hdu 3367 Pseudoforest 最大生成树★

 #include <cstdio>
 #include <cstring>
 #include <vector>
 #include <algorithm>
 using namespace std;

 const int maxn = ;
 int n, m;
 struct node
 {
     int u, v, c;
 }g[maxn];
 long long ans;
 int fa[maxn];
 int ff[maxn];
 int ee[maxn];

 bool cmp(node a, node b){
     return a.c > b.c;
 }

 void init(){
     memset(ff, false, sizeof(ff));
     memset(ee, false, sizeof(ee));
     for (int i = ; i < n; i++){
         fa[i] = i;
     }
 }

 int find(int x){
     if (x == fa[x])
         return x;
     else
         return fa[x] = find(fa[x]);
 }

 void Union(int x, int y, int z){
     int a = find(x);
     int b = find(y);
     if (a == b){
         if (ff[a])
             return;
         ans += z;
         ff[a] = true;
     }
     else{
         if (ff[a] && ff[b])
             return;
         ans += z;
         fa[b] = a;
         if (ff[a] || ff[b])
             ff[a] = true;
     }
 }

 int main(){
     while (~scanf("%d%d", &n, &m)){
         if (n ==  && m == )
             break;
         init();
         int u, v, c;
         for (int i = ; i < m; i++){
             scanf("%d%d%d", &u, &v, &c);
             g[i].u = u;
             g[i].v = v;
             g[i].c = c;
         }
         //克鲁斯卡尔
         sort(g, g + m, cmp);    //按边从小到大排列
         ans = ;
         for (int i = ; i < m; i++){
             Union(g[i].u, g[i].v, g[i].c);
         }
         printf("%lld\n", ans);
     }
     //system("pause");
     return ;
 }