hdu 4424 Conquer a New Region (并查集)

///题意：给出一棵树，树的边上都有边权值，求从一点出发的权值和最大，权值为从一点出去路径上边权的最小值# include <stdio.h># include <algorithm># include <iostream># include <string.h>using namespace std;# define MAX 200010struct node{    int u,v;    int w;};struct node a[MAX];__int64 dis[MAX];///存以i为根结点的边权和int father[MAX],rank[MAX];///存以i为根结点的数的节点数void init()///初始化{    for(int i=0; i<=MAX; i++)    {        father[i]=i;        rank[i]=1;        dis[i]=0;    }}int cmp(node a1,node a2)///边权从大到小{    return a1.w>a2.w;}int find(int x){    if(x==father[x])        return x;    return father[x]=find(father[x]);}void Union(int x,int y,__int64 v){    father[x]=y;    rank[y]+=rank[x];    dis[y]=v;}int main(){    int i,n;    __int64 s1,s2;    while(~scanf("%d",&n))    {        for(i=1; i<n; i++)            scanf("%d%d%d",&a[i].v,&a[i].u,&a[i].w);        init();        sort(a+1,a+n,cmp);///        for(i=1; i<n; i++)        {            int fa=find(a[i].v);            int fb=find(a[i].u);            if(fa!=fb)///树中不会出现fa,fb相等的情况。。。。            {                s1=dis[fa]+a[i].w*rank[fb];///在fa集合中选点                s2=dis[fb]+a[i].w*rank[fa];///在fb集合中选点            }            if(s1>s2)                Union(fb,fa,s1);            else                Union(fa,fb,s2);        }        printf("%I64d\n",dis[find(1)]);    }    return 0;}