> #include<stdio.h>
> #include<stdlib.h>
> #define MAX 1000
> int matrix[MAX+1][MAX+1];
> int visited[MAX+1];
> int hasspf;
> int vexnum;
> int firstadjvex(int u)
> {
> 	int j;
> 	for(j=1;j<=MAX;j++)
> 		if(matrix[u][j])
> 			return j;
> 	return -1;
> }
> int nextadjvex(int u,int w)
> {
> 	int j;
> 	for(j=w+1;j<=MAX;j++)
> 		if(matrix[u][j])
> 			return j;
> 	return -1;
> }
> void DFS(int v)
> {
> 	int w;
> 	visited[v]=1;
> 	for(w=firstadjvex(v);w>=0;w=nextadjvex(v,w))
> 		if(!visited[w])
> 			DFS(w);
> }
> int findunvisited(int j)
> {
> 	int i;
> 	for(i=1;i<=vexnum;i++)
> 		if(!visited[i]&&i!=j)
> 			return i;
> 	return -1;
> }
> int is_spf(int j)
> {
> 	int temp[MAX+1];
> 	int i,num,w,v;
> 	for(v=1;v<=vexnum;v++)
> 		visited[v]=0;
> 	for(i=1;i<=vexnum;i++)
> 	{
> 		temp[i]=matrix[j][i];
> 		matrix[j][i]=0;
> 	}
> 	num=0;
> 	while((w=findunvisited(j))!=-1)
> 	{
> 		num++;
> 		DFS(w);
> 	}
> 	for(i=1;i<=vexnum;i++)
> 		matrix[j][i]=temp[i];
> 	return num;
> }
> 
> int init()
> {
> 	int from,to;
> 	int i,j;
> 	for(i=1;i<MAX;i++)
> 		for(j=1;j<MAX;j++)
> 			matrix[i][j]=0;
> 	vexnum=0;
> 	scanf("%d",&from);
> 	if(from==0)
> 		return 0;
> 	while(from)
> 	{
> 		if(from>vexnum)
> 			vexnum=from;
> 		scanf("%d",&to);
> 		if(to>vexnum)
> 			vexnum=to;
> 		matrix[from][to]=1;
> 		matrix[to][from]=1;
> 		scanf("%d",&from);
> 	}
> 	return 1;
> }
> main()
> {
> 	int i,j;
> 	int nsnet;
> 	j=i=0;
> 	while(init())
> 	{
> 		i++;
> 		printf("Network #%d\n",i);
> 		hasspf=0;
> 		for(j=1;j<=vexnum;j++)
> 		{
> 			nsnet=is_spf(j);
> 			if(nsnet>1)
> 			{
> 				printf("  SPF node %d leaves %d subnets\n",j,nsnet);
> 				hasspf=1;
> 			}
> 		}
> 		if(!hasspf)
> 			printf("  No SPF nodes\n");
> 	}
> }
> 
>