poj 3164 Command Network#有向最小树形图

有向最小树形图，贴个模板

#include <stdio.h>
#include <string.h>
#include <math.h>

#define V 128
#define E 10240
#define typec double // type of res
const typec inf = 0x3f3f3f3f; // max of res
typec res, dis[V];
int to[V], cp[V], tag[V];

struct Edge
{
    int u, v;
    typec c;
    Edge(int a = 0,int b = 0,double cc = 0.0)
    {
        u = a;
        v = b;
        c = cc;
    }
} eg[E];
int iroot(int i){
    if (cp[i] == i) return i;
    return cp[i] = iroot(cp[i]);
}
int dirtree(int root, int nv, int ne) // root: 树根
{ // vertex: 0 ~ n-1
    int i, j, k, circle = 0;
    memset(tag, -1, sizeof(tag));
    memset(to, -1, sizeof(to));
    for (i = 0; i < nv; ++i) dis[i] = inf;
    for (j = 0; j < ne; ++j) {
        i = iroot(eg[j].