hdu 3371 最小生成树

 1 #include <stdio.h>
 2 #include <algorithm>
 3 using namespace std;
 4 
 5 const int N = 501;
 6 const int M = 25000;
 7 int f[N];
 8 int buffer[N];
 9 int n, m, k, e;
10 
11 void init()
12 {
13     e = 0;
14     for ( int i = 1; i <= n; i++ ) f[i] = i;
15 }
16 
17 int find_f( int x )
18 {
19     if ( f[x] != x ) f[x] = find_f(f[x]);
20     return f[x];    
21 }
22 
23 bool union_set( int x, int y )
24 {
25     x = find_f(x), y = find_f(y);
26     if ( x != y )
27     {
28         f[x] = y;
29         return true;
30     }
31     return false;
32 }
33 
34 struct Edge 
35 {
36     int u, v, w;
37 } edge[M];
38 
39 bool cmp( Edge a, Edge b )
40 {
41     return a.w < b.w;
42 }
43 
44 int main ()
45 {
46     int t;
47     scanf("%d", &t);
48     while ( t-- )
49     {
50         scanf("%d%d%d", &n, &m, &k);
51         init();
52         while ( m-- )
53         {
54             scanf("%d%d%d", &edge[e].u, &edge[e].v, &edge[e].w);
55             e++;
56         }
57         int cnt = 0;
58         while ( k-- )
59         {
60             int tmp;
61             scanf("%d", &tmp);            
62             for ( int i = 0; i < tmp; i++ )
63             {
64                 scanf("%d", buffer + i);
65             }
66             for ( int i = 0; i < tmp - 1; i++ )
67             {
68                 if ( union_set( buffer[i], buffer[i + 1] ) )
69                 {
70                     cnt++;
71                 }
72             }
73         }
74         if ( cnt == n - 1 )
75         {
76             printf("0\n");
77             continue;
78         }
79         int sum = 0;
80         sort( edge, edge + e, cmp );
81         for ( int i = 0; i < e; i++ )
82         {
83             if ( union_set( edge[i].u, edge[i].v ) )
84             {
85                 sum += edge[i].w;
86                 cnt++;
87                 if ( cnt == n - 1 ) break;
88             }
89         }
90         if ( cnt == n - 1 ) printf("%d\n", sum);
91         else printf("-1\n");        
92     }
93     return 0;
94 }