（模板）prim最小生成树

#include<cstdio>
#include<cstring>
using namespace std;
const int N=1000;
const int INF=0x7fffffff;
int g[N][N],n,m,minEdge[N],mini[N],ans=0;
void (){
	for(int i=1;i<=n;i++)
		{minEdge[i]=g[1][i];mini[i]=1;}
	minEdge[1]=0;
	int min,x;
	for(int i=1;i<n;i++){
		min=INF;
		for(int j=1;j<=n;j++)  
			if(minEdge[j]!=0&&minEdge[j]<min)
				min=minEdge[j],x=j,cout<<mini[j]<<' '<<j<<endl;
		ans+=min;              //找到的边加入的mst
		minEdge[x]=0;          //以后不再处理此点
		for(int j=1;j<=n;j++)  //更新最短边
			if(minEdge[j]!=0&&minEdge[j]>g[x][j])
			{minEdge[j]=g[x][j];mini[j]=x;}
				
	}
	cout<<ans<<endl;
}
int main(){
	//freopen("test.in","r",stdin);
	memset(g,0x7f,sizeof(g));
	cin>>n>>m;
	int x,y,w;
	for(int i=1;i<=m;i++){
		cin>>x>>y>>w;
		g[x][y]=g[y][x]=w;
	}
	prim();
	return 0;
}