UVa 11631 - Dark roads

　　题目大意：政府为了减小开支决定关闭一些路灯，同时保证照亮的路能连接所有路口。

　　又是一个MST问题，Kruskal算法，不过数据规模比较大，又Submission Error了...扔这吧...

 #include <cstdio>
 #include <vector>
 #include <algorithm>
 using namespace std;
 typedef pair<int, int> ii;
 #define MAXN 200100

 int p[MAXN];

 int find(int x)
 {
     return p[x] == x ? x : p[x]=find(p[x]);
 }

 int main()
 {
 #ifdef LOCAL
     freopen("in", "r", stdin);
 #endif
     int n, m;
     while (scanf("%d%d", &n, &m) && (n || m))
     {
         int u, v, w;
         int total_cost = ;
         vector<pair<int, ii> > EdgeList;
         for (int i = ; i < m; i++)
         {
             scanf("%d%d%d", &u, &v, &w);
             total_cost += w;
             EdgeList.push_back(make_pair(w, make_pair(u, v)));
         }
         sort(EdgeList.begin(), EdgeList.end());
         for (int i = ; i < n; i++)
             p[i]= i;
         int cost = ;
         for (int i = ; i < EdgeList.size(); i++)
         {
             w = EdgeList[i].first;
             u = EdgeList[i].second.first;
             v = EdgeList[i].second.second;
             int pu = find(u);
             int pv = find(v);
             if (pu != pv)
             {
                 cost += w;
                 p[pv] = pu;
             }
         }
         printf("%d\n", total_cost-cost);
     }
     return ;
 }