cctype>
 6 #include <cmath>
 7 #include <algorithm>
 8 #include <numeric>
 9 
10 #define typec double
11 using namespace std;
12 
13 const typec inf = 0xffff;
14 const int V = 1005;
15 int vis[V];
16 typec lowc[V], Map[V][V], point[V][2];
17 
18 typec prim (typec cost[][V], int n) {
19     int i, j, p;
20     typec minc, res = 0;
21     memset(vis, 0, sizeof(vis));
22     vis[0] = 1;
23     for (i = 1; i < n; ++ i) lowc[i] = cost[0][i];
24     for (i = 1; i < n; ++ i) {
25         minc = inf; p = -1;
26         for (j = 0; j < n; ++ j ) {
27             if (0 == vis[j] && minc > lowc[j]) {
28                 minc = lowc[j];
29                 p = j;
30             }
31         }
32         if (inf == minc) return -1;
33         res += minc;
34         vis[p] = 1;
35         for (j = 0; j < n; ++ j) {
36             if (0 == vis[j] && lowc[j] > cost[p][j]) {
37                 lowc[j] = cost[p][j];
38             }
39         }
40     }
41     return res;
42 }
43 
44 double cal_dis (double x1, double y1, double x2, double y2) {
45     return sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));
46 }
47 
48 int main () {
49     int T; scanf("%d", &T);
50     while (T --) {
51         //vector<pair<double, double> > p;
52         int n; scanf("%d", &n);
53         for (int i = 0; i < n; ++ i) {
54             scanf("%lf%lf", &point[i][0], &point[i][1]);
55         }
56 
57         for (int i = 0 ; i < 105; ++ i) {
58             for (int j = 0; j < 105; ++ j) {
59                 if (i == j) Map[i][j] = 0;
60                 else Map[i][j] = inf;
61             }
62         }
63 
64         for (int i = 0; i < n; ++i) {
65             for (int j = i + 1; j < n; ++ j) {
66                 double w = cal_dis(point[i][0], point[i][1],point[j][0],point[j][1]);
67                 if (w >= 10 && w <= 1000)
68                     Map[i][j] = Map[j][i] = min(Map[i][j], w);
69                 else continue;
70                 /*cout << Map[i][j] << endl;
71                 cout << Map[j][i] << endl;*/
72             }
73         }
74 
75         /*for (int i = 0; i < 2; ++ i) {
76             for (int j = 0 ; j < 2; ++ j) {
77                 cout << Map[i][j] << " ";
78             }
79             cout << endl;
80         }*/
81         double ans = 100 * prim(Map, n);
82         if (ans > 0)
83             printf("%.1lf\n", ans);
84         else {
85             printf("oh!\n");
86         }
87         //cout << prim (Map, n) << endl;
88     }
89     return 0;
90 }