[kuangbin带你飞]专题六 最小生成树 POJ 1287 Networking

最小生成树模板题

跑一次kruskal就可以了

 /* ***********************************************
 Author        :Sun Yuefeng
 Created Time  :2016/11/9 18:26:37
 File Name     :tree.cpp
 ************************************************ */

 #include<cstdio>
 #include<iostream>
 #include<algorithm>
 #include<cmath>
 #include<cstring>
 #include<string>
 #include<bitset>
 #include<map>
 #include<set>
 #include<stack>
 #include<vector>
 #include<queue>
 #include<list>
 #define M(a,b) memset(a,b,sizeof(a))
 using namespace std;
 typedef long long ll;
 const int inf=0x3f3f3f3f;
 const int maxn=;
 const int maxm=;
 const int mod=1e7+;
 int dx[]= {,,,-,,-,,-};
 int dy[]= {,-,,,-,,,-};

 int f[maxn],tol,n,m;

 struct _edge
 {
     int u,v,w;
 }edge[maxm];

 bool cmp(_edge a,_edge b)
 {
     return a.w<b.w;
 }

 void addedge(int u,int v,int w)
 {
     edge[tol].u=u;
     edge[tol].v=v;
     edge[tol].w=w;
     tol++;
 }

 int _find(int x)
 {
     if(f[x]==-) return x;
     else return f[x]=_find(f[x]);
 }

 int kruskal()
 {
     M(f,-);
     sort(edge,edge+tol,cmp);
     int cnt=,ans=;
     int u,v,w,f1,f2;
     for(int i=;i<tol;i++)
     {
         u=edge[i].u;
         v=edge[i].v;
         w=edge[i].w;
         f1=_find(u);
         f2=_find(v);
         if(f1!=f2)
         {
             ans+=w;
             f[f1]=f2;
             cnt++;
         }
         if(cnt==n-) break;
     }
     return ans;
 }

 int main()
 {
     //freopen("in.txt","r",stdin);
     //freopen("out.txt","w",stdout);
     while(~scanf("%d%d",&n,&m)&&n)
     {
         tol=;
         for(int i=;i<m;i++)
         {
             int u,v,w;
             scanf("%d%d%d",&u,&v,&w);
             addedge(u,v,w);
         }
         printf("%d\n",kruskal());
     }
     return ;
 }