图论-最小生成树-Kruskal算法

 1 #include<cstdio>
 2 #include<algorithm>
 3 using namespace std;
 4 #define MAXN 
 5 #define MAXM 
 6 int father[MAXN],n,m,cnt,ans,a,b;
 7 struct node
 8 {
 9     int u,v,val;
10 }edge[MAXM];
11 int cmp(node a,node b)
12 {
13     return a.val<b.val;
14 }
15 int find(int x)//并查集+路径压缩
16 {
17     if(father[x]==x)return x;
18     else return father[x]=find(father[x]); 
19 }
20 int main()
21 {
22     scanf("%d",&n);
23     for(int i=1;i<=n;i++)
24         father[i]=i;
25     for(int i=1;i<=n;i++)
26     {
27         for(int j=1;j<=n;j++)
28         {
29             scanf("%d",&a);
30             if(a==0)continue;
31              edge[++cnt].u=i;
32              edge[cnt].v=j;
33             edge[cnt].val=a;
34         }
35     }
36     sort(edge+1,edge+cnt+1,cmp);
37     m=cnt;
38     cnt=1;
39     for(int i=1;i<=m;i++)
40     {
41         a=find(edge[i].u);
42         b=find(edge[i].v);
43         if(a==b)continue;
44         else//连边
45         {
46             father[b]=a;
47             cnt++;
48             ans+=edge[i].val;
49             if(cnt==n)break;
50         }
51     }
52     printf("%d",ans);//最小生成树权值和
53     return 0;
54 }