B - Networking POJ - 1287

 1 #include <iostream>
 2 #include <vector>
 3 #include <map>
 4 #include <string>
 5 #include <queue>
 6 #include <stack>
 7 #include <algorithm>
 8 #include <set>
 9 
10 #include <cstdio>
11 #include <cstring>
12 #include <cmath>
13 #include <cstdlib>
14 using namespace std;
15 
16 const int INF=0x3f3f3f3f;
17 const int SIZE=100;  ///不是很懂要开多大 就开的大一点了
18 
19 int id[SIZE];
20 int sz[SIZE];
21 int m,n;
22 
23 struct node{
24     int start;
25     int end;
26     int val;
27 
28 }edge[10000];   ///emmmm
29 void  clear()
30 {
31     for(int i=0;i<=n;i++)
32     {
33         id[i]=i;sz[i]=1;
34     }
35 }
36 int find(int x)
37 {
38     if(x!=id[x])  id[x]=find(id[x]);
39     return id[x];
40 }
41 
42 void un(int p,int q)
43 {
44     p=find(p);
45     q=find(q);
46     if(p==q) return ;
47     if(sz[p]<sz[q])
48         id[p]=find(q);
49     else
50     {
51         if(sz[p]==sz[q])
52             sz[p]++;
53         id[q]=find(p);
54     }
55 }
56 
57 int kruskal()
58 {
59     int sum=0;
60     for(int i=0;i<m;i++)
61     {
62         if(find(edge[i].start)!=find(edge[i].end))
63         {
64             un(edge[i].start,edge[i].end);
65             sum+=edge[i].val;
66         }
67     }
68     return sum;
69 
70 }
71 
72 bool cmp(node a,node b)
73 {
74     return a.val<b.val;
75 }
76 int main()
77 {
78     while(cin>>n)
79     {
80         if(n==0) break;
81         cin>>m;
82         clear();
83         int a,b,value;
84         for(int i=0;i<m;i++)
85         {
86             cin>>a>>b>>value;
87             edge[i].start=a;
88             edge[i].end=b;
89             edge[i].val=value;
90         }
91         sort(edge,edge+m,cmp);
92         cout<<kruskal()<<endl;
93     }
94     return 0;
95 }

 1 #include <iostream>
 2 #include <vector>
 3 #include <map>
 4 #include <string>
 5 #include <queue>
 6 #include <stack>
 7 #include <set>
 8 
 9 #include <cstdio>
10 #include <cstring>
11 #include <cmath>
12 #include <cstdlib>
13 using namespace std;
14 
15 const int INF=0x3f3f3f3f;
16 const int SIZE=100;
17 
18 int dis[SIZE];
19 int graph[SIZE][SIZE];
20 int n,m;
21 int vis[SIZE];
22 
23 int prim()
24 {
25     memset(vis,0,sizeof(vis));
26     int index;
27     int sum=0;
28     for(int i=1;i<=n;i++)  ///起点是1
29         dis[i]=graph[i][1];
30     vis[1]=1;
31     for(int i=2;i<=n;i++)
32     {
33         int minn=INF;
34         for(int j=1;j<=n;j++)
35             if(!vis[j]&&dis[j]<minn)
36         {
37             minn=dis[j];index=j;
38         }
39         vis[index]=1;
40         sum+=minn;
41         for(int j=1;j<=n;j++)
42             if(dis[j]>graph[j][index]&&!vis[j])
43                 dis[j]=graph[j][index];
44     }
45     return sum;
46 }
47 int main()
48 {
49      while(cin>>n)
50     {
51         if(n==0) break;
52         cin>>m;
53         memset(graph,INF,sizeof(graph));
54         int a,b,value;
55         for(int i=0;i<m;i++)
56         {
57             cin>>a>>b>>value;
58             if(graph[a][b]>value)   ///注意重复就好
59                 graph[a][b]=graph[b][a]=value;
60         }
61         cout<<prim()<<endl;
62     }
63     return 0;
64 }