【HDOJ】3367 Pseudoforest

并查集。

 #include <cstdio>
 #include <cstring>
 #include <cstdlib>

 #define MAXN 10005
 #define INF  0xffffff

 typedef struct {
     int c, s, e;
 } edge_st;

 edge_st edges[];
 int pre[MAXN];
 int deg[MAXN];
 int n, m, ans;

 int comp(const void *a, const void *b) {
     return ((edge_st *)b)->c - ((edge_st *)a)->c;
 }

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

 void merge(int i) {
     int a, b;

     a = find(edges[i].s);
     b = find(edges[i].e);
     if (a != b) {
         if (deg[a] == ) {
             pre[a] = b;
             ans += edges[i].c;
         } else if (deg[b] == ) {
             pre[b] = a;
             ans += edges[i].c;
         }
     } else {
         if (deg[a] == ) {
             ++deg[a];
             ans += edges[i].c;
         }
     }
 }

 int main() {
     int i;

     while (scanf("%d %d", &n, &m)!=EOF && (n||m)) {
         for (i=; i<m; ++i)
             scanf("%d %d %d", &edges[i].s, &edges[i].e, &edges[i].c);
         qsort(edges, m, sizeof(edge_st), comp);
         for (i=; i<n; ++i)
             pre[i] = i;
         memset(deg, , sizeof(deg));
         ans = ;
         for (i=; i<m; ++i)
             merge(i);
         printf("%d\n", ans);
     }

     return ;
 }