1 #include <cstdio>
 2 #include <algorithm>
 3 using namespace std;
 4 
 5 int N, M;
 6 struct Edge{
 7     int u, v, w;
 8     bool operator() (Edge a, Edge b)
 9     {
10         return a.w<b.w;
11     }
12 };
13 Edge e[5055];
14 int f[105];
15 
16 int getf(int x)
17 {
18     return x == f[x] ? f[x] : f[x] = getf(f[x]);
19 }
20 
21 bool merge(int a, int b)
22 {
23     int t1 = getf(a);
24     int t2 = getf(b);
25     if(t1 != t2){
26         f[t2] = t1;
27         return true;
28     }
29     return false;
30 }
31 
32 void kruskal()
33 {
34     for(int i = 1; i <= N; ++i)
35         f[i] = i;
36     sort(e+1, e+1+M, Edge());   //按边的权值从小到大排序
37     int ans = 0;
38     int cnt = 0;　　//记录生成树的边数
39     for(int i = 1; i <= M; ++i){
40         if(merge(e[i].u, e[i].v)){  //用并查集判断两个结点是否在同一个集合中
41             ans += e[i].w;
42             ++cnt;
43         }
44         if(cnt == N-1)  //直到选用了N-1条边后退出循环
45             break;
46     }
47     printf("%d\n", ans);
48 }
49 
50 int main()
51 {
52     while(scanf("%d", &N), N){
53         M = N*(N-1)/2;
54         for(int i = 1; i <= M; ++i){
55             scanf("%d%d%d", &e[i].u, &e[i].v, &e[i].w);
56         }
57         kruskal();
58     }
59     return 0;
60 }

 1 #include <cstdio>
 2 #include <cstring>
 3 
 4 const int INF = 0x3f3f3f3f;
 5 int N, M;
 6 int e[105][105];
 7 int dis[105];   //记录非树结点到生成树的最小距离
 8 bool vis[105];
 9 
10 void prim()
11 {
12     memset(vis, 0, sizeof(vis));
13     for(int i = 1; i <= N; ++i)
14         for(int j = 1; j <= N; ++j)
15             e[i][j] = (i == j ? 0 : INF);
16     int m = N*(N-1)/2;
17     int u, v, w;
18     for(int i = 1; i <= m; ++i){
19         scanf("%d%d%d", &u, &v, &w);
20         e[u][v] = e[v][u] = w;  //注意是无向图
21     }
22     for(int i = 1; i <= N; ++i)
23         dis[i] = e[1][i];
24     vis[1] = true;
25     int ans = 0;
26     int cnt = 1;    //记录生成树的结点数
27     while(cnt<N){
28         int min_dis = INF, u;
29         for(int i = 1; i <= N; ++i){
30             if(!vis[i] && dis[i]<min_dis){
31                 min_dis = dis[u = i];
32             }
33         }
34         vis[u] = true;
35         ++cnt;
36         ans += dis[u];
37         //更新非树结点到生成树的最小距离
38         for(int i = 1; i <= N; ++i){
39             if(!vis[i] && e[u][i]<dis[i]){
40                 dis[i] = e[u][i];
41             }
42         }
43     }
44     printf("%d\n", ans);
45 }
46 
47 int main()
48 {
49     while(scanf("%d", &N), N){
50         prim();
51     }
52     return 0;
53 }