hdu1301 Jungle Roads 基础最小生成树

 #include<iostream>
 #include<algorithm>
 using namespace std;

 const int maxn = ;
 int n, m;
 int fa[];
 struct node
 {
     int x, y;
     int cost;
 }arr[maxn];

 void init()
 {
     for (int i = ; i <= maxn; i++)
     {
         fa[i] = i;
     }
 }

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

 bool cmp(node a, node b)
 {
     return a.cost<b.cost;
 }

 int main()
 {
     char c1, c2;
     int k, c;
     while (cin >> n)
     {
         if (n == ) break;
         int j = ;    //表示边的数量
         init();
         for (int i = ; i<n; i++)
         {
             cin >> c1 >> k;
             while (k--)
             {
                 cin >> c2 >> c;
                 arr[j].x = c1 - 'A';
                 arr[j].y = c2 - 'A';
                 arr[j].cost = c;
                 j++;
             }
         }
         sort(arr, arr + j, cmp);    //排序
         int ans = ;
         for (int i = ; i<j; i++)
         {
             int fx, fy;
             fx = find(arr[i].x);
             fy = find(arr[i].y);
             if (fx != fy)
             {
                 ans += arr[i].cost;
                 fa[fy] = fx;
             }
         }
         cout << ans << endl;
     }
     return ;
 }