图论——最小生成树

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<algorithm>
 4 
 5 using namespace std;
 6 
 7 int f[300000];
 8 
 9 struct point{
10     int x;
11     int y;
12     int z;
13 }edge[300000];
14 
15 bool cmp(point a,point b)
16 {
17     return a.z<b.z;
18 } 
19 
20 inline int Find(int a)
21 {
22     if(f[a]!=a) f[a]=Find(f[a]);
23     return f[a];
24 }
25 
26 inline void join(int a,int b)
27 {
28     int fa=Find(a);
29     int fb=Find(b);
30     if(fa!=fb) f[fa]=fb;
31 }
32 
33 int main(void)
34 {
35     
36     int n,m;
37     
38     scanf("%d%d",&n,&m);
39     
40     for(register int i=1;i<=m;i++)
41         scanf("%d%d%d",&edge[i].x,&edge[i].y,&edge[i].z);
42     
43      sort(edge+1,edge+1+m,cmp);
44     
45      for(register int i=1;i<=n;i++)
46         f[i]=i;
47     
48     int tot=0;
49     
50     int k=0;
51 
52     for(int i=1;i<=m;i++)
53     {
54     
55         if(Find(edge[i].x) != Find(edge[i].y))
56         {
57             join(edge[i].x,edge[i].y);
58             tot+=edge[i].z;
59             k++;
60         }
61         if(k==n-1) break;
62 
63     }
64     
65     printf("%d",tot);
66 }