hdu1879 继续畅通工程 基础最小生成树

 #include <cstdio>
 #include <cstdlib>
 #include <algorithm>
 #include <cmath>
 using namespace std;

 #define  MAXN 10005
 int fa[MAXN];
 struct node
 {
     int from, to, len;
 }arr[MAXN];

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

 int m;

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

 int main()
 {
     int n;
     while (scanf("%d",&n)&&n)
     {
         for (int i = ; i <= n; i++)
             fa[i] = i;
         m = ;
         int s = n*(n - ) / ;
         for (int i = ; i < s; i++)
         {
             int a, b, c, d;
             scanf("%d%d%d%d", &a, &b, &c, &d);
             if (d)
             {
                 int x = find(a);
                 int y = find(b);
                 if (x != y)
                     fa[y] = x;
             }
             else
             {
                 arr[m].from = a;
                 arr[m].to = b;
                 arr[m].len = c;
                 m++;
             }
         }

         sort(arr, arr + m, cmp);
         int ans = ;
         for (int i = ; i < m; i++)
         {
             int a = find(arr[i].from);
             int b = find(arr[i].to);
             if (a != b)
             {
                 ans += arr[i].len;
                 fa[b] = a;
             }
         }
         printf("%d\n", ans);
     }
     //system("pause");
     return ;
 }