POJ 1287Networking

题意：多组数据输入的最小生成树果题

#include<algorithm>
#include<iostream>
#include<queue>
#include<map>
#include<vector>
#include<stack>
#include<set>
#include<cstring>
#include<cstdio>
using namespace std;
int first[505];
int vis[505];
typedef struct node{
	int x;
	int y;
	int date;
	friend bool operator< (node a,node b){
		return a.date<b.date;
	}
}node;
void csh(int m){
	for(int i=1;i<=m;i++){
		first[i]=i;
	}
	for(int i=1;i<=m;i++){
		vis[i]=1;
	} 
}
int find(int x){
	if(first[x]==x)  return x;
	else{
		return find(first[x]);
	}
}
void hb(int x,int y){
	x=find(x);
	y=find(y);
	if(x!=y){
		if(vis[x]>vis[y]){
			first[y]=x;
		}
		else{
			first[x]=y;
			if(vis[x]==vis[y]){
				vis[y]++;
			}
		}
	}  
}
node a[250010];
int main(){
	int m,n;
	while(cin>>m&&m!=0){
	cin>>n;
	csh(m);
	int d,b,c;
	for(int i=1;i<=n;i++){
			cin>>d>>b>>c;
			a[i].x=d;a[i].y=b;a[i].date=c;	
		}
	sort(a+1,a+n+1);
	int ans=0;
	int t=0;
	for(int i=1;i<=n;i++){
		if(find(a[i].x)==find(a[i].y)) continue;
		else{
			t++;ans+=a[i].date;
			hb(a[i].x,a[i].y);
			if(t==(n-1)){
				break;
			}
		}
	}
	cout<<ans<<endl;
}
	return 0;
}