Kruskal HDOJ 1233 还是畅通工程

题目传送门

 /*
     最小生成树之kruskal算法--并查集（数据结构）实现
     建立一个结构体，记录两点和它们的距离，依照距离升序排序
     不连通就累加距离，即为最小生成树的长度
 */
 #include <cstdio>
 #include <algorithm>
 #include <cstring>
 #include <cmath>
 using namespace std;

 const int MAXN = 5e3 + ;
 const int INF = 0x3f3f3f3f;
 int rt[MAXN];
 struct Node
 {
     int u, v, w;
 }node[MAXN];

 bool cmp(Node x, Node y) {return x.w < y.w;}

 int Find(int x)    {return (rt[x] == -) ? x : rt[x] = Find (rt[x]);}

 void Union(int x, int y)
 {
     x = Find (x);    y = Find (y);
     if (x > y)    rt[y] = x;
     else if (x < y)    rt[x] = y;
 }

 bool same(int x, int y)    {return (Find (x) == Find (y));}

 int main(void)        //HDOJ 1233 还是畅通工程
 {
     //freopen ("inB.txt", "r", stdin);
     int n, m;

     while (~scanf ("%d", &n) && n)
     {
         m = n * (n - ) / ;
         memset (rt, -, sizeof (rt));
         for (int i=; i<=m; ++i)
         {
             scanf ("%d%d%d", &node[i].u, &node[i].v, &node[i].w);
         }
         sort (node+, node++m, cmp);
         int sum = ;
         for (int i=; i<=m; ++i)
         {
             int x = node[i].u;    int y = node[i].v;
             int w = node[i].w;
             if (!same (x, y))    {Union (x, y);    sum += w;}
         }
         printf ("%d\n", sum);
     }
 }