/*  Name: hdu1863畅通工程   Author: Try86  Date: 10/04/12 12:43  Description: 最小生成树(kruskal) */#include 
     
      #include 
      
       using namespace std;const int M = 5050;int p[M], sum; //sum统计顶点个数 struct edge {    int a;    int b;    int w;}e[M];int cmp(const void *a, const void *b) {    return (*(edge *)a).w - (*(edge *)b).w;} void init(int vs) {    for (int i=1; i<=vs; ++i) p[i] = i;    return ;}int find(int v) {    if (p[v] != v) p[v] = find(p[v]);    return p[v];}int join(edge e) {    int x, y;    x = find(e.a);    y = find(e.b);    if (x != y) {        ++sum;        p[x] = y;        return e.w;    }    return 0;}int kruskal(int es, int vs) {    int ans = 0;    init(vs);    qsort(e, es, sizeof(edge), cmp);    for (int i=0; i